Issue 438 in webp: Image loses color/brightness after converting to webp

[azam… via monorail]

Status: New
Owner: ----
Labels: Type-Defect Priority-Medium

New issue 438 by azam...@gmail.com: Image loses color/brightness after converting to webp
https://bugs.chromium.org/p/webp/issues/detail?id=438

What steps will reproduce the problem?
1. Convert the image using cwebp
2. Use nearly any arrangement of arguments
3. You can noticably see the stars lose color and/or dimming in the resulting webp image.

What is the expected output? What do you see instead?
I am trying to confirm the image to webp while keeping the colors/brightness all visually intact.

What version of the product are you using? On what operating system?
Linux 19.04 & cwebp

Please provide any additional information below.
I tried nearly 30 different combinatations of arguments, no matter what I do the resulting webp image looks different than the source png image.
The source png image is a hubble photo of the cosmos.
Currently my arguments are -lossless -sharp_yuv -exact -mt

I am more concerned with preserving the color/look of the image than with compression at this point, any advice would be highly appreciated!

Attachments:
source.png 697 KB
output.webp 33.1 KB

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[azam… via monorail]

Comment #1 on issue 438 by azam...@gmail.com: Image loses color/brightness after converting to webp
https://bugs.chromium.org/p/webp/issues/detail?id=438#c1

For interest sake the original image was taken from here https://hubblesite.org/contents/media/images/2019/17/4493-Image.html

[ygu… via monorail]

Comment #2 on issue 438 by ygu...@google.com: Image loses color/brightness after converting to webp
https://bugs.chromium.org/p/webp/issues/detail?id=438#c2

It seems your source.png contains an sRGB color profile that is not kept by default. Try the cwebp option "-metadata icc" or "-metadata all".
I attached the output of the following command, please verify that it fixes the issue:
cwebp source.png -lossless -metadata all -z 9 -o source.webp

Attachments:
source.webp 389 KB

[azam… via monorail]

Comment #3 on issue 438 by azam...@gmail.com: Image loses color/brightness after converting to webp
https://bugs.chromium.org/p/webp/issues/detail?id=438#c3

Thank you very much! That seems to work perfectly, nice added bonus is that the resulting image is still much smaller than the original.