[Webkit-unassigned] [Bug 288115] createImagebitmap distorted grayscale PNG

[bugzilla-daemon at webkit.org]

https://bugs.webkit.org/show_bug.cgi?id=288115

--- Comment #6 from sunjm10 at gmail.com ---
Hi Alexey, I have attached my minimum HTML file for reproducing this issue and the test PNG file. Also attached the screenshots for the steps to reproduce. 

1. Loading the provided html in Safari 18.3. Make sure "GPU process: Canvas Rendering" feature flag is open. 
2. Click "Choose File" to upload the PNG file provided in "PNG file for testing ". This is a gray color space PNG file, 8bits per channel.
3. After uploading, the image is rendered on a canvas. It looks like the attachment Step1-Rendering PNG on a canvas. 
4. Click "Enhance to make noise viewable" button. What will happen is: It loops over the pixel data obtained on this canvas, if see any values such as 254 or 1, then changing it to 100. The purpose of this step is to make any potential permutations viewable, e.g., [1,0,0,255] will become [100,0,0,255]. [254,255,255,255] will become [100,255,255,255]. 
5. On safari, the noises are enhanced and now viewable. See the attachment Step 2-Enhancing the potential noises to make them viewable.
Note1: On chrome or firefly, repeat the reproduction steps. The enhanced noises are not reproducible. 
Note2: On Safari 18.3, if turning "GPU Process: Canvas Rendering" OFF, restart, and repeat the above steps, the enhanced noises are not reproducible. 

Please let me know if any additional clarifications are needed. Let me know if you are able to reproduce.

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