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halftga.c
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C/C++ Source or Header
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1991-05-16
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3KB
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133 lines
/*********************************************************
HALFTGA.C - Shrinks a TARGA file to exactly 1/2 its size
and modifies the header appropriately.
By Aaron A. Collins, written on 3/30/90
Note - Does NOT interpolate color values!!
This is to complement PICLAB's inter-
polating "RESIZE" command...
This file is released to the Public Domain.
PICLAB is a trademark of The Stone Soup Group.
TARGA is a trademark of AT&T/Truevision.
Revised 5/15/91 - AAC - Version 1.1 - Removed IBM-ness of
filenames/exts.
**********************************************************/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define MAXXRES 2048 /* huge max x resolution allowable, infinite y res. */
unsigned char linbuf[MAXXRES * 3];
void main(argc,argv)
int argc;
char *argv[];
{
int xres, yres, xhi, yhi;
register int x, y;
FILE *in, *out;
printf("\n\nTARGA-24 Image File 1/2 Size Resolution Reducer\n");
printf("Version 1.1 By Aaron A. Collins. Written 3/30/90 Revised 5/15/91\n\n");
if (argc != 3)
{
printf("Usage: %s InputFile OutputFile\n\n",argv[0]);
exit(1);
}
if ((in = fopen(argv[1], "rb")) == NULL) /* try w/supplied ext. */
{
printf("ERROR - Couldn't open file %s\n", argv[1]);
exit(1);
}
if ((out = fopen(argv[2], "wb")) == NULL)
{
printf("ERROR - Couldn't create file %s\n", argv[2]);
fclose(in);
exit(1);
}
/** Copy 1st part of standard Targa header **/
for (x = 0; x < 12; x++) /* 00, 00, 02, then 9 00's... */
fputc(fgetc(in), out);
/** load x and y resolution, and rewrite as rest of Targa hdr **/
xres = fgetc(in); /* lo order */
xhi = fgetc(in); /* hi order */
xres += ((unsigned int) xhi) << 8;
if (xres > MAXXRES) /* too big? */
{
printf("ERROR - X res. of %s (%d) exceeds maximum (%d)!\n", argv[1], xres, MAXXRES);
fclose(in); /* close files */
fclose(out);
unlink(argv[2]); /* delete empty out file */
exit(1);
}
xhi = xres; /* save old resolution */
xres >>= 1; /* cheapie divide by two! */
fputc(xres & 0x00ff, out); /* write lo order */
fputc((xres & 0xff00) >> 8, out); /* write lo order */
yres = fgetc(in); /* now do yres the same... */
yhi = fgetc(in);
yres += ((unsigned int) yhi) << 8;
yhi = yres;
yres >>= 1;
fputc(yres & 0x00ff, out);
fputc((yres & 0xff00) >> 8, out);
fputc(fgetc(in), out); /* 24 bits/pixel (16 million colors!) (24) */
fputc(fgetc(in), out); /* Set bit to indicate top-down display (32)*/
printf("\nInput file = %s\n", argv[1]); /* show stats */
printf("Output file = %s\n\n", argv[2]);
printf("Old X resolution = %d\n", xhi);
printf("Old Y resolution = %d\n\n", yhi);
printf("New X resolution = %d\n", xres);
printf("New Y resolution = %d\n\n", yres);
printf("Processing Line: 0");
for (y = 0; y < yhi; y++) /* for every line in the old file */
{
printf("\b\b\b%3d", y); /* disp. current line # */
fread(linbuf, 3, xhi, in); /* read in a whole line */
if (feof(in)) /* stop if file truncated */
break;
if (y & 0x0001) /* throw away odd # lines */
continue;
for (x = 0; x < xhi; x++) /* for every BGR triplet */
{
if (x & 0x0001) /* throw away odd # BGR's */
continue;
fwrite(&linbuf[x * 3], 3, 1, out); /*write BGR trip*/
}
}
printf("\n");
fclose(in); /* close files */
fflush(out);
fclose(out);
exit(0);
}