Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Jump to bottom

Canvas RGBA pixel values are inaccurate (alpha premultiplication?) #25

Open
joedf opened this issue Mar 26, 2023 · 1 comment
Open

Canvas RGBA pixel values are inaccurate (alpha premultiplication?) #25

joedf opened this issue Mar 26, 2023 · 1 comment
Labels
bug Something isn't working VnV Verification and Validation

Comments

@joedf
Copy link
Owner

joedf commented Mar 26, 2023

Look into canvas alpha premultiplication issues?
https://stackoverflow.com/a/42294622/883015

Causes thing like black pixels (0x000000) be read as (0x010101), or (0x808080) as (0x767676)...
Noticed from unit testing the image metrics (js-tests)...
Output values were off because of this?
@joedf joedf added bug Something isn't working VnV Verification and Validation labels Mar 26, 2023
@joedf
Copy link
Owner Author

joedf commented Apr 13, 2023

https://html.spec.whatwg.org/multipage/canvas.html#premultiplied-alpha-and-the-2d-rendering-context

Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment
Assignees
No one assigned
Labels
bug Something isn't working VnV Verification and Validation
Projects
None yet
Milestone
No milestone
Development

No branches or pull requests
1 participant
@joedf