Fred Weinhaus on wrote...
| I would discuss your problem with Anthony. I am told that you can
| compile IM into a 32-bit version Q32 called HDRI (I think) and that
| this might work to solve your problem. Discuss this with Anthony.
|
When dealing with complex image processing like this you are pretty well
beyond practical use of the command line.
First you get 'quantization' problems whenever the data gets stored back
into the image format afetr each individual operation. Especially at a
Q8 IM. And while you can improve things by going to a Q16, Q32 or even
Q64 you still have a bigger problem.
You also have a 'clipping' problme in that a image value is saved into
an interger of the size of the compiled 'Q' depth of the IM, so that
zero represents the low range and 'QuantiumRange' (an -fx and Magick
Core term) for the high range limit. any results outside this range
will be 'clipped' to that limit (representing the 0.0 to 1.0 image
value.) You can no hold negative or greater than 1 values.
Recently IM has added a new storage format HDRI where 'doubles' or
floating point numbers are used instead. These do not have clipping
limits and have a extrememly low 'quantization' problem.
Values generated will be stored correctly between the image operations
and will only be clipped when the image is finally written to a format
that can not use floating point values (Currently MIFF and OpenEXP
formats).
WARNING: there are probably some operations that still do internal
quantization and or rounding, and these are being fixed as they are
found.
HDRI was invented to allow you to create images with a dynamic change in
contrast handling between; foreground - background; shadowed - bightly
lit; areas producing an image that is more in line with what we humans
see naturally. However the same thing produces better processing of
image operations, as clipping is removed.
Anthony Thyssen ( System Programmer ) <[EMAIL PROTECTED]>
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Never ask them for an explaination. You only end up worse confused.
-- Rick Cook, "Wizardry Cursed"
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Anthony's Home is his Castle http://www.cit.gu.edu.au/~anthony/
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