imagemagick-convert

I'm trying to do what The GIMP does when selecting "color to alpha" with an actual colour. I've got an image that has the color #a0132e in it, and I want that converted to transparency. Not only that exact colour, but any colour diverting from it, must become that much semi-transparent. That is what "color to alpha" does in GIMP. I've tried a million different things, but I can't get my head around it. I've been frustrating myself for a couple of hours trying the -fx parameter and it's absolutely weird syntax, so that didn't help at all. Perhaps some of the options for convert will do the

I want to create a captcha pic by use convert from ImageMagick. And I follow this , but there are some problem . Input In my linux shell: convert -background white -fill black -font FreeSerif-Bold -pointsize 36 label:'adfgh' ./test.png The Error is: convert:not authorized adfgh @ error/constitute.c/ReadImage/453. convert:missing an image filename ./test.png @ error/convert.c/ConvertImageCommand/3015 My ImageMagick: Version:6.7.2-7 , I install it with yum install ImageMagick . I'm clueless. Any advice please? sNICkerssss Note: the solution in this and other answers involves disabling safety

My supervisor has asked me to convert the parts of our Perl scripts that use PerlMagick to instead pipe and use the command line version of ImageMagick (for various unrelated reasons). Using the our existing interface (crop, scale, save, etc) I'm building up a list of operations the user wants to perform on an image, constructing the statement to pipe and then executing it. What I would like to know is: Are convert operations performed from left to right? ie the order I pass them What happens if I pass the same option twice? Are they performed separately? Obviously the order in which