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/******************************************************************************
pamdeinterlace
*******************************************************************************
De-interlace an image, i.e. select every 2nd row.
By Bryan Henderson, San Jose, CA 2001.11.11.
Contributed to the public domain.
******************************************************************************/
#include "pm_c_util.h"
#include "pam.h"
#include "shhopt.h"
#include "mallocvar.h"
enum evenodd {EVEN, ODD};
struct cmdlineInfo {
/* All the information the user supplied in the command line,
in a form easy for the program to use.
*/
const char *inputFilespec; /* Filespecs of input files */
enum evenodd rowsToTake;
};
static void
parseCommandLine(int argc, char ** argv,
struct cmdlineInfo *cmdlineP) {
/*----------------------------------------------------------------------------
Note that the file spec array we return is stored in the storage that
was passed to us as the argv array.
-----------------------------------------------------------------------------*/
optStruct3 opt; /* set by OPTENT3 */
optEntry * option_def;
unsigned int option_def_index;
unsigned int takeeven, takeodd;
MALLOCARRAY_NOFAIL(option_def, 100);
option_def_index = 0; /* incremented by OPTENT3 */
OPTENT3(0, "takeeven", OPT_FLAG, NULL, &takeeven, 0);
OPTENT3(0, "takeodd", OPT_FLAG, NULL, &takeodd, 0);
opt.opt_table = option_def;
opt.short_allowed = FALSE; /* We have no short (old-fashioned) options */
opt.allowNegNum = FALSE; /* We have no parms that are negative numbers */
pm_optParseOptions3(&argc, argv, opt, sizeof(opt), 0);
/* Uses and sets argc, argv, and some of *cmdlineP and others. */
free(option_def);
if (takeeven && takeodd)
pm_error("You cannot specify both -takeeven and -takeodd options.");
if (takeodd)
cmdlineP->rowsToTake = ODD;
else
cmdlineP->rowsToTake = EVEN;
if (argc-1 < 1)
cmdlineP->inputFilespec = "-";
else if (argc-1 == 1)
cmdlineP->inputFilespec = argv[1];
else
pm_error("You specified too many arguments (%d). The only "
"argument is the optional input file specification.",
argc-1);
}
int
main(int argc, char *argv[]) {
FILE * ifP;
tuple * tuplerow; /* Row from input image */
unsigned int row;
struct cmdlineInfo cmdline;
struct pam inpam;
struct pam outpam;
pnm_init( &argc, argv );
parseCommandLine(argc, argv, &cmdline);
ifP = pm_openr(cmdline.inputFilespec);
pnm_readpaminit(ifP, &inpam, PAM_STRUCT_SIZE(tuple_type));
if (inpam.height < 2 && cmdline.rowsToTake == ODD)
pm_error("You requested to take the odd rows, but there aren't "
"any odd rows in the image - it has only one row - Row 0");
tuplerow = pnm_allocpamrow(&inpam);
outpam = inpam; /* Initial value -- most fields should be same */
outpam.file = stdout;
if (inpam.height % 2 == 0)
outpam.height = inpam.height / 2;
else {
if (cmdline.rowsToTake == ODD)
outpam.height = inpam.height / 2;
else
outpam.height = inpam.height / 2 + 1;
}
pnm_writepaminit(&outpam);
{
unsigned int modulusToTake;
/* The row number mod 2 of the rows that are supposed to go into
the output.
*/
switch (cmdline.rowsToTake) {
case EVEN: modulusToTake = 0; break;
case ODD: modulusToTake = 1; break;
default: pm_error("INTERNAL ERROR: invalid rowsToTake");
}
/* Read input and write out rows extracted from it */
for (row = 0; row < inpam.height; row++) {
pnm_readpamrow(&inpam, tuplerow);
if (row % 2 == modulusToTake)
pnm_writepamrow(&outpam, tuplerow);
}
}
pnm_freepamrow(tuplerow);
pm_close(inpam.file);
pm_close(outpam.file);
return 0;
}
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