Stereozoom Documentation

Version 1.0 • © 2026 by Trevor Alyn

Display Device Requirements

Stereozoom lets you view stereoscopic (3D) images on a stereo-capable display such as a 3D TV (via HDMI) or a pair of XREAL ONE glasses. You MUST have such a display device to use this app.

In order to work with this app, the display device must be capable of displaying half-width side-by-side stereo. See your display device's documentation to verify that it supports this mode.

NOTE: Some display devices may have built-in alignment adjustment. For example, some Sony 3D TVs have a 3D Depth Adjustment setting. I recommend that you turn off the device-based alignment adjustment (or, in the case of Sony's 3D Depth Adjustment, set it to zero). Stereozoom can handle the alignment on its own.

Stereoscopic Image Requirements

To be viewable in Stereozoom, JPEG and PNG files must be full-width side-by-side pairs with the left view on the left and the right view on the right, like an old stereoscope card. For example:

You can create such stereo pairs yourself with a 3D camera, or you can find them on the Internet. If you shoot left and right frames separately, you can combine them into stereo pairs with the fantastic free tool StereoPhoto Maker, which also includes batch automatic alignment tools.

Stereozoom also supports HEIC files that use Apple's spatial photos format.

Stereoscopic Video Requirements

To be viewable in Stereozoom, stereoscopic videos must be in half-width side-by-side format. Apple's spatial videos are also supported, but can be displayed only in 2D on macOS Sequoia.

Selecting the Root 3D Folder

The Root 3D Folder is the folder that contains all of your side-by-side stereo image files. These image files can be in subfolders of this folder, but the app will not be able to see anything that is outside of this folder.

IMPORTANT: When you first launch the app, you must select the folder that contains ALL of your stereoscopic images. Choose carefully! You can change it later, but if you do so, you run the risk of breaking links in the database and losing any adjustments and tagging.

Using a Game Controller

Stereozoom is designed to be used with a macOS-compatible game controller. This is so that you can enjoy the stereo view without having a GUI in the way; you don't have to look away from the screen to use a game controller. To run the app with a game controller, simply pair the game controller with your Mac via Bluetooth, and then launch Stereozoom.

If you do not have a game controller, I recommend the Terios Wireless Controller (compatible with PS4).

If you have not used a game controller before, the app includes a Help screen for every mode, indicating what each control on the game controller does. To show the Game Controller Help, press the Options or Menu button on the game controller. Press it again to hide the Game Controller Help.

Using the Control Screen

If your stereo display is connected to your Mac as a second monitor (over HDMI, for example), the Control Screen lets someone drive Stereozoom with the mouse from the Mac's own screen while the audience watches the stereo display. Choose Window > Show Control Screen (Command+K) to open it. Drag the main Stereozoom window onto the stereo display and make it full screen with its green button; macOS remembers where each window goes.

The Control Screen shows a live preview of the stereo display, either as the Left Eye alone or as a red/cyan Anaglyph of both eyes, and below it the controls for whatever the stereo display is showing right now. The controls change as you move between the File Browser View, the Menu, and the various app modes.

Every button shows its corresponding keyboard key. The Common Controls panel on the left contains controls that are common to most modes.

Buttons marked HOLD REPEATS repeat if you hold the mouse button down, the same way the game controller's buttons do.

Drag inside the Pan circle to pan the image around.

Drag the Alignment wheel left or right to change the horizontal alignment (if Manual Horizontal Alignment is turned on). Drag the Zoom wheel up or down to zoom in and out.

The Help and Edit Tags buttons at the top of the Control Screen let you view this Help file and edit the image tags you can apply to images. These functionalities are also available from the menu bar.

The Control Screen reopens at launch if it was open when you quit.

NOTE: If you close the main stereo window by mistake, choose Window > Show Stereo Window to bring it back.

Basic Functionality

For basic stereo (3D) image viewing:

1. Plug your Mac into your stereo display device (for example, your 3D TV).
2. Launch Stereozoom. If this is the first time you've launched it, a dialog box instructs you to select your Root 3D Folder. Choose this folder carefully -- you can change it later, but you risk breaking the links in the app database. (You can add files to this folder or remove them from this folder at any time without causing problems.)
3. Click the green button at upper left to go full-screen.
4. Put your 3D display or other stereo display device into side-by-side half-width stereo mode.
5. Park the mouse cursor somewhere at the bottom of the screen to keep it from interfering with the images.
6. Display the File Browser View by pressing the B button on the game controller or the F key on the keyboard. Here, you can navigate up and down with the game controller's DPad Up and DPad Down buttons (or with the Up and Down arrow keys).
   
   
7. You can navigate to the parent folder by pressing the DPad Left button on the game controller or the Left Arrow key. Note that you cannot navigate outside of the Root 3D Folder you selected when you first launched the app.
8. To view a side-by-side image file in 3D, select it and then press A on the game controller or Enter on the keyboard. See the following table for information on how to pan and zoom and use the other features of this view.
9. To navigate to the next file, press the Right Shoulder button (keyboard P). To navigate to the previous file, press the Left Shoulder button (keyboard O).

When you are viewing a stereo image, the following controls are available.

File Browser View

The File Browser View lets you navigate the file system inside your Root 3D Folder.

Keeping Your Place: When you quit or exit a folder, the app remembers the last file you viewed in that folder. If you return to the folder later, it will take you to that file.

Cell Background Color: Rows in the File Browser View that represent folders have a colored background that indicates how many image files in that folder have been viewed recently. The more image files there are in a folder that you haven't viewed in a long time (or have never viewed), the darker the background color. Folders with all-unviewed images have a black background. Similarly, rows for image files indicate how recently those files have been viewed by the brightness of their background color (brighter = viewed more recently). Note that this feature applies only to image files; the database does not keep track of video files.

Thumbnails: Thumbnail images for stereo image files show what the image looked like when the thumbnail was originally created. So, for example, if you apply an Image Filter or an HSB adjustment to an image and then go back to the File Browser View, the thumbnail will not show the updated image. To update the thumbnail, go to the Menu and choose Utilities > Clear Thumbnails for This Folder or Clear All Thumbnails. The next time you view the File Browser View, the thumbnails will be updated.

Folders with Many Files: The first time you open a folder with a large number of files, the loading indicator may display for quite a while. This is normal. After that, entering the folder will be much faster.

Caching: The app proactively loads the next and previous images to speed up navigation.

File Browser View Control Reference

Alignment

Proper alignment is critical to being able to enjoy a stereo image. Consequently, Stereozoom has a number of features for helping you to view misaligned images.

Horizontal Alignment

Horizontal alignment refers to how the left and right images overlap each other. In a perfectly aligned image, everything is sharp and you can see all the depth. However, in a poorly aligned image, it's hard to resolve the depth, and eye strain can occur. Horizontal alignment is especially important when you zoom in on a stereoscopic image, because different parts of the same image may require different horizontal alignment values.

There are three menu items related to horizontal alignment, all on the Alignment submenu:

• Menu > Alignment > Automatic Horizontal Alignment (toggle): Lets you turn Automatic Horizontal Alignment on and off.
• Menu > Alignment > Manual Horizontal Alignment (toggle): Lets you turn Manual Alignment on and off.
• Menu > Alignment > Automatic Horizontal Alignment Method: Lets you choose the method used by Automatic Horizontal Alignment.

The first two controls work in combination as follows:

• If Automatic Horizontal Alignment and Manual Horizontal Alignment are both off: You cannot adjust the alignment of images at all.
• If Automatic Horizontal Alignment is on and Manual Horizontal Alignment is off: Images align themselves automatically. Automatic Horizontal Alignment works continuously as you pan and zoom around in an image, and may result in a "skipping" or "jumping" sensation as the alignment is updated.
• If Automatic Horizontal Alignment is off and Manual Horizontal Alignment is on: You can align images manually with the X axis of the Right Thumbstick or the dial in the Control Screen.
• If Automatic Horizontal Alignment and Manual Horizontal Alignment are both on: You can manually adjust the horizontal alignment after the automatic alignment is done. Pan and zoom to the part of the image you want to look at, and after you release the thumbsticks, you can use the Right Thumbstick or the dial in the Control Screen to apply additional alignment adjustment.

When manually adjusting depth with the right thumbstick, remember that moving the thumbstick to the right brings the entire scene toward you, and moving it to the left pushes the entire scene away from you.

Automatic Horizontal Alignment Method

There are two options for Automatic Horizontal Alignment:

• Method 1 (the default): The fastest mode, and probably the best mode for general use.
• Method 2: May be a bit better in some situations, but can get slow if there is a lot of dust or other noise in the image.

NOTE: I'm aware that Automatic Horizontal Alignment doesn't always work the way you expect. It's a complicated problem. I plan to keep working on it.

"Stuck" Horizontal Alignment

When you are zoomed in on an image, Automatic Horizontal Alignment can occasionally get "stuck" in a mode where all you see is a narrow, misaligned image. If this happens, just press DPad Down (keyboard Z) and the horizontal alignment will be reset. If the problem persists, consider turning Automatic Horizontal Alignment off for this image.

Vertical Alignment

Vertical alignment may be necessary for images that were shot (for example) with two different cameras, scans of stereo slides with misaligned chips, or via cha-cha. Images shot with a 3D camera usually do not need to be vertically aligned.

To turn this feature on or off, navigate to Menu > Alignment > Automatic Vertical Alignment.

NOTE: The Vertical Alignment feature is not perfect, especially for images that also have rotational alignment issues.

NOTE: Ideally, try to use Automatic Vertical Alignment only with images that have visible vertical alignment problems. For images that are already mostly vertically aligned, the setting may cause misalignment.

NOTE: Vertical alignment corrections are baked into an image file if you have the app save or resave the current image. For example, if you use the Bake In Adjustments feature, any applied vertical alignment corrections are baked in along with any Image Filters or HSB Adjustments.

Rotational Alignment

Rotational alignment may be necessary for images that were shot (for example) with two different cameras, scans of stereo slides with misaligned chips, or via cha-cha. Images shot with a 3D camera usually do not need to be rotationally aligned.

To turn this feature on or off, navigate to Menu > Alignment > Automatic Rotational Alignment.

NOTE: The Automatic Rotational Alignment feature is currently problematic. It may improve in future versions, but for now, try to use Automatic Rotational Alignment only with images that have visible rotational alignment problems. For images that are already mostly rotationally aligned, the setting may cause misalignment.

NOTE: Rotational alignment corrections are baked into an image file only by Full Realign and Realign All Images in This Folder (in the Image Operations submenu), and when you save a stereo pair in Traveling Stereo Mode or Bracketed Depth Mode. In each case the rotation is measured again on the full-resolution images, and only if Automatic Rotational Alignment is on. Bake In Adjustments and the Crop commands do not apply a rotational correction.

Monoscopic vs. Stereoscopic Files

Most files in a stereo collection are likely stereoscopic: a left-eye view and a right-eye view in one file. However, some may be monoscopic (for example, if you are using Bracketed Depth Mode).

Because monoscopic and stereoscopic files can be mixed together in the same folder, Stereozoom must try to figure out which kind each file is automatically. However, there currently is no foolproof way to do this, so Stereozoom allows you to override this decision for individual files.

How The Mono/Stereo Determination is Made

Stereozoom checks the following, in order, and stops at the first one that gives an answer:

1. Stereo metadata. An image that is marked in its own metadata as a stereo pair (for example, a spatial HEIC photo) is always treated as stereoscopic.
2. Aspect Ratio. An image at least twice as wide as it is tall is treated as stereoscopic. This settles the large majority of side-by-side files without examining the picture itself.
3. Content. For narrower images, Stereozoom compares the left and right halves of the picture. If they look like two views of the same scene, the image is treated as stereoscopic; otherwise it is treated as monoscopic. If the comparison can't reach a decision either way, the image is treated as stereoscopic.

Videos are checked the same way, using their first frame. (Videos have no stereo metadata, so the first step never applies to them.)

The folder vote. When you enter a folder for the first time, Stereozoom checks the first five files, and sets a monoscopic or stereoscopic flag on the folder according to the majority (in other words, it assumes that the rest of the files in the folder are the same type as most of those five). In a folder with fewer than five files, every file is checked, and a tie results in the folder's flag being stereoscopic. Until the flag is set, each file is displayed according to its own check. A folder's mono/stereo flag is saved between launches.

A file that is flagged as monoscopic is always displayed with zero horizontal alignment, because the two eyes are showing the identical image. Operations that need two separate halves (such as Swap Sides, both Crop commands and Full Realign) are greyed out in the Image Operations Submenu, and Depth Grading Mode is not available.

Changing the Flag for a Single File

If a file is displayed the wrong way, open the Main Menu (X button or keyboard M) while it is displayed and choose Toggle Image/Video Mode. The menu item shows the file's current flag (Monoscopic or Stereoscopic), and each time you choose it, the file switches to the other one. The item appears only for image and video files, and only while you are browsing normally (not in one of the special modes).

NOTE: This change is temporary. It's not saved, and it's lost as soon as the file is reloaded (for example, once you have navigated far enough away from it, or after an image operation). It also doesn't change the folder's vote. To fix a whole folder permanently, refresh the folder's flag instead, as described below.

Refreshing the Flag for a Folder

If a whole folder is being displayed the wrong way (for example, because you replaced its monoscopic photos with stereoscopic pairs, or because the first few files you viewed were not typical of the rest), open the Main Menu and choose Utilities > Clear Mono/Stereo Flag for This Folder. Stereozoom discards the folder's mono/stereo flag, deletes the folder's cached thumbnails, and checks the displayed files again. A new vote then begins, and the folder's flag is settled again once five more files have been checked.

Only the current folder is affected. Each subfolder has its own flag.

Image Tagging

To display the Tagging Menu for an image, press the A button (keyboard T) while an image is displayed. (Only image files can be tagged.)

To navigate to a tag, use the DPad Up and DPad Down buttons or the keyboard Up and Down Arrow keys. To apply a tag, highlight it and press A (keyboard Enter); press A again to remove it. Applied tags display in yellow.

The Tagging Menu can have up to three sections, from top to bottom: SESSION TAGS (see Session Tags), FREQUENTLY USED TAGS (see Most Frequently Used Tags) and ALL TAGS, which lists every tag. The first two appear only when they are turned on and have something in them.

You can use this menu to assign as many tags as you like to the image. Assigned image tags display in the bottom of the Info View (Y button or keyboard I) and the File Browser View (B button or keyboard F).

Tag Hierarchy

Tags can be organized into a hierarchy: any tag can have a parent tag, and a parent can have any number of child tags, which can have children of their own. For example, you might put "Beach", "Mountains" and "Desert" under a parent tag called "Landscapes". You set a tag's parent in the Edit Image Tags view.

In the ALL TAGS section of the Tagging Menu, only the top-level tags are shown at first. A tag that has children is marked with ▸:

• To show a tag's children, highlight it and press DPad Right (keyboard Right Arrow or E). The marker changes to ▾, and the children appear indented beneath it.
• To hide them again, press DPad Left (keyboard Left Arrow). If a child is highlighted, its parent's branch closes and the parent is highlighted.
• Only one branch is open at a time: opening a tag closes any other open branch, except the tags above the one you opened.
• If a closed parent tag has a child (or a child of a child) applied to the current image, the parent's name is shown in amber, as a hint to open it.

Each tag in the hierarchy is a tag in its own right. Applying a child tag does not apply its parent, and applying a parent does not apply its children. The Session Tags and Frequently Used Tags sections, and the tag list used for browsing by tag, are flat lists that show no hierarchy. When you browse by tag, selecting a parent tag matches only images that have that tag itself, not its children.

Two tags in different branches can have the same name; they are still separate tags.

Editing Image Tags

The app comes with a default set of image tags, but you can delete them and create your own. To edit the list of tags, click Edit Tags at the top of the Control Screen, or choose Tags > Edit Tags… from the Mac's menu bar. The Edit Image Tags view opens on the Control Screen. It is a flat, mouse-and-keyboard view rather than a stereo one, so it stays off the stereo display, which keeps showing the picture.

• To add a tag, click Add, then enter the tag name and click Add Tag.
• To edit an existing tag, select it in the list on the left, make your changes to the Tag Name field on the right, and then click Save Tag Name Changes.
• To delete a tag, select it in the list on the left and then click Delete. The tag will be removed from all records that use it, and will no longer display in the image tag list. If the tag has children, they are not deleted; they move up one level, to the deleted tag's parent (or to the top level).
• To move a tag in the tag hierarchy, select it in the list on the left and click Set Parent…. In the list that appears, select the new parent tag, or None (Top Level) to make it a top-level tag, and then click Set Parent. The tag's own children move with it. A tag cannot be put under itself or under one of its own children.
• To replace all occurrences of a tag with a different tag, select the tag you want to replace in the list on the left, then click Replace to display a list where you can select the replacement tag. Select the replacement tag and then click Replace. The tag will be replaced in all records that use it.

The list on the left shows the hierarchy, with child tags indented beneath their parents.

When you are done making changes, click Exit.

Browsing by Image Tag

Once you have tagged a number of images, you can go back and view only images that have particular tags applied to them. To use this feature, navigate to Menu > Browse By... to display the Browse By submenu.

1. Browse File System: Lets you view files by navigating through the file system with the File Browser View.
2. Browse by Tags AND: Lets you select one or more tags, and then displays all images that have ALL of those tags applied to them.
3. Browse by Tags OR: Lets you select one or more tags, and then displays all images that have ANY of those tags applied to them.
4. Never Viewed in This Folder: Displays all images and videos in the current folder and its subfolders that you have never viewed.
5. Untagged in This Folder: Displays all images and videos in the current folder and its subfolders that have no tags.

In browse-by-tag mode, you can navigate through the list of matching images with the File Browser View. You can also navigate through the matching images with the Left Shoulder button (keyboard O) and Right Shoulder button (keyboard P).

To exit browse-by-tag mode, navigate to Menu > Browse By... Browse File System.

Most Frequently Used Tags

If the Frequently Used Tags feature is on, up to 20 of your most-used tags display near the top of the tagging menu, in a section titled FREQUENTLY USED TAGS with a dark blue background, ordered top-to-bottom from most-used to least-used. The full list of tags displays below this section.

To turn this feature on or off, navigate to Menu > Preferences > Advanced > Show Frequently Used Tags.

Session Tags

If the Session Tags feature is on, tags that you have applied during this session display at the very top of the tagging menu, in a section titled SESSION TAGS with a dark green background, ordered top-to-bottom from least-used to most-used in this session. This can speed up tagging if you have a large set of related images. Session tags are cleared when you quit the app.

NOTE: If the list of Session Tags gets too long, you can choose Menu > Clear Session Tags.

To turn this feature on or off, navigate to Menu > Preferences > Advanced > Show Session Tags.

Image Filters

If you navigate to Menu > Image Operations > Image Filter..., the app displays a list of Image Filters that you can apply to the active image.

NOTE: Image Filters and HSB adjustments do not alter the original image. Instead, they are saved in the database and applied to the image again the next time you display it. If you want to bake in Image Filters and HSB Adjustments, choose Menu > Image Operations > Bake In Adjustments.

HSB Adjustment Mode

If you navigate to Menu > Image Operations > Adjust HSB, controls display at the top of the screen that allow you to adjust the image's hue, saturation, brightness, and gamma.

Use the DPad Up and Down buttons (keyboard up and down arrow) to navigate between the options:

• Hue: Use the right thumbstick's horizontal axis (or the right and left arrow keys) to change the value. 0.5 is normal hue.
• Saturation: Use the right thumbstick's horizontal axis (or the right and left arrow keys) to change the value. 0.5 is normal saturation.
• Brightness: Use the right thumbstick's horizontal axis (or the right and left arrow keys) to change the value. 0.5 is normal brightness.
• Gamma: Use the right thumbstick's horizontal axis (or the right and left arrow keys) to change the value. 0.5 is normal gamma.
• Inverted: When this is selected, you can press A (keyboard X) to invert or uninvert the image.
• Reset All: When this is selected, you can press A (keyboard X) to reset all adjustments to their defaults.

When you're happy with the way the image looks, press B (keyboard Enter).

NOTE: Image Filters and HSB adjustments do not alter the original image. Instead, they are saved in the database and applied to the image again the next time you display it. If you want to bake in Image Filters and HSB Adjustments, choose Menu > Image Operations > Bake In Adjustments.

HSB Adjustment Mode Control Reference

Cropping

Stereozoom lets you crop images to the following aspect ratios:

• Normal (entire screen)
• Square (1:1)
• Realist (1:1.05)
• 4:3
• 3:2

If you want to select an aspect ratio before cropping, navigate to Menu > Aspect Ratio... and choose the desired option. Then, zoom and pan the view until it shows what you want the cropped image to look like. Next, choose Menu > Image Operations > Crop and Save as New File or Menu > Image Operations > Crop and Save Over Original.

NOTE: Any applied alignment adjustments are baked into an image file when you crop it.

IMPORTANT: Any applied Image Filters and HSB adjustments are NOT baked into to the cropped file. If you want to bake them into the cropped file, select it after the crop and choose Menu > Image Operations > Bake In Adjustments.

Session Commands

If the Session Commands feature is on, menu commands that you have recently chosen in certain menus display at the very top of their menus with a dark green background. This can speed things up if you are using a given command repeatedly. Session commands are cleared when you quit the app.

To turn this feature on or off, navigate to Menu > Preferences > Advanced > Show Session Commands.

Auxiliary Images

I originally built this app to view scans of cardboard-mounted stereoscopic slides from the 1950s. Sometimes these slides have writing on them, so I scan the slide mount as well as the image. This feature lets you view such a mount scan in the app.

To use this feature:

1. Make sure each mount scan (or whatever auxiliary image you want) has the same name as its corresponding stereo image file.
2. Create a folder named "!AuxiliaryImages" in the folder containing the image scans.
3. Put the auxiliary images into the "!AuxiliaryImages" folder.
4. While viewing an image, press the Left Trigger button on the game controller or press keyboard A. The view updates to show the auxiliary image. In this mode, you can pan and zoom in for a closer look,
5. To return to the main image, press the Left Trigger button or keyboard A.

Note that if you have multiple folders with auxiliary images, you will need an "!AuxiliaryImages" folder in each of them.

Stereo Video Playback Mode

Stereo Video Playback Mode lets you view side-by-side half-width stereo video in 3D. You can pause, fast-forward, reverse, move forward or backward in slow motion, zoom, pan, and make stereo pairs from the current view.

To enter Stereo Video Playback Mode, navigate to a video file in the File Browser view and press the A button (keyboard Enter) to display the video file. Then open the Main Menu (X button or keyboard M) and choose Enter Stereo Video Playback Mode. The video begins playing immediately.

Spatial video in .mov format is supported.

Picking up where you left off: The app remembers where you stopped watching each video and resumes from that point the next time you play it. If you watch a video all the way to the end (or stop within the first few seconds), the saved position is cleared and the video starts from the beginning next time.

Progress bar: A thin bar along the bottom of each view shows your current position in the video.

Scanning

The fast-forward and fast-reverse options go up to 120x, which is fast enough to move through an hour-long video in about half a minute. Not every Mac can decode and draw video that quickly, so above a certain speed (depending on your Mac and on the video file), Stereozoom stops trying to draw frames at all and scans instead.

While the video is scanning, the last drawable frame stays on the screen, but the progress bar along the bottom keeps updating. A message at upper right says "Scanning [speed]".

To exit scanning, press the A button or the spacebar.

NOTE: Stereozoom works out which speeds your Mac can draw by measuring them the first time it tries to play a video. To clear this setting, navigate to Menu ▸ Utilities ▸ Reset Video Speed Limit; the app discards the current value and measures again the next time you play a video.

Stereo Video Playback Mode Control Reference

Zoom Sequences

A Zoom Sequence is a saved sequence of framings (zoom, pan offset, and horizontal alignment) for one or more stereo images. When you play a Zoom Sequence back, the app smoothly animates from one framing to the next. You can play a Zoom Sequence in the app, and you can render a Zoom Sequence as side-by-side or spatial (MV-HEVC) stereo video. After you create a Zoom Sequence, you can edit the timing of each step, and even combine several Sequences into one.

Zoom Sequences are saved as JSON files in a folder named "Zoom Sequences" at the root of your Root 3D Folder. Each Zoom Sequence file appears in the File Browser View alongside your other files.

NOTE: Any Image Filter or HSB adjustment saved for an image is applied during playback and rendering of a Zoom Sequence.

Creating a Zoom Sequence

To create a Zoom Sequence:

1. Display a stereo image.
2. Navigate to Menu > Zoom Sequences... > Create Zoom Sequence. (This command is available only when an image is displayed.)
3. Pan, zoom, and align the image to the first framing you want, then navigate to Menu > Zoom Sequences... > Save Step (keyboard S) to capture it as a step. A message confirms the number of steps you have captured.
4. Move to the next framing and capture another step. If you make a mistake, navigate to Menu > Zoom Sequences... > Undo Last Step (keyboard U) to remove the most recently captured step.
5. Once you have captured at least two steps, navigate to Menu > Zoom Sequences... > Save Zoom Sequence (keyboard F). The Zoom Sequence is saved into the "Zoom Sequences" folder, named after the image. If a Zoom Sequence with that name already exists, you are asked to confirm overwriting it.

To abandon a capture in progress, navigate to Menu > Zoom Sequences... > Cancel Zoom Sequence and confirm.

NOTE: While you are capturing a Zoom Sequence, do not go to a different image file, because the Zoom Sequence's steps belong to the image you started with. Pan, zoom, alignment, the Info View (Y) and the Left Thumbstick button (Automatic Horizontal Alignment on/off) work as usual during capture, but several controls change:

• X (keyboard M) opens the Zoom Sequences menu directly instead of the top level of the menu, so the items below are one press away (B closes the menu).
• B (keyboard B) does nothing rather than opening the File Browser View, and A (keyboard T or Enter) does nothing rather than opening the tagging menu.
• The Left and Right Shoulder buttons (keyboard O and P) do nothing, so you cannot move to another image by accident.
• The Left Trigger (keyboard A) does nothing rather than showing the Auxiliary Image, and the Right Thumbstick button (keyboard L) does nothing rather than showing one side only.

Playing and Rendering a Zoom Sequence

When you display a saved Zoom Sequence file from the File Browser View, press the A button (keyboard T or Enter) to play it back immediately, or navigate to one of these commands:

• Play Zoom Sequence: Plays the Sequence back on screen (same as pressing the A button/T/Enter directly). The app navigates to each image in turn and animates through its steps. Automatic Horizontal Alignment is turned off for the duration so the Sequence's captured alignment values play back exactly as saved.
• Render Zoom Sequence to Video: Renders the entire Sequence to video, saved next to the Sequence file. Menu > Preferences > Advanced > Zoom Sequence Video Format chooses what is written: Side by Side (the default) writes two side-by-side stereo .movs, a full-width and a half-width one; Spatial (MV-HEVC) writes a single spatial .mov that Photos, QuickTime Player, Apple Vision Pro and iPhone 15 Pro and later show in 3D; Both writes all three. The animation is displayed on screen while the video renders. Note that spatial encoding requires hardware support.
• Edit Zoom Sequence: Enters Zoom Sequence Editing Mode.

While a Zoom Sequence renders, a progress bar displays along the bottom. A loading indicator displays if a new image needs to load, and while the video file is being finalized at the end.

During playback or rendering, all input is suspended except the B button (keyboard Escape), which cancels and returns the image to its normal view. A cancelled render discards its partial video files.

Editing Zoom Sequence Timing

Each step in a Zoom Sequence has three timing values, in seconds:

• Delay Before: How long to hold the previous framing before the transition into this step begins.
• Duration: How long the eased transition into this step's framing takes.
• Delay After: How long to hold this step's framing after the transition completes.

NOTE: On the first step of a Zoom Sequence, only the Delay Before value applies.

To edit these values, display a saved Zoom Sequence, then navigate to Menu > Zoom Sequences... > Edit Zoom Sequence. A stereoscopic editor overlays the Sequence, previewing the current step's framing on the image. Use DPad Left and DPad Right (left and right arrow keys) to move between the timing fields, and DPad Up and DPad Down (up and down arrow keys) to change the selected value by one second at a time. Delay Before and Delay After can go as low as zero seconds; Duration cannot go below one second.

To preview your changes without leaving the editor:

• Press the Left Shoulder button (keyboard G) to play the step before, the current step, and the step after, then return to editing. Press again during the preview to stop it early.
• Press the Left Trigger button (keyboard P) to play the entire Zoom Sequence in place, then return to editing. Press it again during the preview to stop it.

When you are done, press the B button (keyboard Escape). You are asked whether to save your changes: press A to save, or B to discard them. Either way, you return to normal viewing.

Combining Zoom Sequences

You can join several existing Zoom Sequences into a single, longer Zoom Sequence that plays through all of their images in order. To do this, navigate to Menu > Zoom Sequences... > Combine Zoom Sequences... (available when at least two Zoom Sequence files are present). A list of all your saved Zoom Sequences displays.

Select two or more Zoom Sequences in the order you want them to play; each one you select is highlighted. Then select Save Combined Zoom Sequence at the bottom of the same list (it shows how many Sequences you have selected). The combined Zoom Sequence is saved in the "Zoom Sequences" folder, named after the first image, plus a count of the additional images (for example, "Beach + 2 more").

Traveling Stereo Mode

Traveling Stereo Mode lets you create side-by-side full-width stereo pairs from video files where the camera is traveling sideways. This is useful, for example, if you have drone video that is traveling horizontally.

The controls are similar to those for Bracketed Depth Mode. There are three important ideas to understand:

• Starting Location: The location of the first frame in the pair. By varying the starting location, you can play with different framings.
• Range: The set of frames being displayed. For example, the range may be from frame 3 to frame 7, meaning that frame 3 is on the left and frame 7 is on the right.
• Gap: The distance between the two frames. For example, if you're combining frame 3 and 5, the gap between them is 2. The larger the gap, the more depth the pair has.

You can see both the numbers of the first and last frames in the range and the gap between them at the top of the screen:

To enter Traveling Stereo Mode, navigate to the video file in the File Browser View and press the A button (keyboard Enter) to display it. Then navigate to Menu > Enter Traveling Stereo Mode.

NOTE: Spatial (MV-HEVC) video cannot be reencoded; the app says so and enters the mode on the original.

Once you are in Traveling Stereo Mode:

• Use the right trigger button (keyboard R) to skip ahead 30 frames at a time until you find a section where the image appears to have depth. You can skip backward by 30 frames with the left trigger button (keyboard Q).
• To zero in on the frame range you want, use the right shoulder button (keyboard E) to skip ahead by one frame, or the left shoulder button (keyboard W) to skip back by one frame.
• To increase the depth of the image, increase the size of the frame range by pressing DPad Right (keyboard F).
• To decrease the depth of the image, decrease the size of the frame range by pressing DPad Left (keyboard D).
• Depending on the direction of travel, the depth may appear inverted. To fix this, press the Right Thumbstick button (keyboard X).
• When the pair looks right, press the A button (keyboard Return) and confirm to save it as a full-width stereo pair next to the video file.

The frame-stepping buttons repeat if you hold them down, so you can travel through a long video quickly. A thin progress bar along the bottom shows where you are in the video.

If Automatic Horizontal Alignment is on, the app re-aligns the pair as you change frames, and again as you pan and zoom. If you hold down a button to make it fast-repeat, Automatic Horizontal Alignment is suspended until you release it.

NOTE: Panning and zooming affect only what you see on screen; a saved stereo pair is always the full, uncropped frame at full resolution.

Reencoding Video

When you enter Traveling Stereo Mode, you have the option of reencoding the video first. Reencoding the video makes it faster to access specific frames and can speed things up if you are using a large gap. However, it can take a long time, and it should usually be unnecessary. If you want to reencode the video before you enter the mode, press X (keyboard X) when the confirmation dialog displays. The reencoded video is automatically deleted when you exit Traveling Stereo Mode.

Traveling Stereo Mode Control Reference

Bracketed Depth Mode

Bracketed Depth Mode lets you build stereo pairs from a set of monoscopic photos of a single subject shot with something like a macro rail. In this mode, you can pair such images interactively in stereo, and adjust the depth of the scene on the fly.

The controls are similar to those for Traveling Stereo Mode. There are three important ideas to understand:

• Starting Location: The location of the first image in the pair. By varying the starting location, you can play with different framings.
• Range: The set of images that includes the first and last image. For example, the range may be from image 3 to image 7, meaning that image 3 is on the left and image 7 is on the right.
• Gap: The distance between the two images. For example, if you're combining images 3 and 5 in a folder, the gap is 2. The larger the gap, the more depth the pair has.

The Left and Right Shoulder buttons adjust the starting location of the displayed pair. The DPad Left and DPad Right buttons decrease and increase the range (and therefore, the depth). The status line at the top of the screen shows the current range and identifies the currently displayed files.

If the camera was traveling left to right, the depth should look correct by default. If the camera was traveling right to left, press the Right Thumbstick button (keyboard X) to swap the views and correct the depth. The status line shows SWAPPED while the views are exchanged. The app remembers whether a folder's views were swapped, and the next time you enter Bracketed Depth Mode in that folder, the views start out swapped again.

The Right Thumbstick button (keyboard X) works the same way it does in Traveling Stereo Mode: it cycles through four steps. Press once to swap the views. Press again to see the left side only, and a third time to see the right side only, so you can compare the two images without removing your 3D glasses. The fourth press returns to normal (unswapped) stereo. The status line shows SWAPPED, LEFT ONLY or RIGHT ONLY, as appropriate. If the folder was swapped when you last left it, the mode opens swapped, and the next press goes straight to left only.

To enter Bracketed Depth Mode, display the image you want the first pair to start from (usually the first image in the folder), then navigate to Menu > Enter Bracketed Depth Mode and confirm. The selected image is shown on the left, and the next image on the right. (If you select the last image in the folder, it is shown on the right and the image before it on the left. If the folder's views start out swapped, as described above, left and right are exchanged.) The menu item is available only if the folder contains at least two images, and it is hidden in a folder whose mono/stereo flag is stereoscopic.

Automatic Horizontal Alignment may fail if the range you are using is too large (in other words, if not enough of the two images overlaps), or if there are vertical alignment issues. In such situations, Automatic Horizontal Alignment is suspended. You can try pressing DPad Down to see if the image can be aligned (see "Stuck" Horizontal Alignment).

Saving Bracketed Stereo Pairs

To save the currently displayed pair, press the A button (keyboard Return). Saved pairs are put into a subfolder named "!SBS" in the folder you are working in.

NOTE: If you save as a Spatial Photo, the app writes real camera data into the file rather than generic defaults: the lens focal length comes from the source photo’s EXIF, and the stereo baseline is worked out from Preferences > Bracketed Depth Rail Step multiplied by the number of frames between the two views. Set the rail step to the distance you actually moved the camera between shots, or the depth in the resulting spatial photo will be wrong. This setting has no effect on JPEG or PNG output.

NOTE: Panning and zooming affect only what you see on screen. A saved pair is always the full frame at full resolution.

Finishing With a Folder

When you have saved every pair you want from a folder of monoscopic files, press the B button (Escape key) to exit Bracketed Depth Mode. At this point you have two choices: simply leave the mode and return to normal image viewing (A button / key), or leave the mode and clean up the folder (X button / key). Either way, you are returned to the image view (or to the File Browser View, if no image is left to display). If you press X (Exit and Move Mono Files to !StereozoomTrash), the app does the following:

1. It moves the monoscopic images into a folder of the same name inside the "!StereozoomTrash" folder.
2. It moves the final pairs from the "!SBS" folder to the folder that contained the monoscopic files.
3. It puts the empty "!SBS" folder into your Mac's Trash

This leaves you with a folder of stereo pairs.

Bracketed Depth Mode Control Reference

Convert to Stereo Mode

Convert to Stereo Mode lets you convert a monoscopic image to a stereoscopic image. You can adjust the depth of the photo interactively before you save it.

IMPORTANT: The quality of any stereo conversion depends on the method being used for that conversion. The method currently used by the app is OK, but don't expect professional results. If you want a high-quality stereo conversion, I suggest you look elsewhere.

To enter Convert to Stereo Mode, display the image you want to convert, navigate to Menu > Enter Convert to Stereo Mode. The app takes a moment to analyze the image, and then the converted pair appears. The depth value displays at the top, and you can adjust it with the DPad Left (D key) and DPad Right (F key). The image updates each time you change the depth value.

DPad Left and Right set the Depth: right for more, left for less, with the value shown at the top of the screen. Depth is the greatest distance anything in the picture moves between the two eyes, measured as a percentage of the image width, so the preview and the file you save look the same however large the original is. Zero means no depth at all — both eyes see the same flat picture, which is a useful thing to flick back to when you are judging how much is too much.

To save the image as a stereo pair, press the A button (keyboard Return). The app saves the converted pair as a full-width side-by-side file at full resolution, in the format set by Preferences > Save Format. The image is saved in the same folder as the original, with -Converted added to the name. Converting the same image again adds a number rather than overwriting, so you can save stereo pairs with different depth values and compare them later.

NOTE: If you save as a Spatial Photo, the file gets generic camera values rather than real ones. Unlike Bracketed Depth Mode, where the rail step is a real distance the camera moved, there is no actual camera separation here to record — the depth was invented from the picture.

NOTE: Panning and zooming affect only what you see on screen. A saved conversion is always the full frame at full resolution, cropped only by the alignment you have set.

Convert to Stereo Mode Control Reference

Depth Grading Mode

Depth Grading Mode lets you adjust how the depth of a side-by-side stereo photograph sits relative to the screen when it is displayed.

To enter it, display the stereo image you want to grade, then navigate to Menu > Enter Depth Grading Mode. The app measures the depth of the image and displays it in the Depth Budget panel, which shows how much depth the pair will have with the changes you have made.

There are five parameters you can adjust:

• Convergence is where the stereo window (the plane of the screen) sits in the scene. You can adjust this with the Right Thumbstick's X axis (keyboard [ and ]). Moving it one way brings the whole scene toward you; moving it the other way sends the scene back behind the screen. This does not change how much depth the pair has; only where that depth sits.
• Floating windows are thin black strips down the left edge of the left eye and the right edge of the right eye. Something that is in front of the screen but cut off by the edge of the frame looks wrong, because the frame edge appears to be behind it. The strips bring the edge of the frame forward so it is in front of that object again. You can widen or narrow them with the Right and Left Shoulder buttons (keyboard R and E).
• Depth Amount is how much depth the pair has, from 0% (flat) through 100% (as photographed), up to 130%. You can change it with the DPad Left and Right buttons (keyboard - and =). The depth is squeezed toward (or stretched away from) the stereo window, so whatever is at the plane of the screen stays there while everything in front of it and behind it moves. The image for each eye is warped using a depth map that the app builds on the fly when you enter the mode, so it may take a moment for changes to apply. Note that very fine edges can show small artifacts at low amounts, and above 100% the app has to fill in slivers of background that neither camera saw.
• Depth Curve lets you change how the depth is shared out between the near and far parts of the scene, without changing the total depth. Push the Right Thumbstick up (or press the Right Trigger, keyboard W) to give the foreground more roundness at the expense of the background; pull it down (Left Trigger, keyboard Q) for the reverse. The thumbstick moves this value smoothly, and the triggers and keys move the value in steps.
• Depth EQ works like a graphic equalizer for depth. Press the Y button (keyboard H) to focus the histogram in the Depth Budget panel. There, each bar is a band of depth, nearest on the left, and the white tick over each bar is that band's depth gain. Use the DPad Left and Right buttons (left and right arrow keys) to pick a band, then use DPad Up and Down (up and down arrow keys) to give that range of depth more or less room. The total stays the same, so raising one band gives the rest slightly less. Press B or Y (Escape or H) to leave the histogram. However hard the curve and EQ are pushed, nothing can end up behind something it was in front of.

Fit to Comfort (X button, keyboard F) sets the convergence, the Depth Amount and the floating windows for you, and leaves the curve and EQ as you set them. It puts the nearest part of the scene on the screen plane, unless that would push the farthest part too far behind it; if the pair still has more depth than is comfortable, it lowers the Depth Amount until it does not; and then it sizes each floating window to cover whatever is in front of the screen at that edge.

When the adjusted depth looks right, press the A button (keyboard Return) to save an adjusted version of the image. The saved file has "-Graded" appended to its name.

NOTE: The Right Thumbstick's up and down movement is the Depth Curve in this mode, so to zoom with the game controller, hold down the Left Thumbstick button while moving the Right Thumbstick up or down. (Sorry, I ran out of gamepad controls.) The , and . keys zoom as usual.

NOTE: The quality of this feature is dependent on the quality of the depth map created by the app, and currently the app's depth maps are not perfect.

Depth Grading Mode Control Reference

Menu Reference

To open the Main Menu, press the X button (keyboard M). Within any menu:

• Use the DPad Up and DPad Down buttons (or the up and down arrow keys) to navigate up and down.
• Use the A button (keyboard Enter) to select an item or enter a submenu.
• If you are in a submenu, use DPad Left (left arrow key) to navigate up one level.
• Press button B (keyboard Escape) to close the menu.
• The commands available in the Menu vary by file type and mode.

The menu is only reachable while browsing normally, and inside Traveling Stereo Mode and Bracketed Depth Mode. It is not reachable in HSB Adjustment Mode, Auxiliary Image display, Stereo Video Playback Mode, Convert to Stereo Mode, Depth Grading Mode, or while editing or playing back a Zoom Sequence.

Main Menu

Items whose name ends in "..." open a submenu. Items marked "(toggle)" change state with each press and show their current value as a suffix, for example "Automatic Horizontal Alignment: Enabled". Delete File and Undo Delete File always sit at the top of the menu, below any Session Commands.

Image Operations Submenu

Swap Sides, Flip Horizontally, and Rotate 180° (Image Operations submenu) overwrite the original image file, so each one shows you the result first and asks you to confirm it. You can zoom and pan around the preview to verify that it looks correct before you save it.

Image Filter Submenu

Selecting an Image Filter applies it to the current image. Image Filters and HSB adjustments are mutually exclusive — choosing an Image Filter clears any saved HSB values for the current image, and vice-versa.

Fit & Align Submenu

Aspect Ratio Submenu

This submenu controls how the app crops the display area. This is mainly intended for when you are preparing to crop an image.

Browse Submenu

Preferences Submenu

Alignment Submenu

Everything that decides how the left and right images are registered against each other. Every item is a setting that stays in force until you change it. (Full Realign and Realign All Images in This Folder, which rewrite image files, are in the Image Operations submenu.)

Note that the Fit & Align submenu is a different thing despite the name: its Align Left/Right/Top/Bottom items move the view around inside the window and have nothing to do with stereo alignment.

Advanced Preferences Submenu

Font Size Submenu

Note: Changes to the Font Size setting do not take effect until you close the menu.

Pan Speed and Zoom Speed Submenus

Pan Speed and Zoom Speed are separate settings with the same four choices.

Save Format Submenu

JPEG Quality Submenu

Utilities Submenu