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February 2004
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2004.02.06 21:35 "displaying 12 bit tiff image", by Liliana Resendiz
Hello,
I'm BCB6 user, I've reading the documentation in order to display correctly
a 12-bit image on a TImage, first i proved with this code
TIFF* tif = TIFFOpen(FileName, "rl");
int max = 0;
if (tif)
{
uint32 w, h, nOffset;
size_t npixels;
uint32* raster;
uint16 pixel_val;
unsigned short tfBitsPerSample, tfSamplesPerPixel,
tfPlanarConfiguration,
tfPhotometricInterpretation, tfGrayResponseUnit,
tfImageDepth, tfBytesPerRow;
TIFFGetField(tif, TIFFTAG_PHOTOMETRIC, &tfPhotometricInterpretation);
TIFFGetFieldDefaulted(tif, TIFFTAG_BITSPERSAMPLE, &tfBitsPerSample);
TIFFGetFieldDefaulted(tif, TIFFTAG_SAMPLESPERPIXEL, &tfSamplesPerPixel);
TIFFGetFieldDefaulted(tif, TIFFTAG_PLANARCONFIG,
&tfPlanarConfiguration);
TIFFGetFieldDefaulted(tif, TIFFTAG_GRAYRESPONSEUNIT,
&tfGrayResponseUnit);
tfImageDepth = tfBitsPerSample * tfSamplesPerPixel;
nOffset = TIFFCurrentDirOffset( tif );
TIFFGetField(tif, TIFFTAG_IMAGEWIDTH, &w);
TIFFGetField(tif, TIFFTAG_IMAGELENGTH, &h);
npixels = w * h;
raster = (uint32*) _TIFFmalloc(npixels * sizeof(uint32));
if (raster != NULL)
{
if (TIFFReadRGBAImage(tif, w, h, raster))
{
for (int y = 0; y < h; ++y)
{
pixel_val = (uint16) *raster++;
pixel_val = pixel_val;
if (pixel_val > max)
max = pixel_val;
}
}
_TIFFfree(raster);
}
TIFFClose(tif);
}
with the TIFFReadRGBAImageOriented(tif, w, h, raster)) function, and i tried
to display it on a TImage but it handles data range [0,256], but doing
pixel_val = (uint16) *raster++, It seems i get a pixel value with data range
[0,4096], is it correct?. I opened the image with the "rl" parameters to get
the max pixel value of 3855, but now, how i can display int on a Timage?
If i direclty open the tiff image from the TImage and change its pixel
format to pf16bit then it displays something but it is not correclty at all.
I imagine that the TImage assumes a data range [0,256] and tries to display
it as an 8-bit image because it appears black.
Can you help me to display it correctly?
Thank you in advance.
Liliana