Post-de-squeeze crop-to-guide Fit/Fill monitoring

[erik-sutton95]

Goal

Add a post-de-squeeze crop-to-guide viewing mode so an anamorphic image can fill more of the phone or tablet display using the selected aspect-ratio guide, instead of always showing the entire very-wide de-squeezed frame.

Feedback

With a 2× anamorphic de-squeeze, the full image becomes extremely wide on a phone. The resulting Fit view can be quite small, while much of the displayed width may consist of vignetted or otherwise unusable lens edges. Cropping the monitor view to the intended delivery guide would make the usable composition much larger and easier to judge.

Proposed experience

• Keep the current Fit view, which shows the complete post-de-squeeze camera image.
• Add Guide Fill, which crops in post-de-squeeze image coordinates to the selected framing guide—such as 2.39:1, 2.35:1, 2:1, 16:9, or a custom guide—and scales that crop to use the available monitor viewport.
• Use a familiar media-viewer interaction:
  • Pinch with two fingers to zoom between the useful views.
  • Snap cleanly to Fit and Guide Fill rather than requiring pixel-perfect gesture control.
  • Allow a double-tap or an explicit Fit/Fill control to switch states quickly.
  • Briefly show the active state and selected guide, for example Fit — Full 2× de-squeeze or Fill — 2.39:1.
• If the selected guide has been repositioned using movable crop marks, Guide Fill should use that same crop position.
• In a deliberate framing/edit mode, allow the filled crop to be repositioned within valid image bounds and provide a one-tap reset to center.
• Remember the choice for the monitoring session and reconnect, with an obvious route back to the full image.

Interaction safeguards

• Keep one-finger touch autofocus and other camera-control gestures unchanged; zoom should require a two-finger pinch.
• Do not let a casual pinch leave the image at an ambiguous near-Fit or near-Fill scale—snap when it enters a sensible threshold.
• Clearly indicate whenever any part of the source frame is hidden.
• Ensure record state, critical warnings, scopes, and camera controls remain visible and are not cropped with the image.
• Support portrait and landscape device orientation, iPhone, iPad, and Android without inventing separate framing geometry on each platform.

Rendering and geometry

Apply transforms in a deterministic order:

1. Decode and orient the Nikon live-view frame.
2. Apply the selected anamorphic de-squeeze ratio.
3. Resolve the selected aspect-ratio guide and its position in the de-squeezed coordinate space.
4. Crop and scale that guide region into the monitor viewport for Guide Fill.
5. Align focus peaking, zebras, false color, grids, crop boundaries, autofocus points, and other overlays to the final displayed geometry.

This should be a GPU/display transform only. It must not change the Nikon camera recording, alter downloaded originals, or imply that the selected crop has been baked into the file.

Scopes and monitoring tools

• Keep analysis overlays spatially aligned after de-squeeze, crop, zoom, pan, rotation, and orientation changes.
• Define whether scopes analyze the full source frame or the visible Guide Fill crop, expose that choice where useful, and label it truthfully.
• Keep safe areas and composition guides meaningful in both states; in Guide Fill, the active guide should become the viewport boundary rather than being drawn redundantly as an inset rectangle.
• Avoid scaling cached overlay bitmaps independently from the live frame, which could make peaking, zebras, or autofocus indicators drift.

Success looks like

An operator monitoring a 2× anamorphic Nikon Z image selects a 2.39:1 guide and switches from Fit to Guide Fill. The vignetted outer edges disappear, the intended composition becomes substantially larger on the device, all monitoring overlays remain correctly aligned, and the camera continues recording the untouched full source frame.

Open questions

• Should Guide Fill be available for any framing guide or only guides narrower than the post-de-squeeze image?
• Should the app default to the last state per device, per lens/de-squeeze preset, or per project/session?
• What snap thresholds feel intentional without fighting normal pinch gestures?
• Should scopes default to the full source or visible crop, and can both be offered without clutter?
• How should Guide Fill interact with external displays, clean feed, multi-device mirroring, and playback de-squeeze?
• Should an optional temporary edge reveal let the operator quickly inspect what is outside the filled crop?

Related OpenZCine work

• Movable crop marks — positions the intended crop within the full image.
• Playback de-squeeze — ensures anamorphic geometry is also available during playback.