Using: Imagemagick 6 (though from a cursory look, v7 might also have the same issue).
Our custom code runs the following command through ImagemagickExecManager, to get an RGB value back on STDOUT. Notably, this has no destination file. The return value on STDOUT is something like
$ convert /PATH/TO/INPUTFILE[0] -resize 1x1\! -format "%[fx:int(255*r+.5)],%[fx:int(255*g+.5)],%[fx:int(255*b+.5)]" info:-
"129,136,137"
Since 📌 Switch command line escaping to Symfony Process Fixed (i.e. post 8.x-3.6) this does not work anymore, because the destination file is always added to the command. Adding an empty destination file leads to the following (you can try on CLI):
$ convert /PATH/TO/INPUTFILE[0] '-resize' '1x1!' '-format' '"%[fx:int(255*r+.5)],%[fx:int(255*g+.5)],%[fx:int(255*b+.5)]"' 'info:-' ''
convert: no decode delegate for this image format `INFO' @ error/constitute.c/ReadImage/572.
����JFIF``��;CREATOR: gd-jpeg v1.0 (using IJG JPEG v80), quality = 75
��C
$.' ",#(7),01444'9=82<.342��C
2!!22222222222222222222222222222222222222222222222222�"����������
?����(The "convert:" line is STDERR, the rest is STDOUT.)
Remove the final '' from the command, if $destinationFile is empty; then it works again.
Active
4.0
Code
Seeing that graphicsmagick convert works the same way, so I added the same change to buildGraphicsmagickConvertCommand().
I only tested manually on Imagemagick 6, that this fixes our issue.