From 8b4603fa21b817a89f46d136a5516d441c4c86ff Mon Sep 17 00:00:00 2001
From: tth <sigfood@dinorama.fr>
Date: Tue, 8 Sep 2020 23:39:23 +0200
Subject: [PATCH] adding HSV->RGB functions, expect garbage

---
 funcs/hsv.c | 50 +++++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 49 insertions(+), 1 deletion(-)

diff --git a/funcs/hsv.c b/funcs/hsv.c
index ba70b0b..5eb8ae9 100644
--- a/funcs/hsv.c
+++ b/funcs/hsv.c
@@ -27,7 +27,11 @@ return (fabsf(a-b)<0.00000000000001);		// UGLY HACK ???
 }
 /* --------------------------------------------------------------------- */
 /*
- *		WARNING : ALL THIS CODE IS SHIT
+ *		WARNING : ALL THIS CODE IS STRANGE
+ *
+
+www.tutorialspoint.com/c-program-to-change-rgb-color-model-to-hsv-color-model
+
  */
 int fimg_rgb2hsv(float rgb[3], float hsv[3], float scale)
 {
@@ -62,6 +66,50 @@ fprintf(stderr, "cmin/cmax   %f   %f\n", cmin, cmax);
 
 return 0;
 }
+/* --------------------------------------------------------------------- */
+int fimg_hsv2rgb(float hsv[3], float rgb[3], float scale)
+{
+float		hh, ff, p, q, t;
+long		i;
+
+if(hsv[1] <= 0.0) {       // < is bogus, just shuts up warnings
+        rgb[0] = rgb[1] = rgb[2] = hsv[2];
+        return 0;
+	}
+
+    hh = hsv[0];
+    if(hh >= 360.0) hh = 0.0;
+    hh /= 60.0;
+    i = (long)hh;
+    ff = hh - i;
+    p = hsv[2] * (1.0 -  hsv[1]);
+    q = hsv[2] * (1.0 - (hsv[1] * ff));
+    t = hsv[2] * (1.0 - (hsv[1] * (1.0 - ff)));
+
+switch(i) {
+    case 0:
+	rgb[0] = hsv[2];	rgb[1] = t;		rgb[2] = p;
+	break;
+    case 1:
+	rgb[0] = q;		rgb[1] = hsv[2];	rgb[2] = p;
+	break;
+    case 2:
+	rgb[0] = p;		rgb[1] = hsv[2];	rgb[2] = t;
+	break;
+    case 3:
+	rgb[0] = p;		rgb[1] = q;		rgb[2] = hsv[2];
+	break;
+    case 4:
+	rgb[0] = t;		rgb[1] = p;		rgb[2] = hsv[2];
+	break;
+    case 5:
+    default:
+	rgb[0] = hsv[2];	rgb[1] = p; 		rgb[2] = q;
+        break;
+    }
+return 0;
+}
+
 /* --------------------------------------------------------------------- */
 int fimg_essai_hsv(char *fname)
 {