1 files changed, 168 insertions, 0 deletions
diff --git a/src/pnmcurve.c b/src/pnmcurve.c
new file mode 100644
index 0000000..e170f36
--- /dev/null
+++ b/src/pnmcurve.c
@@ -0,0 +1,168 @@
+#include <stdio.h>
+#include <unistd.h>
+#include <string.h>
+#include <math.h>
+
+#include <gsl/gsl_spline.h>
+
+#include "pnm.h"
+
+typedef struct {
+	int n;
+	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);
+
+#define RED 0x1
+#define GREEN 0x2
+#define BLUE 0x4
+
+int
+main(int argc, char **argv) {
+	int c, i;
+	char *curve = NULL;
+	struct pnm in_pnm;
+	int channels = 0;
+	table_t *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 (readPnmHeader(stdin, &in_pnm) != 0) {
+		exit(1);
+	}
+
+	if (in_pnm.maxval == 255) {
+	} else if (in_pnm.maxval == 65535) {
+	} else {
+		fprintf(stderr, "unsupported PNM maxval %d\n", in_pnm.maxval);
+		exit(1);
+	}
+
+	if (curve) {
+		table_t *table;
+
+		if (channels == 0) channels = RED | GREEN | BLUE;
+
+		table = buildCurve(curve, 256);
+	
+		gTable[0] = channels & RED?table:NULL;	
+		gTable[1] = channels & GREEN?table:NULL;	
+		gTable[2] = channels & BLUE?table:NULL;	
+
+	}
+
+	writePnmHeader(stdout, &in_pnm);
+
+	pam_transform(stdin, stdout, &in_pnm, gTable);
+
+	return 0;
+}
+
+static int
+pam_transform(FILE *in_fp, FILE *out_fp,
+	const struct pnm *in_pnm, table_t **tables) {
+	int row, col;
+	int nbytes = in_pnm->maxval == 65535?2:1;
+	char *buf = malloc(in_pnm->width * nbytes * 3);
+
+	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 < in_pnm->depth; c++) {
+				if (tables[c]) {
+					int val = (unsigned char) buf[(i * in_pnm->depth + c) * nbytes];	
+					if (nbytes == 2) {
+						val = (val << 8) |
+							(uchar) buf[(i * in_pnm->depth + c) * nbytes + 1];
+					}
+
+					bud
+
+				}
+			}
+		}
+
+		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) {
+	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);
+
+	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 dval = _y * 65535.0 + .5;
+        if (dval > 65535.) dval = 65535.0;
+        if (dval < 0) dval = 0;
+
+        table->value[i] = (short) floor(dval);
+	}
+
+	gsl_spline_free(spline);
+	gsl_interp_accel_free(acc);
+	
+	return table;
+}