2008.09.10 19:48 "RE: [Tiff] SAMPLEFORMAT_IEEEFP", by Chris Cox

The info palette reads out exact values from the file, unaffected by any display transforms. (so if you change the display exposure, the values still read out the same).

If you want to see the floating point values in the info palette, set the readout to show 32 bit values (right now you have 16 bit values showing). Apparently you missed the documentation on how to use the Info palette.

The loss of contrast could be due to gamma encoding (32 bit data in Photoshop is always gamma 1.0), or a problem with your display profile (since Photoshop always converts from the document profile to your display profile for accurate image viewing).

The TIFF file has no limits specified, it just provides the data.

The zero to one range for viewing is just a default, and a convention found in many HDR images.

Chris

-----Original Message-----

From: tiff-bounces@lists.maptools.org on behalf of acanicio

Hello Chris and all,

Yes, I had tried to rescale using the sliders but, since all the RGB values were all 32767 in the "Info" window in photoshop, there was no way to change anything with that.

Anyway, as suggested, I did the changes in my program last evening, rescaling the color values between 0 and 1 when writing the tiff file.

Then I opened the file in photoshop, and... SHAZAAAM!! it worked!!! The image was exactly as the original. The difference is that the resulting image is a bit washed out (lighter) than the original.

Chris, you say that the limits don't have to be between zero and one. But how do you specify that in the TIFF file? Is there a specific tag I have to use?

Thanks again for your help and your patience.

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.

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