With regard to my suggestion for using -contrast-stretch, I would
note that it also uses a histogram to stretch the image.
The other way to do this is to feed the min and max image values to
-level. Anthony Thyssen has recently greatly improved this function.
So in unix with a shell, you could do (in IM 6.3.9-1 or higher)
min=`identify -format "%[min]"`
max=`identify -format "%[max]"`
convert <inputimage> -level ${min},${max} <outputimage>
That would be the most exact method for stretching the image so that
it just exactly spans the range from 0 to QuantumRange, i.e. from
full black to full white.
See notes about -level (and +level) at
http://www.imagemagick.org/Usage/color/#contrast
>To the best of my knowledge, -normalize is what it is. The issue is
>that it forces 2% of the dark data and 1% of the light data to be
>fully black and fully white. Thus it will be image dependent whether
>it helps or hurts your image.
>
>If you want to stretch an image so that its min and max values become
>black and white without burning-out this extra 2% at the low end and
>1% at the high end, you can use
>
>convert <image> -contrast-stretch 0 <output>
>
>Normalize is a subset of -contrast-stretch and is equivalent to
>-contrast-stretch 2%x99%
>
>see http://www.imagemagick.org/script/command-line-options.php#normalize
>
>
>
>
>
>>I just started using the normalize function to normalize my images.
>>It's usually very impressive and a big improvement over non-normalized
>>images. Some of the images are worse though, especially images that
>>are predominantly one color, especially red. Is the normalize
>>function being improved, or is it a static sort of a function that
>>either works well on an image or doesn't?
>>
>>- Grant
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