1 files changed, 136 insertions, 0 deletions
diff --git a/xicc/cv.c b/xicc/cv.c
new file mode 100644
index 0000000..5271bc4
--- /dev/null
+++ b/xicc/cv.c
@@ -0,0 +1,136 @@
+
+/**********************************************************/
+/* Investigate Graphics GEMS transfer curve function parameters */
+/**********************************************************/
+
+/* Author: Graeme Gill
+ * Date:   2003/12/1
+ *
+ * Copyright 2003 Graeme W. Gill
+ *
+ * This material is licenced under the GNU AFFERO GENERAL PUBLIC LICENSE Version 3 :-
+ * see the License.txt file for licencing details.
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <math.h>
+#include <numlib.h>
+#include "plot.h"
+
+void usage(void);
+
+#define XRES 100		/* Plot resolution */
+
+/* Per transfer function */
+static double tfunc(
+double *v,			/* Pointer to first parameter */
+int    luord,		/* Curve order n..MPP_MXTCORD */
+double vv			/* Source of value */
+) {
+	double g;
+	int ord;
+
+	if (vv < 0.0)
+		vv = 0.0;
+	else if (vv > 1.0)
+		vv = 1.0;
+
+	/* Process all the shaper orders from high to low. */
+	/* [These shapers were inspired by a Graphics Gem idea */
+	/* (Gems IV, VI.3, "Fast Alternatives to Perlin's Bias and */
+	/*  Gain Functions, pp 401). */
+	/*  They have the nice properties that they are smooth, and */
+	/*  can't be non-monotonic. The control parameter has been */
+	/*  altered to have a range from -oo to +oo rather than 0.0 to 1.0 */
+	/*  so that the search space is less non-linear. ] */
+	for (ord = luord-1; ord >= 0; ord--) {
+		int nsec;			/* Number of sections */
+		double sec;			/* Section */
+
+		g = v[ord];			/* Parameter */
+
+//		nsec = 1 << ord;	/* Double sections for each order */
+		nsec = ord + 1;		/* Sections for each order */
+
+		vv *= (double)nsec;
+
+		sec = floor(vv);
+		if (((int)sec) & 1)
+			g = -g;				/* Alternate action in each section */
+		vv -= sec;
+		if (g >= 0.0) {
+			vv = vv/(g - g * vv + 1.0);
+		} else {
+			vv = (vv - g * vv)/(1.0 - g * vv);
+		}
+		vv += sec;
+		vv /= (double)nsec;
+	}
+
+	return vv;
+}
+
+
+#define MAX_PARM 10
+
+int
+main(int argc, char *argv[]) {
+	int fa,nfa;				/* argument we're looking at */
+	int np = 0;			/* Current number of input parameters */
+	double params[MAX_PARM] =  { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 };
+	int i;
+	double x;
+	double xx[XRES];
+	double y1[XRES];
+
+	error_program = "cv";
+
+	/* Process the arguments */
+	for(fa = 1;fa < argc;fa++) {
+		nfa = fa;					/* skip to nfa if next argument is used */
+		if (np >= MAX_PARM)
+			break;
+
+		params[np++] = atof(argv[fa]);
+	}
+
+	if (np == 0)
+		np = 1;
+
+	printf("There are %d parameters:\n",np); fflush(stdout);
+	for (i = 0; i < np; i++) {
+		printf("Paramter %d = %f\n",i, params[i]); fflush(stdout);
+	}
+
+	/* Display the result */
+	for (i = 0; i < XRES; i++) {
+		x = i/(double)(XRES-1);
+
+		xx[i] = x;
+		y1[i] = tfunc(params, np, x);
+
+		if (y1[i] < -0.2)
+			y1[i] = -0.2;
+		else if (y1[i] > 1.2)
+			y1[i] = 1.2;
+	}
+	do_plot(xx,y1,NULL,NULL,XRES);
+
+	return 0;
+}
+
+/******************************************************************/
+/* Error/debug output routines */
+/******************************************************************/
+
+void
+usage(void) {
+	puts("usage: cv param0 [param1] [param2] ... ");
+	exit(1);
+}
+
+
+
+
+