Converting CMYK to RGB using *magick

Rails
1

Hi, Does anyone have any experience converting CMYK images to RGB/web
using rmagick/mini_magick/imagemagick?

I’m finding that the resulting RGB images look completely different,
they seem to have a green tinge…

fyi, I’m converting using -colorspace RGB, and I’m using imagemagick
directly because the other 2 options seem really slow (by a factor of
20 or so).

I have looked into color profiles, but after trying a few via command
line I noticed that I can’t use the same profiles for all of the
files. Is there any good documentation out there about color profiles?
or is it a bit hit and miss.

I’m a bit of a beginner at this image processing stuff so I might need
a bit of explanation :wink:

2

Jonathan F. wrote:

Hi, Does anyone have any experience converting CMYK images to RGB/web
using rmagick/mini_magick/imagemagick?

I’m finding that the resulting RGB images look completely different,
they seem to have a green tinge…

fyi, I’m converting using -colorspace RGB, and I’m using imagemagick
directly because the other 2 options seem really slow (by a factor of
20 or so).

I have looked into color profiles, but after trying a few via command
line I noticed that I can’t use the same profiles for all of the
files. Is there any good documentation out there about color profiles?
or is it a bit hit and miss.

I’m a bit of a beginner at this image processing stuff so I might need
a bit of explanation :wink:

I recommend asking on a rmagick / imagemagick mailing list.

This stuff is not straightforward.

Stephan

3

Yeah you make a good point :wink: I was kinda just putting feelers out
everywhere looking for anyone who had been through what I’m going
through and could give me some pointers!

Having said that, I have partially solved my problem!

I wasn’t having any luck with profiles because I didn’t have a package
installed called lcms or “Little cms”. Imagemagick uses this to
convert things via color profiles :slight_smile:

fyi, if anyone is having trouble with this (on a mac) then you should
install imagemagick via the following command:

sudo port install imagemagick +lcms

I haven’t tried it on ubuntu yet but it’s bound to be similar

Thanks,
Jonzo.

On Fri, Apr 11, 2008 at 4:15 PM, Stephan W.
[email protected] wrote:

20 or so).

This stuff is not straightforward.

Stephan

Posted via http://www.ruby-forum.com/.

–
Jonathan