From: Grazvydas Ignotas <notasas@gmail.com>
Date: Tue, 9 Oct 2012 22:49:51 +0000 (+0300)
Subject: op_gammatable: black level support
X-Git-Tag: sz_152^0
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=c1506509e34b1b8c7c4b646195fc9827c01c5797;p=pandora-misc.git

op_gammatable: black level support
---

diff --git a/op_gammatable.c b/op_gammatable.c
index dd321ed..690a689 100644
--- a/op_gammatable.c
+++ b/op_gammatable.c
@@ -34,7 +34,8 @@
 static void usage(const char *argv0)
 {
 	fprintf(stderr, "usage:\n");
-	fprintf(stderr, "%s [-n] {<gamma> | <gamma_r> <gamma_g> <gamma_b>}\n",
+	fprintf(stderr, "%s [-n] [-b <black_level>] "
+			"{<gamma> | <gamma_r> <gamma_g> <gamma_b>}\n",
 		argv0);
 	exit(1);
 }
@@ -43,6 +44,7 @@ int main(int argc, char *argv[])
 {
 	unsigned int v, r, g, b;
 	float gamma[3] = { 0.f, };
+	float base = 0.f, scale;
 	int negative = 0, ptod = 0, half = 0;
 	int i, arg = 1;
 
@@ -53,6 +55,11 @@ int main(int argc, char *argv[])
 			usage(argv[0]);
 		else if (strcmp(argv[arg], "-n") == 0)
 			negative = 1;
+		else if (strcmp(argv[arg], "-b") == 0) {
+			arg++;
+			if (arg < argc)
+				base = atof(argv[arg]);
+		}
 		else if (strcmp(argv[arg], "-ptod") == 0)
 			ptod = 1;
 		else if (strcmp(argv[arg], "-half") == 0)
@@ -79,11 +86,18 @@ int main(int argc, char *argv[])
 		usage(argv[0]);
 	}
 
+	if (base < 0.f || base > 255.f) {
+		fprintf(stderr, "invalid black level: %.3f\n", base);
+		usage(argv[0]);
+	}
+	scale = 255.f - base;
+	base += 0.5f; // rounding
+
 	for (i = 0; i < 256; i++) {
 		// based on http://www.teamten.com/lawrence/graphics/gamma/
-		r = (unsigned int) (255.f * powf((float)i / 255.f, 1.f / gamma[0]) + 0.5f);
-		g = (unsigned int) (255.f * powf((float)i / 255.f, 1.f / gamma[1]) + 0.5f);
-		b = (unsigned int) (255.f * powf((float)i / 255.f, 1.f / gamma[2]) + 0.5f);
+		r = (unsigned int) (base + scale * powf((float)i / 255.f, 1.f / gamma[0]));
+		g = (unsigned int) (base + scale * powf((float)i / 255.f, 1.f / gamma[1]));
+		b = (unsigned int) (base + scale * powf((float)i / 255.f, 1.f / gamma[2]));
 
 		v = (r << 16) | (g << 8) | b;
 		if (negative)