Changes to rgb2hsv_approximate. Improvements, I think, even.

1 files changed, 87 insertions, 32 deletions

diff --git a/hsv2rgb.cpp b/hsv2rgb.cpp
index 17c20c4c..8ba642d4 100644
--- a/hsv2rgb.cpp
+++ b/hsv2rgb.cpp
@@ -450,7 +450,6 @@ void hsv2rgb_rainbow( const CHSV& hsv, CRGB& rgb)
 
     // Now scale everything down if we're at value < 255.
     if( val != 255 ) {
-
         val = scale8_video_LEAVING_R1_DIRTY( val, val);
         nscale8x3_video( r, g, b, val);
     }
@@ -498,41 +497,72 @@ CHSV rgb2hsv_approximate( const CRGB& rgb)
     uint8_t g = rgb.g;
     uint8_t b = rgb.b;
     uint8_t h, s, v;
-
+    
     // find desaturation
     uint8_t desat = 255;
     if( r < desat) desat = r;
     if( g < desat) desat = g;
     if( b < desat) desat = b;
-
+    
     // remove saturation from all channels
     r -= desat;
     g -= desat;
     b -= desat;
-
+    
+    //Serial.print("desat="); Serial.print(desat); Serial.println("");
+    
+    //uint8_t orig_desat = sqrt16( desat * 256);
+    //Serial.print("orig_desat="); Serial.print(orig_desat); Serial.println("");
+    
+    // saturation is opposite of desaturation
+    s = 255 - desat;
+    //Serial.print("s.1="); Serial.print(s); Serial.println("");
+    
+    if( s != 255 ) {
+        // undo 'dimming' of saturation
+        s = 255 - sqrt16( (255-s) * 256);
+    }
+    // without lib8tion: float ... ew ... sqrt... double ew, or rather, ew ^ 0.5
+    // if( s != 255 ) s = (255 - (256.0 * sqrt( (float)(255-s) / 256.0)));
+    //Serial.print("s.2="); Serial.print(s); Serial.println("");
+    
+    
     // at least one channel is now zero
-
     // if all three channels are zero, we had a
     // shade of gray.
-
-    uint16_t total = r + g + b;
-
-    if( total == 0) {
+    if( (r + g + b) == 0) {
         // we pick hue zero for no special reason
-        return CHSV( 0, 0, desat);
+        return CHSV( 0, 0, 255 - s);
     }
-
-    // since this wasn't a pure shade of gray,
-    // the interesting question is what hue is it
-
-    // scale all channels up to a total of 255
-    if( total != 255) {
+    
+    // scale all channels up to compensate for desaturation
+    if( s < 255) {
+        if( s == 0) s = 1;
+        uint32_t scaleup = 65535 / (s);
+        r = ((uint32_t)(r) * scaleup) / 256;
+        g = ((uint32_t)(g) * scaleup) / 256;
+        b = ((uint32_t)(b) * scaleup) / 256;
+    }
+    //Serial.print("r.2="); Serial.print(r); Serial.println("");
+    //Serial.print("g.2="); Serial.print(g); Serial.println("");
+    //Serial.print("b.2="); Serial.print(b); Serial.println("");
+    
+    uint16_t total = r + g + b;
+    
+    //Serial.print("total="); Serial.print(total); Serial.println("");
+    
+    // scale all channels up to compensate for low values
+    if( total < 255) {
+        if( total == 0) total = 1;
         uint32_t scaleup = 65535 / (total);
         r = ((uint32_t)(r) * scaleup) / 256;
         g = ((uint32_t)(g) * scaleup) / 256;
         b = ((uint32_t)(b) * scaleup) / 256;
     }
-
+    //Serial.print("r.3="); Serial.print(r); Serial.println("");
+    //Serial.print("g.3="); Serial.print(g); Serial.println("");
+    //Serial.print("b.3="); Serial.print(b); Serial.println("");
+    
     if( total > 255 ) {
         v = 255;
     } else {
@@ -541,35 +571,44 @@ CHSV rgb2hsv_approximate( const CRGB& rgb)
         if( v != 255) v = sqrt16( v * 256);
         // without lib8tion: float ... ew ... sqrt... double ew, or rather, ew ^ 0.5
         // if( v != 255) v = (256.0 * sqrt( (float)(v) / 256.0));
-
+        
     }
-
-    // saturation is opposite of desaturation
-    s = 255 - desat;
+    
+    //Serial.print("v="); Serial.print(v); Serial.println("");
+    
+    
+#if 0
+    
+    //#else
     if( v != 255) {
         // this part could probably use refinement/rethinking,
         // (but it doesn't overflow & wrap anymore)
         uint16_t s16;
         s16 = (s * 256);
         s16 /= v;
+        //Serial.print("s16="); Serial.print(s16); Serial.println("");
         if( s16 < 256) {
             s = s16;
         } else {
             s = 255; // clamp to prevent overflow
         }
     }
-
-    // undo 'dimming' of saturation
-    if( s != 255 ) s = 255 - sqrt16( (255-s) * 256);
-    // without lib8tion: float ... ew ... sqrt... double ew, or rather, ew ^ 0.5
-    // if( s != 255 ) s = (255 - (256.0 * sqrt( (float)(255-s) / 256.0)));
-
+#endif
+    
+    //Serial.print("s.3="); Serial.print(s); Serial.println("");
+    
+    
+    // since this wasn't a pure shade of gray,
+    // the interesting question is what hue is it
+    
+    
+    
     // start with which channel is highest
     // (ties don't matter)
     uint8_t highest = r;
     if( g > highest) highest = g;
     if( b > highest) highest = b;
-
+    
     if( highest == r ) {
         // Red is highest.
         // Hue could be Purple/Pink-Red,Red-Orange,Orange-Yellow
@@ -586,14 +625,22 @@ CHSV rgb2hsv_approximate( const CRGB& rgb)
             h = HUE_ORANGE;
             h += scale8( qsub8((g - 85) + (171 - r), 4), FIXFRAC8(32,85)); //221
         }
-
+        
     } else if ( highest == g) {
         // Green is highest
         // Hue could be Yellow-Green, Green-Aqua
         if( b == 0) {
             // if Blue is zero, we're in Yellow-Green
+            //   G = 171..255
+            //   R = 171..  0
             h = HUE_YELLOW;
-            h += scale8( qadd8( qadd8((g - 128), (128 - r)), 4), FIXFRAC8(32,255)); //
+            uint8_t radj = scale8( qsub8(171,r),   47); //171..0 -> 0..171 -> 0..31
+            uint8_t gadj = scale8( qsub8(g,171),   96); //171..255 -> 0..84 -> 0..31;
+            uint8_t rgadj = radj + gadj;
+            uint8_t hueadv = rgadj / 2;
+            h += hueadv;
+            //h += scale8( qadd8( 4, qadd8((g - 128), (128 - r))),
+            //             FIXFRAC8(32,255)); //
         } else {
             // if Blue is nonzero we're in Green-Aqua
             if( (g-b) > b) {
@@ -604,7 +651,7 @@ CHSV rgb2hsv_approximate( const CRGB& rgb)
                 h += scale8( qsub8(b, 85), FIXFRAC8(8,42));
             }
         }
-
+        
     } else /* highest == b */ {
         // Blue is highest
         // Hue could be Aqua/Blue-Blue, Blue-Purple, Purple-Pink
@@ -622,9 +669,17 @@ CHSV rgb2hsv_approximate( const CRGB& rgb)
             h += scale8( qsub8(r, 85), FIXFRAC8(32,85));
         }
     }
-
+    
     h += 1;
     return CHSV( h, s, v);
 }
 
+// Examples that need work:
+//   0,192,192
+//   192,64,64
+//   224,32,32
+//   252,0,126
+//   252,252,0
+//   252,252,126
+
 FASTLED_NAMESPACE_END