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September 2008
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2008.09.10 00:06 "Re: SAMPLEFORMAT_IEEEFP", by Chris Cox
They don't have to be between zero and one - but that is the default viewing range. There are adjustments to change the value ranges, and a viewing exposure slider to change the viewing exposure. I mean use the adjustment named Exposure in Photoshop to scale the data. If that works, then you can scale it when doing your conversion. Chris On 9/9/08 12:02 AM, "acanicio" <acanicio@astrosnap.com> wrote: > > Dear Bruce and Chris, > > Thank you ! > I didn't know that floating point values had to be between 0 and 1 !! > When converting to float, I kept the original range, i.e. 0..255 when coming > from 8 bits, 0..65535 when coming from 16 bits, and 0..4294967295. > > What do you mean by "Use the exposure adjustment " ? Is there some specific > tag for this or is it the same thing as scaling down ?. I see tag > TIFFTAG_REFERENCEBLACKWHITE in the specifications. Is that it ? > > I'll try as you say, thank you very much to both of you. > > Best regards > Axel > > > > > Chris Cox wrote: >> >> >> Use the exposure adjustment and scale the values down. >> >> Most of the time, you should scale your white point to something near 1.0 >> to >> ensure visibility. >> >> Chris >> >> >> >> >> >> On 9/7/08 4:18 PM, "acanicio" <acanicio@astrosnap.com> wrote: >> >>> But I have no luck with floating point values. I use SAMPLEFORMAT_IEEEFP >>> sample format along with 32 bits per sample. >>> All the pixel values are issued from an 8 bit/sample image, with no >>> conversion or multiplication applied to them. >>> When I open the file with some well known image editor, the image is >>> completely saturated, all white with values 32767... >>> Where should I look ? >> >> _______________________________________________ >> Tiff mailing list: Tiff@lists.maptools.org >> http://lists.maptools.org/mailman/listinfo/tiff >> http://www.remotesensing.org/libtiff/ >> >>