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https://issues.apache.org/jira/browse/IMAGING-147?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14266693#comment-14266693
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Stephan Köninger edited comment on IMAGING-147 at 1/6/15 8:39 PM:
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Hi,
I have created another patch file which is based on the current SVN trunk
(instead of GIT head - sorry for that). I corrected the copy past error.
The "odd" values are a result of color model conversions. For instance: If one
wants to convert the color red which is (255,0,0) in RGB to XYZ color model,
one has to use a formula as follows:
(Assumption: White point is D65 and observer 2° as stated in ColorConversion
line 85)
{noformat}
[ X ] [ 0.4124 0.3576 0.1804 ] [ R ]
[ Y ] = [ 0.2127 0.7152 0.0722 ] * [ G ]
[ Z ] [ 0.0193 0.1192 0.9502 ] [ B ]
{noformat}
(Hint: The given matrix is based on sRGB color space:
http://www.brucelindbloom.com/index.html?Eqn_RGB_XYZ_Matrix.html)
So color red will be 41.24, 21.26, 1.93. Other colors like Luv are now derived
from this XYZ values and so on.
Regards
Stephan
was (Author: stephan.koeninger):
Hi,
I have created another patch file which is based on the current SVN trunk
(instead of GIT head - sorry for that). I corrected the copy past error.
It would be nice to add a "convertTo" method to all color classes, which is
able to convert a color to other color models. By adding documentation to this
method it will be much clearer why the values for color models like Luv look
odd to you.
Regards
Stephan
> Color constants
> ---------------
>
> Key: IMAGING-147
> URL: https://issues.apache.org/jira/browse/IMAGING-147
> Project: Commons Imaging
> Issue Type: Improvement
> Components: imaging.color.*
> Reporter: Benedikt Ritter
> Labels: github
> Fix For: Review Patch
>
> Attachments: IMAGING-147_001.patch, IMAGING-147_002.patch
>
>
> The Color classes should provide constants for useful colors like black,
> white and maybe their base colors. For example ColorCmyk could provide
> Constants for black, white, cyan, magenta and yellow ColorCmyk objects.
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