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2004.01.05 20:09 "Re: Resampled TIFF doesn't open in viewer", by Andrey Kiselev
Hi,
On Sat, Jan 03, 2004 at 05:17:41PM -0600, Pushkar Pradhan wrote:
> I resample a TIFF image (striped, 8 bits/sample, separate image
> planes, 1 band, width: 621, height : 577, rows/strip 13) by a factor
> of 2 using Nearest Neighbor method. Thus image width and height
> increase by 2. Moreover, I make the o/p format IEEE FP. However, my
> viewer is unable to open the image (reports it's own errors). I
> correctly set the rows/strip tag to 26 as it is 13 in the input image.
You can set _any_ RowsPerStrip value for output image, because this
parameter completely unrelated to the input one, it is only determined
by the output image characteristics.
I have attached the sample code to read 8-bit image, process it and
write out in form of floating point values.
> I don't think I have to worry about stripbytecounts and stripoffsets
> as they cannot be set. But do I need to read these tags from the input
> image and use it somehow?
No, they are used internally by libtiff.
> Magic: 0x4949 <little-endian> Version: 0x2a
> Directory 0: offset 484388 (0x76424) next 0 (0)
> ImageWidth (256) SHORT (3) 1<1242>
> ImageLength (257) SHORT (3) 1<1154>
> BitsPerSample (258) SHORT (3) 1<32>
> Compression (259) SHORT (3) 1<1>
> Photometric (262) SHORT (3) 1<1>
> StripOffsets (273) LONG (4) 45<8 32300 64592 96884 129176 161468 193760
> 226052 258344 290636 322928 355220 387512 419804 452096 0 0 0 0 0 0 0 0 0
^^^^^^^^^^^^^^^^^^
> ...>
> SamplesPerPixel (277) SHORT (3) 1<1>
> RowsPerStrip (278) SHORT (3) 1<26>
> StripByteCounts (279) LONG (4) 45<32292 32292 32292 32292 32292 32292 32292
> 32292 32292 32292 32292 32292 32292 32292 32292 0 0 0 0 0 0 0 0 0 ...>
^^^^^^^^^^^^^^^^^^
Looks like something goes wrong in your code. Please, chack out attached
example.
Andrey
--
Andrey V. Kiselev
Home phone: +7 812 5274898 ICQ# 26871517
#include <stdio.h>
#include <stdlib.h>
#include "tiffio.h"
int main (int argc, char **argv)
{
unsigned int i;
TIFF *in, *out;
uint16 spp, bpp, photo;
uint32 image_width, image_height, npixels;
tsize_t instripsize, outstripsize;
tstrip_t instrips, outstrips;
u_char *inbuf, *outbuf;
if (argc < 3)
{
fprintf(stdout, "Usage: %s infile.tif outfile.tif\n", argv[0]);
return 1;
}
/****************************************************************************/
/* Open input file and get image characteristics. */
/****************************************************************************/
in = TIFFOpen(argv[1], "r");
if (!in)
{
fprintf (stderr, "Can't open %s for reading\n", argv[1]);
return 2;
}
TIFFGetField(in, TIFFTAG_IMAGEWIDTH, &image_width);
TIFFGetField(in, TIFFTAG_IMAGELENGTH, &image_height);
TIFFGetField(in, TIFFTAG_BITSPERSAMPLE, &bpp);
TIFFGetField(in, TIFFTAG_SAMPLESPERPIXEL, &spp);
TIFFGetField(in, TIFFTAG_PHOTOMETRIC, &photo);
if (bpp != 8)
{
fprintf (stderr, "Only 8bit input data supported.\n");
TIFFClose(in);
return 3;
}
instripsize = TIFFStripSize(in);
npixels = image_width * image_height * spp;
instrips = TIFFNumberOfStrips(in);
inbuf = malloc(npixels * bpp/8); /* Should be equal to iinnstripsize*instrips */
outbuf = malloc(npixels * sizeof(float));
/****************************************************************************/
/* Read input data. We will read the full image in memory. */
/****************************************************************************/
for (i = 0; i < instrips; i++)
TIFFReadEncodedStrip(in, i, (tdata_t)(inbuf + i * instripsize),
instripsize);
/****************************************************************************/
/* Perform processing. In our example we just multiply band values */
/* and their band numbers (1 based). */
/****************************************************************************/
for (i = 0; i < npixels; i++)
((float *)outbuf)[i] = (float)inbuf[i] * (float)(i % spp + 1);
/****************************************************************************/
/* Open output file and prepare it for writing. */
/****************************************************************************/
out = TIFFOpen(argv[2], "w");
if (!in)
{
fprintf (stderr, "Can't open %s for writing\n", argv[2]);
return 4;
}
TIFFSetField(out, TIFFTAG_IMAGEWIDTH, image_width);
TIFFSetField(out, TIFFTAG_IMAGELENGTH, image_height);
TIFFSetField(out, TIFFTAG_BITSPERSAMPLE, sizeof(float) * 8);
TIFFSetField(out, TIFFTAG_SAMPLESPERPIXEL, spp);
TIFFSetField(out, TIFFTAG_PLANARCONFIG, PLANARCONFIG_CONTIG);
TIFFSetField(out, TIFFTAG_PHOTOMETRIC, photo);
TIFFSetField(out, TIFFTAG_SAMPLEFORMAT, SAMPLEFORMAT_IEEEFP);
TIFFSetField(out, TIFFTAG_ROWSPERSTRIP, TIFFDefaultStripSize(out, 0));
outstripsize = TIFFStripSize(out);
outstrips = TIFFNumberOfStrips(out);
/****************************************************************************/
/* Write data out. */
/****************************************************************************/
for (i = 0; i < outstrips; i++)
TIFFWriteEncodedStrip(out, i, (tdata_t)(outbuf + i * outstripsize),
outstripsize);
/****************************************************************************/
/* Clean all and exit. */
/****************************************************************************/
_TIFFfree(inbuf);
_TIFFfree(outbuf);
TIFFClose(out);
TIFFClose(in);
return 0;
}