ImageMagick-6.9.6-6 exact gradient colors

[Danack]

Hi,

Someone tested ImageMagick 6.9.6-6 against PHP Imagick's set of tests and found an issue: Imagick/imagick#187

It seems that from this bug report
https://www.imagemagick.org/discourse-server/viewtopic.php?f=3&t=30570 a change was committed:
d75ed24

That change, has altered the colors of pixels that are generated for a black-white gradient.

What this test is doing is creating a 256x256 image, that is a gradient from black to white. It then checks that each of the pixels is the correct color, on the assumption that they should be 0/255, 1/255, 2/255,....., 255/255

The colors are slightly off for each pixel, other than the black one. At the white end of the gradient, the color is not 255/255 but is instead 0.99609369039445.

According to the reporter, this issue does not affect ImageMagick 7.

[mikayla-grace]

Thanks for the problem report. We can reproduce it and will have a patch to fix it in GIT master branch @ https://github.com/ImageMagick/ImageMagick later today. The patch will be available in the beta releases of ImageMagick @ http://www.imagemagick.org/download/beta/ by sometime tomorrow.

[Danack]

Thanks. Looks fixed for the existing tests.

I'm going to try to setup another test for the 'diagonal' gradient, but will do that at a later date.