Re: contrast shrink?

On Tue, 30 Mar 2010 22:57:34 -0400
[email protected] wrote:

| I use ImageMagick a LOT.
| Thanks for a great program.
| 
| I use
| convert imagein -channel all -contrast-stretch 0x0 imageout
| on raw film scans to expand the histogram prior to gui editing. 
| Sometimes I'd like to shrink/de-contrast an image.
| like
| convert imagein -channel all -contrast-stretch -1%%x-1%% imageout
| But negative arguments to -contrast-stretch seem to be ignored, with no 
| complaint, and no effect on the image.
| 
| Can I achieve a contrast shrink some other way?
| TIA
| 

+level 1%

See IM examples, Color Modifications, Reversed Level Adjustments

Instead of -contrast-stretch 0  you should use -auto-level which.
the former stretched 'binned' history values, the later uses exact
maximum and minimum values.

It is not well documented yet as their is still work to be done in
the 'Histogram Modification' area, and the current operators are
a little all over the place.



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