2004.01.15 18:59 "Re: [Tiff] How to determine number of colors in the colormap", by Bill Cassanova
Thanks for writing.
I wondered about the -1 as well but I saw it in an example and thought I was missing something. The original example was at:
http://remotesensing.org/pipermail/tiff/2003-November/000230.html
So to read the colormap am I doing it correctly? For some reason the results I am getting are non-sensible. I would have expected to see values in the range of 0 to 255.
Instead I am seeing results like from the execution of the code below:
bitspersample: 8
num_entries: 255
0 0 0
26214 26214 26214
39321 39321 39321
52428 52428 52428
65535 65535 65535
39321 52428 65535
26214 52428 65535
13107 52428 65535
The code from the original is posted below for convenience.
uint16 *red;
uint16 *green;
uint16 *blue;
int num_entries = (1 << bitspersample) - 1;
cout << "num_entries: " << num_entries << endl;
// get the photmetric interpretation
if ((result =
TIFFGetField(image_in, TIFFTAG_COLORMAP, &red, &green, &blue)) != 1)
{
return (false);
}
else
{
for (int i = 0; i < num_entries; i++)
{
cout << red[i] << "\t" << green[i] << "\t" << blue[i] << endl;
}
}
Thanks,
Bill