Re: Converting to a single-color image (duotone sans black channel)

On Mon, 14 Jun 2010 21:17:11 -0700
[email protected] wrote:
| >Hello,
| >
| >Apologies if I'm missing something obvious, I'm trying to work out 
| >how to convert an image to a single colour - much like grayscale but 
| >colorised. Effectively what I'm trying to do is replicate the effect 
| >of Photoshop's Screen blending mode when the top layer is a solid 
| >color. I've put up an example to compensate for my inability to 
| >articulate this properly here: http://sho.ch/otterconvert.jpg
| >
| >I can do a duotone easily enough but this has me stumped. It would 
| >also make my life notably easier if it was a single invocation of 
| >convert.
| >
| >Any guidance would be greatly appreciated.
| 
| 
| see -tint and related techniques at 
| http://www.imagemagick.org/Usage/color/#tinting
| 
| also if you are on unix, see my script tintilize at 
| http://www.fmwconcepts.com/imagemagick/index.php
| 
| 
| Fred
| 
| 
| P.S.  On second thought after re-reviewing your example, a better 
| method would appear to be
| 
| +level-colors blue,white
| 
| see http://www.imagemagick.org/Usage/color/#level-colors

Note you should greyscale the image first then apply +level-colors

Remember +level-colors is still a -level operator, just getting its
values (+level -> map black and white to given levels) from the colors
you have specified.  each channel will still be modified individually.

So use...
   -colorspace Gray +level-colors blue,white

You can also use -gamma afetr the -colorspace operator to adjust the
mid-tone brightness, if you want to.

    

  Anthony Thyssen ( System Programmer )    <[email protected]>
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