[magick-users] Level

[Anthony Thyssen]

On Thu, 21 May 2009 16:12:55 -0400
Steve Stachurski <sstachurski at lorsstudio.com> wrote:

| Hello-
| 
| I'm seeking some more information regarding the Level method that can be 
| performed to manipulate an image. I have tried dozens of different 
| ranges of black and white points, and I always get an image that is 
| either all white or all black. I have tried setting my black points 
| anywhere from 0 to 0.7 and my white points anywhere from 0.3 to 1.0.
| 
| I'm using PerlMagick to to this. There is a parameter to the Level 
| method, "levels," which takes a string, but I have no idea what kind of 
| string goes here.
| 
Two things.

You may be better asking in the IM Forums
   http://www.imagemagick.org/discourse-server/viewtopic.php?f=1

and secondly an example would be good.

Also have you first tried to use the command line -level operator
so you can understand what you are doing.

IM examples,  Color Modifications,  Direct Level Adjustments
   http://www.imagemagick.org/Usage/color/#level
Also look at the newer varients such as using +level (or adding a '!'
flag for Perl magick arguments)  and  -level-colors.

NOTE: using values like 0.3 and 1.0 probably produce black as it is
expecting values in the range from   0 to Quantumrange.  EG   65535
as such your values are all near zero and thus 'near black'.



  Anthony Thyssen ( System Programmer )    <A.Thyssen at griffith.edu.au>
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    When someone tells me to go fly a kite I say 
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     Anthony's Home is his Castle     http://www.cit.gu.edu.au/~anthony/