clipka wrote:
> clipka schrieb:
>> clipka schrieb:
>>> clipka schrieb:
>>>> It appears to me that TIFF file input is broken, leading to a 
>>>> transparent texture when used in an image_map; can someone confirm?
>>>
>>> I should have mentioned that this is about 3.7 (beta.34 to be exact).
>>
>> Apparently, the behavior is different for compressed and uncompressed 
>> files.
> 
> ... and POV-Ray 3.6.2 renders both properly; I presume that this is an 
> issue in the TIFF library: In the POV-Ray 3.6.2 branch, it has been 
> updated to libtiff 3.8.2, while POV-Ray 3.7 still uses libtiff 3.6.1.
> 
> I tried to "transplant" the libtiff 3.8.2 from POV 3.6.2 over to the 
> POV-Ray 3.7 project, but with not much success yet.


POV-Ray supports only a (particular small) subset of possible 
TIF-formats and IIRC there was a change between libtif 3.6 and 3.8 
regarding alpha channels and the recommended way the tag 
'TIFFTAG_EXTRASAMPLES' should be interpreted.

POV-Ray also ignores all colorimetric and gamma correction related tags.
And POV-Ray does not support all the 'interesting' TIF-formats like 
16bps, 24bps, and 32bps floating point HDR anyway.

In fact TIFF support is 'broken' in so many ways that I would drop it 
completely. I can estimate how much time is needed to write some 
reliable TIF importer and I think this time would be better spend for 
the more important things within POV-Ray.

-Ive

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