Merged
Conversation
The default form of XYB has X = B = 0 for achromatic colors. This was
done by altering the XYB transform matrix to do the LMS to XYB
conversion and apply B - Y, but we had done so incorrectly. The matrix
that incorporates this change should have been:
XYB_LMS_TO_XYB = [
[0.5, -0.5, 0.0],
[0.5, 0.5, 0.0],
[-0.5, -0.5, 1.0]
]
We mistakenly applied the logic in reverse applying to the forward
transform which should have been in the inverse transform and vice
versa. It resulted in the same X = B = 0, but non achromatic colors
were not quite right.
With all of that said, instead of using a clever matrix to do the XYB
transform and subtract Y from B, we now use the standard matrix and then
just subtract Y from B at the end. We verified both were equivalent, but
the later approach makes it more clear what we are doing.
gir-bot
added
S: needs-review
Owner
Author
|
@gir-bot lgtm |
gir-bot
added
S: approved
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
2 participants
Add this suggestion to a batch that can be applied as a single commit.This suggestion is invalid because no changes were made to the code.Suggestions cannot be applied while the pull request is closed.Suggestions cannot be applied while viewing a subset of changes.Only one suggestion per line can be applied in a batch.Add this suggestion to a batch that can be applied as a single commit.Applying suggestions on deleted lines is not supported.You must change the existing code in this line in order to create a valid suggestion.Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be applied on multi-line comments.Suggestions cannot be applied while the pull request is queued to merge.Suggestion cannot be applied right now. Please check back later.
The default form of XYB has X = B = 0 for achromatic colors. This was done by altering the XYB transform matrix to do the LMS to XYB conversion and apply B - Y, but we had done so incorrectly. The matrix that incorporates this change should have been:
XYB_LMS_TO_XYB = [
[0.5, -0.5, 0.0],
[0.5, 0.5, 0.0],
[-0.5, -0.5, 1.0]
]
We mistakenly applied the logic in reverse applying to the forward transform which should have been in the inverse transform and vice versa. It resulted in the same X = B = 0, but non achromatic colors were not quite right.
With all of that said, instead of using a clever matrix to do the XYB transform and subtract Y from B, we now use the standard matrix and then just subtract Y from B at the end. We verified both were equivalent, but the later approach makes it more clear what we are doing.