Questions and postings pertaining to the usage of ImageMagick regardless of the interface. This includes the command-line utilities, as well as the C and C++ APIs. Usage questions are like "How do I use ImageMagick to create drop shadows?".
6 posts • Page 1 of 1
I have a request from a user to adjust the blue channel from 1.00 to 1.13 as in Photoshop. I understand that the -level operator is to be used, but can someone explain to me the correct usage of that operator in this context. Unfortunately, my graphics understanding is limited. Thanks for any info anyone can provide to enlighten me on how to achieve the desired effect.
- Posts: 11796
- Joined: 2010-01-23T23:01:33-07:00
- Authentication code: 1151
- Location: England, UK
Even if I used Photoshop (which I don't), I'd need more information than that. Which PS operation is used? What PS measurement gives "1.00" or "1.13"?centesimiae wrote:I have a request from a user to adjust the blue channel from 1.00 to 1.13 as in Photoshop.
snibgo's IM pages: im.snibgo.com
From my limited understanding, Photoshop has a channel mixing interface that you can use to adjust individual channels. I am thinking that those numbers translate to a 13% increase of the blue channel in the image. Sorry, that's all I understand at the moment. I'll try to post more once I do some more research. I was hoping someone could give me a laymen's explanation on how to use the -level operator.
- Posts: 25124
- Joined: 2007-07-02T17:14:51-07:00
- Authentication code: 1152
- Location: Sunnyvale, California, USA
It is the channel mixer in PS, where they use percent, so 113% which translates to multiply by 1.13. It has nothing to do with -level. For that see http://www.imagemagick.org/Usage/color_mods/#levels