Tests if the 2 images have the same content. Both images must be
defined, have the same width, height, channels and the same color in
each pixel. The color comparison is done at 8-bits per pixel. The
color representation such as direct vs paletted, bits per sample are
not checked. Equivalent to is_image_similar($im1, $im2, 0, $comment).
Tests if the 2 images have similar content. Both images must be
defined, have the same width, height and channels. The cum of the
squares of the differences of each sample are calculated and must be
less than or equal to $maxdiff for the test to pass. The color
comparison is done at 8-bits per pixel. The color representation such
as direct vs paletted, bits per sample are not checked.
Creates 2 test images and writes $text1 to the first image and $text2
to the second image with the string() method. Each call adds 3
ok/not ok to the output of the test script.
Extra options that should be supplied include the font and either a
color or channel parameter.
This was explicitly created for regression tests on #21770.