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#include <stdio.h>
#include <unistd.h>
#include <string.h>
#include <math.h>
#include <gsl/gsl_spline.h>
#include "pnm.h"
typedef struct {
int n;
unsigned short value[1];
} table_t;
static int
pam_transform(FILE *in_fp, FILE *out_fp,
const struct pnm *in_pnm, table_t **tables);
static table_t*
buildCurve(const char *ctrl_points, int resolution, int maxval);
#define RED 0x1
#define GREEN 0x2
#define BLUE 0x4
static void
usage() {
fprintf(stderr,
"usage: pnmcurve [-rgb] -c <curve>\n"
" -r apply curve to red channel.\n"
" -g apply curve to green channel.\n"
" -b apply curve to blue channel.\n"
" -c <curve> curve to apply. <curve> must be\n"
" of the form x1:y1,x2:y2,x3:y3 where xi:yi are\n"
" control points of a cubic spline curve.\n"
" xi,yi must be in the range [0.0,1.0].\n");
}
int
main(int argc, char **argv) {
int c, i;
char *curve = NULL;
struct pnm in_pnm;
int channels = 0;
table_t *table, *gTable[3];
while ((c = getopt(argc, argv, "rgbc:h")) != EOF) {
switch (c) {
case 'r':
channels |= RED;
break;
case 'g':
channels |= GREEN;
break;
case 'b':
channels |= BLUE;
break;
case 'c':
curve = optarg;
break;
default:
break;
}
}
if (!curve) {
usage();
return 1;
}
if (readPnmHeader(stdin, &in_pnm) != 0) {
fprintf(stderr, "failed to read PNM file\n");
return 1;
}
if (in_pnm.maxval != 255 && in_pnm.maxval != 65535) {
fprintf(stderr, "unsupported PNM maxval %d\n", in_pnm.maxval);
return 1;
}
if (channels == 0) channels = RED | GREEN | BLUE;
table = buildCurve(curve, in_pnm.maxval + 1, in_pnm.maxval);
if (!table) {
fprintf(stderr, "could not build table.\n");
exit(1);
}
gTable[0] = channels & RED ? table : NULL;
gTable[1] = channels & GREEN ? table : NULL;
gTable[2] = channels & BLUE ? table : NULL;
writePnmHeader(stdout, &in_pnm);
return pam_transform(stdin, stdout, &in_pnm, gTable);
}
static int
pam_transform(FILE *in_fp, FILE *out_fp,
const struct pnm *in_pnm, table_t **tables) {
int i, c, row, col;
int nbytes = in_pnm->maxval == 65535?2:1;
unsigned char *buf = malloc(in_pnm->width * nbytes * 3);
for (c = 0; c < 3; c++) {
if (tables[c] && tables[c]->n < 1 << (nbytes * 8)) {
fprintf(stderr, "table %d too small (%d)\n", c, tables[c]->n);
return 1;
}
}
for (row = 0; row < in_pnm->height; row++) {
fread(buf, in_pnm->width, nbytes * 3, in_fp);
for (i = 0; i < in_pnm->width; i++) {
for (c = 0; c < 3; c++) {
if (tables[c]) {
int val = buf[(i * 3 + c) * nbytes];
if (nbytes == 2) {
val = (val << 8) | buf[(i * 3 + c) * nbytes + 1];
}
val = tables[c]->value[val];
if (nbytes == 1) {
buf[i * 3 + c] = (unsigned char) val;
} else if (nbytes == 2) {
buf[(i * 3 + c) * 2] = (unsigned char) (val >> 8);
buf[(i * 3 + c) * 2 + 1] = (unsigned char) val;
}
}
}
}
fwrite(buf, in_pnm->width, nbytes * 3, out_fp);
}
free(buf);
return 0;
}
#define MAX_CTRL 256
static table_t*
buildCurve(const char *ctrl_points, int resolution, int maxval) {
table_t *table;
char *pstr, *buf = strdup(ctrl_points);
int i, n = 0;
double X[MAX_CTRL], Y[MAX_CTRL];
gsl_interp_accel *acc;
gsl_spline *spline;
while (pstr = strsep(&buf, ",")) {
if (n >= MAX_CTRL) {
fprintf(stderr, "maximum number of control points (%d) reached.\n",
MAX_CTRL);
break;
}
if (sscanf(pstr, "%lf:%lf", &X[n], &Y[n]) != 2 ||
X[n] < 0.0 || X[n] > 1.0 || Y[n] < 0.0 || Y[n] > 1.0) {
fprintf(stderr, "could not parse control point %s.\n", pstr);
free(buf);
return NULL;
}
n++;
}
free(buf);
if (n < 3) {
fprintf(stderr, "not enough control points specified.\n");
return NULL;
}
table = (table_t*) malloc(sizeof(table_t) + resolution * sizeof(short));
table->n = resolution;
acc = gsl_interp_accel_alloc();
spline = gsl_spline_alloc(gsl_interp_cspline, n);
gsl_spline_init (spline, X, Y, n);
for (i = 0; i < resolution; i++) {
double _x = (double) i / (resolution - 1);
double _y = gsl_spline_eval(spline, _x, acc);
double val = _y * maxval + 0.5;
if (val > maxval) val = (double) maxval;
if (val < 0) val = 0;
table->value[i] = (unsigned short) floor(val);
}
gsl_spline_free(spline);
gsl_interp_accel_free(acc);
return table;
}
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