From 950d6181e32222c659df5720752dc43f0e92b8b6 Mon Sep 17 00:00:00 2001
From: scuri <scuri>
Date: Tue, 18 Nov 2008 13:15:46 +0000
Subject: *** empty log message ***
---
html/en/history.html | 8 ++++
include/im_colorhsi.h | 7 +--
src/im.def | 1 -
src/im_colorhsi.cpp | 120 +++++++++++++++++++++++++++++---------------------
4 files changed, 80 insertions(+), 56 deletions(-)
diff --git a/html/en/history.html b/html/en/history.html
index 446d9cc..fe1979b 100644
--- a/html/en/history.html
+++ b/html/en/history.html
@@ -11,6 +11,14 @@
<body>
<h1>History of Changes</h1>
+<h3 dir="ltr">CVS (18/Nov/2008)</h3>
+<ul>
+ <li><span style="color: #008000">Changed:</span> function <strong>
+ imColorHSI_Smax</strong> removed from public, now it is used only
+ internally. HSI space now uses S already normalized between 0-Smax.</li>
+ <li><span style="color: #FF0000">Fixed:</span> <strong>imColorHSI2RGB</strong>
+ conversion.</li>
+</ul>
<h3 dir="ltr">Version 3.4 (14/Oct/2008)</h3>
<ul>
<li><span style="color: #0000FF">New:</span> imlua_avi, imlua_wmv and imlua_jp2 libraries so the
diff --git a/include/im_colorhsi.h b/include/im_colorhsi.h
index effb62a..9749002 100644
--- a/include/im_colorhsi.h
+++ b/include/im_colorhsi.h
@@ -19,20 +19,15 @@ extern "C" {
* \par
* "I" is defined along the cube diagonal. It ranges from 0 (black) to 1 (white). \n
* HS are the polar coordinates of a plane normal to "I". \n
- * "S" is the normal distance from the diagonal of the RGB cube. It ranges from 0 to Smax. \n
+ * "S" is the normal distance from the diagonal of the RGB cube. It ranges from 0 to 1. \n
* "H" is the angle starting from the red vector, given in degrees.
* \par
* This is not a new color space, this is exactly the same gammut as RGB. \n
- * Since it is still a cube, Smax depends on H.
* \par
* See \ref im_colorhsi.h
* \ingroup color */
-/** Returns the maximum S for H (here in radians) and I.
- * \ingroup hsi */
-float imColorHSI_Smax(float h, double cosh, double sinh, float i);
-
/** Returns I where S is maximum given H (here in radians).
* \ingroup hsi */
float imColorHSI_ImaxS(float h, double cosh, double sinh);
diff --git a/src/im.def b/src/im.def
index 1a39bcf..abd5ec4 100644
--- a/src/im.def
+++ b/src/im.def
@@ -166,7 +166,6 @@ EXPORTS
imBinFileSeekOffset
imBinFileSeekTo
imColorHSI_ImaxS
- imColorHSI_Smax
imColorHSI2RGB
imColorHSI2RGBbyte
imColorRGB2HSI
diff --git a/src/im_colorhsi.cpp b/src/im_colorhsi.cpp
index 3852527..953bb2c 100644
--- a/src/im_colorhsi.cpp
+++ b/src/im_colorhsi.cpp
@@ -2,7 +2,7 @@
* \brief HSI Color Manipulation
*
* See Copyright Notice in im_lib.h
- * $Id: im_colorhsi.cpp,v 1.1 2008/10/17 06:10:16 scuri Exp $
+ * $Id: im_colorhsi.cpp,v 1.2 2008/11/18 13:15:46 scuri Exp $
*/
@@ -18,12 +18,25 @@ static const float rad240 = 4.1887902f;
static const float rad300 = 5.2359877f;
static const float rad360 = 6.2831853f;
static const float sqrt3 = 1.7320508f;
+static const float rad2deg = 57.2957795131f;
+
+
+static double iColorNormHue(double H)
+{
+ while (H < 0.0)
+ H += rad360;
+
+ if (H > rad360)
+ H = fmod(H, (double)rad360);
+
+ return H;
+}
/**********************************/
/* HSI MAX S */
/**********************************/
-static void iSmax01(float h, float hr, float hb, float hg, float *h0, float *h1)
+static void iColorSmax01(float h, float hr, float hb, float hg, float *h0, float *h1)
{
if (h < rad60)
{
@@ -57,22 +70,24 @@ static void iSmax01(float h, float hr, float hb, float hg, float *h0, float *h1)
}
}
-float imColorHSI_Smax(float h, double cosh, double sinh, float i)
+static float iColorHSI_Smax(float h, double cosH, double sinH, float i)
{
float hr, hb, hg, imax, h0, h1;
+ /* i here is normalized between 0-1 */
+
if (i == 0 || i == 1)
return 0.0f;
- if (i == 1.0f/3.0f || i == 2.0f/3.0f)
- return 1.0f;
+ /* Making r=0, g=0, b=0, r=1, g=1 or b=1 in the parametric equations and
+ writting s in function of H and I. */
- hr = (float)(cosh / 1.5);
- hg = (float)((-cosh + sinh*sqrt3)/ 3.0);
- hb = (float)((-cosh - sinh*sqrt3)/ 3.0);
+ hr = (float)(cosH / 1.5);
+ hg = (float)((-cosH + sinH*sqrt3)/ 3.0);
+ hb = (float)((-cosH - sinH*sqrt3)/ 3.0);
/* at bottom */
- if (i < 1.0f/3.0f)
+ if (i <= 1.0f/3.0f)
{
/* face B=0 */
if (h < rad120)
@@ -87,7 +102,7 @@ float imColorHSI_Smax(float h, double cosh, double sinh, float i)
}
/* at top */
- if (i > 2.0f/3.0f)
+ if (i >= 2.0f/3.0f)
{
/* face R=1 */
if (h < rad60 || h > rad300)
@@ -103,7 +118,7 @@ float imColorHSI_Smax(float h, double cosh, double sinh, float i)
/* in the middle */
- iSmax01(h, hr, hb, hg, &h0, &h1);
+ iColorSmax01(h, hr, hb, hg, &h0, &h1);
if (h == 0 || h == rad120 || h == rad240)
imax = 1.0f/3.0f;
@@ -118,7 +133,7 @@ float imColorHSI_Smax(float h, double cosh, double sinh, float i)
return (1-i)/h1;
}
-float imColorHSI_ImaxS(float h, double cosh, double sinh)
+float imColorHSI_ImaxS(float h, double cosH, double sinH)
{
float i, h0, h1;
float hr, hb, hg;
@@ -129,11 +144,11 @@ float imColorHSI_ImaxS(float h, double cosh, double sinh)
if (h == rad60 || h == rad180 || h == rad300)
return 2.0f/3.0f;
- hr = (float)(cosh / 1.5f);
- hg = (float)((-cosh + sinh*sqrt3)/ 3.0);
- hb = (float)((-cosh - sinh*sqrt3)/ 3.0);
+ hr = (float)(cosH / 1.5f);
+ hg = (float)((-cosH + sinH*sqrt3)/ 3.0);
+ hb = (float)((-cosH - sinH*sqrt3)/ 3.0);
- iSmax01(h, hr, hb, hg, &h0, &h1);
+ iColorSmax01(h, hr, hb, hg, &h0, &h1);
i = h0 / (h0 - h1);
@@ -149,19 +164,31 @@ void imColorRGB2HSI(float r, float g, float b, float *h, float *s, float *i)
float v, u;
double H;
+ /* Parametric equations */
v = r - (g + b)/2;
u = (g - b) * (sqrt3/2);
- *i = (r + g + b)/3;
- *s = (float)sqrt(v*v + u*u);
+ *i = (r + g + b)/3; /* already normalized to 0-1 */
+ *s = (float)sqrt(v*v + u*u); /* s is between 0-1, it is linear in the cube and it is in u,v space. */
if (*s == 0)
*h = 360.0f; /* by definition */
else
{
H = atan2(u, v);
- if (H < 0.0f) H += rad360;
- *h = (float)(H * 57.2957795131);
+ H = iColorNormHue(H);
+ *h = (float)(H * rad2deg);
+
+ /* must scale S from 0-Smax to 0-1 */
+ float Smax = iColorHSI_Smax((float)H, cos(H), sin(H), *i);
+ if (Smax == 0.0f)
+ *s = 0.0f;
+ else
+ {
+ if (*s > Smax) /* because of round problems when calculating s and Smax */
+ *s = Smax;
+ *s /= Smax;
+ }
}
}
@@ -180,15 +207,13 @@ void imColorRGB2HSIbyte(unsigned char r, unsigned char g, unsigned char b, float
void imColorHSI2RGB(float h, float s, float i, float *r, float *g, float *b)
{
- static int first = 1;
- static double _sqrt3;
- double cosh, sinh, H, v, u;
+ double cosH, sinH, H, v, u;
- if (first)
- {
- _sqrt3 = sqrt(3.0);
- first = 0;
- }
+ if (i < 0) i = 0;
+ else if (i > 1) i = 1;
+
+ if (s < 0) s = 0;
+ else if (s > 1) s = 1;
if (s == 0.0f || i == 1.0f || i == 0.0f || (int)h == 360)
{
@@ -198,33 +223,30 @@ void imColorHSI2RGB(float h, float s, float i, float *r, float *g, float *b)
return;
}
- if (i < 0) i = 0;
- if (i > 1) i = 1;
-
- if (h > 360) h = (float)fmod(h, 360);
- if (h < 0.0f) h += 360;
-
- H = h / 57.2957795131;
+ H = h/rad2deg;
+ H = iColorNormHue(H);
- cosh = cos(H);
- sinh = sin(H);
+ cosH = cos(H);
+ sinH = sin(H);
- {
- float smax = imColorHSI_Smax((float)H, cosh, sinh, i);
- if (s < 0) s = 0;
- if (s > smax) s = smax;
- }
+ /* must scale S from 0-1 to 0-Smax */
+ float Smax = iColorHSI_Smax((float)H, cosH, sinH, i);
+ s *= Smax;
+ if (s > 1.0f) /* because of round problems when calculating s and Smax */
+ s = 1.0f;
- v = s * cosh;
- u = s * sinh * _sqrt3;
+ v = s * cosH;
+ u = s * sinH;
+ /* Inverse of the Parametric equations, using i normalized to 0-1 */
*r = (float)(i + v/1.5);
- *g = (float)(i - (v - u)/3.0);
- *b = (float)(i - (v + u)/3.0);
+ *g = (float)(i - (v - u*sqrt3)/3.0);
+ *b = (float)(i - (v + u*sqrt3)/3.0);
- if (*r < 0) *r = -*r;
- if (*g < 0) *g = -*g;
- if (*b < 0) *b = -*b;
+ /* fix round errors */
+ if (*r < 0) *r = 0;
+ if (*g < 0) *g = 0;
+ if (*b < 0) *b = 0;
if (*r > 1) *r = 1.0f;
if (*g > 1) *g = 1.0f;
--
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