New attribute "deltax" to correct for horizontal distance differences in eye baseline between camera and human vision. by isenberg · Pull Request #54 · steren/stereo-img

isenberg · 2025-04-06T01:56:45Z

The name deltax is currently more a testing attribute as later it would be better to use an attribute baseline in mm and disparityAdjustment in % which in combination then results in the technical deltax number. PR is for #53

…d the right image from rightsrc * added support for any angle value

documented new type "pair" and optional any degree value for attribute "angle"

layout and typo fixed

* added error handling for type pair when src-right is missing * renamed rightsrc to src-right

…ype=pair

…rection in percent of image width to match the convergence point between right and left image. Positive means the right image needs to be moved right to match the left image.

gemini-code-assist

Hello @isenberg, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

Summary of Changes

This pull request introduces a new deltax attribute to the stereo-img component, which allows for horizontal correction of the convergence point between the left and right images in a stereo pair. This is intended to address differences in eye baseline between the camera and human vision. The deltax attribute represents the horizontal correction as a percentage of the image width. The PR also modifies the stereo-parser.js file to apply this correction when parsing stereo pair images, and updates the README to document the new attribute.

Highlights

New deltax attribute: Introduces a deltax attribute to the stereo-img component for horizontal correction of stereo pair images.
Horizontal correction implementation: Modifies stereo-parser.js to apply the deltax correction during stereo pair image parsing.
Documentation update: Updates the README to document the new deltax attribute and its usage.

Changelog

Click here to see the changelog

README.md
- Added documentation for the new deltax attribute, explaining its purpose and usage.
parsers/stereo-parser/stereo-parser.js
- Calculates the horizontal shift dx based on the deltax option.
- Adjusts the angle option based on the absolute value of dx.
- Modifies the getImageData calls for both left and right eyes to account for the horizontal shift, ensuring the correct portions of the images are extracted.
- Ensured that the file ends with a newline character.
stereo-img.js
- Added a deltax getter to retrieve the value of the deltax attribute.
- Added a baseline setter that maps to the deltax attribute, allowing setting deltax via baseline.
- Modified the parseStereoPair call to include the deltax value as an option, defaulting to 0 if not provided.

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A stereo pair's askew,
Deltax's here to see it through.
A shift to the left,
A right eye bereft,
Brings vision into view.

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Code Review

The pull request introduces a new attribute deltax to correct for horizontal distance differences in eye baseline between camera and human vision. The changes seem reasonable, but there are a few areas that could be improved for clarity and maintainability.

Summary of Findings

Clarity of deltax usage: The purpose and effect of deltax could be made clearer in the code and documentation. Consider adding comments to explain the calculations and adjustments made using deltax.
Naming consistency: The attribute is named deltax but the setter uses baseline. This inconsistency could be confusing. Consider renaming the setter to deltax for consistency.
Angle adjustment: The angle adjustment based on deltax might not be intuitive. Adding a comment explaining the reasoning behind this adjustment would improve readability.

Merge Readiness

The pull request introduces a useful feature, but there are some areas that could be improved for clarity and consistency. Addressing the naming inconsistency and adding comments to explain the calculations would make the code more maintainable. I am unable to approve this pull request, and recommend that others review and approve this code before merging. I recommend addressing the comments before merging.

gemini-code-assist · 2025-04-06T01:57:03Z

+    set baseline(val) {
+      if (val) {
+        this.setAttribute('deltax', val);
+      } else {
+        this.removeAttribute('deltax');
+      }


The setter is named baseline while the getter is named deltax. This is inconsistent and could be confusing. It would be better to name both deltax for consistency. Also, consider adding a comment explaining that this is horizontal correction in percent of image width.

Suggested change

set baseline(val) {

if (val) {

this.setAttribute('deltax', val);

} else {

this.removeAttribute('deltax');

}

set deltax(val) {

if (val) {

this.setAttribute('deltax', val);

} else {

this.removeAttribute('deltax');

}

}

It seems indeed there is a copy paste error

gemini-code-assist · 2025-04-06T01:57:03Z

+* `deltax`: (Optional) Horizontal correction in percent of image width to match the convergence point between right and left image for type `pair`.
+  - `PERCENT`: Any number between -100 and 100. 0 means no correction. Positive means the left image needs to be moved left and the right image needs to be moved right to match the convergence point in both images.


Consider rephrasing to clarify the effect of positive and negative values. For example: "Positive values shift the left image left and the right image right to simulate a closer convergence point."

gemini-code-assist · 2025-04-06T01:57:03Z

-      leftEye =  ctx.getImageData(0, 0, width, height);
-      rightEye = secondaryCtx.getImageData(0, 0, secondaryWidth, secondaryHeight);
+      const dx = Math.round(width * (options.deltax ?? 0) / 100 / 2);
+      options.angle = options.angle * (100-Math.abs(dx))/100;


It would be helpful to add a comment explaining why the angle is being adjusted based on dx. What is the reasoning behind options.angle = options.angle * (100-Math.abs(dx))/100;?

I agree with this suggestion, please explain formula

gemini-code-assist · 2025-04-06T01:57:03Z

+      const dx = Math.round(width * (options.deltax ?? 0) / 100 / 2);
+      options.angle = options.angle * (100-Math.abs(dx))/100;
+      leftEye =  ctx.getImageData(Math.max(0, dx), 0, width-Math.abs(dx), height);
+      rightEye = secondaryCtx.getImageData(Math.max(0, -dx), 0, secondaryWidth-Math.abs(dx), secondaryHeight);


Consider adding comments to explain the purpose of dx and the Math.max(0, dx) calculation. For example:

// dx: horizontal shift in pixels const dx = Math.round(width * (options.deltax ?? 0) / 100 / 2); // Ensure the starting index is not negative leftEye = ctx.getImageData(Math.max(0, dx), 0, width-Math.abs(dx), height); rightEye = secondaryCtx.getImageData(Math.max(0, -dx), 0, secondaryWidth-Math.abs(dx), secondaryHeight);

I agree with this suggestion, please explain formula

steren

This repo doesn't have unit tests but relies on the developers testing via example images

We need test images to showcase this new feature. Can you find images that need deltax, add them to the examples folder and add this in the index.html dropdown list?

steren · 2025-04-06T20:01:21Z

+      const dx = Math.round(width * (options.deltax ?? 0) / 100 / 2);
+      options.angle = options.angle * (100-Math.abs(dx))/100;
+      leftEye =  ctx.getImageData(Math.max(0, dx), 0, width-Math.abs(dx), height);
+      rightEye = secondaryCtx.getImageData(Math.max(0, -dx), 0, secondaryWidth-Math.abs(dx), secondaryHeight);


I agree with this suggestion, please explain formula

steren · 2025-04-06T20:01:24Z

-      leftEye =  ctx.getImageData(0, 0, width, height);
-      rightEye = secondaryCtx.getImageData(0, 0, secondaryWidth, secondaryHeight);
+      const dx = Math.round(width * (options.deltax ?? 0) / 100 / 2);
+      options.angle = options.angle * (100-Math.abs(dx))/100;


I agree with this suggestion, please explain formula

steren · 2025-04-06T20:01:44Z

+    set baseline(val) {
+      if (val) {
+        this.setAttribute('deltax', val);
+      } else {
+        this.removeAttribute('deltax');
+      }


It seems indeed there is a copy paste error

isenberg · 2025-04-08T02:53:15Z

I added comments to explain the formula now and fixed the wrong accessor function name.

isenberg · 2025-04-08T03:08:21Z

BTW, for testing I currently use the Google Cardboard view on the Android phone with Chrome. The WebXR simulation extension for Edge I used before fails now, I guess a bug in the extension.

isenberg and others added 8 commits March 25, 2025 18:18

* added stereo-img type "pair" which loads the left image from src an…

856311f

…d the right image from rightsrc * added support for any angle value

Update README.md

d03472b

documented new type "pair" and optional any degree value for attribute "angle"

Update README.md

be28fc3

layout and typo fixed

* type attribute is optional when src-right is set

a2fea5c

* added error handling for type pair when src-right is missing * renamed rightsrc to src-right

left/right pair extracted from Panasonic-DMC-GX8.jpg for tests with t…

a2ff195

…ype=pair

new optional attribute 'deltax' for image type 'pair': Horizontal cor…

9ccd571

…rection in percent of image width to match the convergence point between right and left image. Positive means the right image needs to be moved right to match the left image.

Merge remote-tracking branch 'upstream/main'

50911ab

moved documentation to README

437f5ba

gemini-code-assist Bot reviewed Apr 6, 2025

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gemini-code-assist Bot suggested changes Apr 6, 2025

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isenberg mentioned this pull request Apr 6, 2025

Disparity adjustment for cameras with larger eye distance than human vision #53

Open

steren requested changes Apr 6, 2025

View reviewed changes

isenberg added 3 commits April 7, 2025 19:26

Merge branch 'steren:main' into main

1a0bfb6

fixed wrong accessor function name

95179ec

added comment

ff82ba4

		* `deltax`: (Optional) Horizontal correction in percent of image width to match the convergence point between right and left image for type `pair`.
		- `PERCENT`: Any number between -100 and 100. 0 means no correction. Positive means the left image needs to be moved left and the right image needs to be moved right to match the convergence point in both images.

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isenberg commented Apr 6, 2025 •

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