Added HSV2RGB and RGB2HSV functions for higher accuracy conversions

- also added a struct to handle HSV with 16bit hue better (including some conversions, can be extended easily)
- the functions are optimized for speed and flash use. They are faster and more accurate than what fastled offers (and use much less flash).
- replaced colorHStoRGB() with a call to the new hsv2rgb() function, saving even more flash (new function is untested!)
- the 16bit hue calculations result in an almost perfect conversion from RGB to HSV and back, the maximum error was 1/255 in the cases I tested.

wled00/colors.cpp

@@ -239,26 +239,64 @@ CRGBPalette16 generateRandomPalette()  //generate fully random palette
                        CHSV(random8(), random8(160, 255), random8(128, 255)));
 }
 
-void colorHStoRGB(uint16_t hue, byte sat, byte* rgb) //hue, sat to rgb
+void hsv2rgb(const CHSV32& hsv, uint32_t& rgb) // convert HSV (16bit hue) to RGB (32bit with white = 0)
 {
-  float h = ((float)hue)/10922.5f; // hue*6/65535
+  unsigned int remainder, region, p, q, t;
-  float s = ((float)sat)/255.0f;
+  unsigned int h = hsv.h;
-  int   i = int(h);
+  unsigned int s = hsv.s;
-  float f = h - i;
+  unsigned int v = hsv.v;
-  int   p = int(255.0f * (1.0f-s));
+  if (s == 0) {
-  int   q = int(255.0f * (1.0f-s*f));
+      rgb = v << 16 | v << 8 | v;
-  int   t = int(255.0f * (1.0f-s*(1.0f-f)));
+      return;
-  p = constrain(p, 0, 255);
-  q = constrain(q, 0, 255);
-  t = constrain(t, 0, 255);
-  switch (i%6) {
-    case 0: rgb[0]=255,rgb[1]=t,  rgb[2]=p;  break;
-    case 1: rgb[0]=q,  rgb[1]=255,rgb[2]=p;  break;
-    case 2: rgb[0]=p,  rgb[1]=255,rgb[2]=t;  break;
-    case 3: rgb[0]=p,  rgb[1]=q,  rgb[2]=255;break;
-    case 4: rgb[0]=t,  rgb[1]=p,  rgb[2]=255;break;
-    case 5: rgb[0]=255,rgb[1]=p,  rgb[2]=q;  break;
   }
+  region = h / 10923;  // 65536 / 6 = 10923
+  remainder = (h - (region * 10923)) * 6;
+  p = (v * (256 - s)) >> 8;
+  q = (v * (255 - ((s * remainder) >> 16))) >> 8;
+  t = (v * (255 - ((s * (65535 - remainder)) >> 16))) >> 8;
+  switch (region) {
+    case 0:
+      rgb = v << 16 | t << 8 | p; break;
+    case 1:
+      rgb = q << 16 | v << 8 | p; break;
+    case 2:
+      rgb = p << 16 | v << 8 | t; break;
+    case 3:
+      rgb = p << 16 | q << 8 | v; break;
+    case 4:
+      rgb = t << 16 | p << 8 | v; break;
+    default:
+      rgb = v << 16 | p << 8 | q; break;
+  }
+}
+
+void rgb2hsv(const uint32_t rgb, CHSV32& hsv) // convert RGB to HSV (16bit hue), much more accurate and faster than fastled version
+{
+    hsv.raw = 0;
+    int32_t r = (rgb>>16)&0xFF;
+    int32_t g = (rgb>>8)&0xFF;
+    int32_t b = rgb&0xFF;
+    int32_t minval, maxval, delta;
+    minval = min(r, g);
+    minval = min(minval, b);
+    maxval = max(r, g);
+    maxval = max(maxval, b);
+    if (maxval == 0)  return; // black
+    hsv.v = maxval;
+    delta = maxval - minval;
+    hsv.s = (255 * delta) / maxval;
+    if (hsv.s == 0)  return; // gray value
+    if (maxval == r) hsv.h = (10923 * (g - b)) / delta;
+    else if (maxval == g)  hsv.h = 21845 + (10923 * (b - r)) / delta;
+    else hsv.h = 43690 + (10923 * (r - g)) / delta;
+}
+
+void colorHStoRGB(uint16_t hue, byte sat, byte* rgb) { //hue, sat to rgb
+  uint32_t crgb;
+  hsv2rgb(CHSV32(hue, sat, 255), crgb);
+  rgb[0] = byte((crgb) >> 16);
+  rgb[1] = byte((crgb) >> 8);
+  rgb[2] = byte(crgb);
 }
 
 //get RGB values from color temperature in K (https://tannerhelland.com/2012/09/18/convert-temperature-rgb-algorithm-code.html)

wled00/fcn_declare.h

@@ -67,6 +67,30 @@ typedef struct WiFiConfig {
 
 //colors.cpp
 #define ColorFromPalette ColorFromPaletteWLED // override fastled version
+
+struct CHSV32 { // 32bit HSV color with 16bit hue for more accurate conversions
+  union {
+    struct {
+        uint16_t h;  // hue
+        uint8_t s;   // saturation
+        uint8_t v;   // value
+    };
+    uint32_t raw;    // 32bit access
+  };
+  inline CHSV32() __attribute__((always_inline)) = default; // default constructor
+
+    /// Allow construction from hue, saturation, and value
+    /// @param ih input hue
+    /// @param is input saturation
+    /// @param iv input value
+  inline CHSV32(uint16_t ih, uint8_t is, uint8_t iv) __attribute__((always_inline)) // constructor from 16bit h, s, v
+        : h(ih), s(is), v(iv) {}
+  inline CHSV32(uint8_t ih, uint8_t is, uint8_t iv) __attribute__((always_inline)) // constructor from 8bit h, s, v
+        : h((uint16_t)ih << 8), s(is), v(iv) {}
+  inline CHSV32(const CHSV& chsv) __attribute__((always_inline))  // constructor from CHSV
+    : h((uint16_t)chsv.h << 8), s(chsv.s), v(chsv.v) {}
+  inline operator CHSV() const { return CHSV((uint8_t)(h >> 8), s, v); } // typecast to CHSV
+};
 // similar to NeoPixelBus NeoGammaTableMethod but allows dynamic changes (superseded by NPB::NeoGammaDynamicTableMethod)
 class NeoGammaWLEDMethod {
   public:
@@ -86,7 +110,10 @@ class NeoGammaWLEDMethod {
 CRGBPalette16 generateHarmonicRandomPalette(CRGBPalette16 &basepalette);
 CRGBPalette16 generateRandomPalette();
 inline uint32_t colorFromRgbw(byte* rgbw) { return uint32_t((byte(rgbw[3]) << 24) | (byte(rgbw[0]) << 16) | (byte(rgbw[1]) << 8) | (byte(rgbw[2]))); }
-void colorHStoRGB(uint16_t hue, byte sat, byte* rgb); //hue, sat to rgb
+void hsv2rgb(const CHSV32& hsv, uint32_t& rgb);
+void colorHStoRGB(uint16_t hue, byte sat, byte* rgb);
+void rgb2hsv(const uint32_t rgb, CHSV32& hsv);
+inline CHSV rgb2hsv(const CRGB c) { CHSV32 hsv; rgb2hsv((uint32_t((byte(c.r) << 16) | (byte(c.g) << 8) | (byte(c.b)))), hsv); return CHSV(hsv); } // CRGB to hsv
 void colorKtoRGB(uint16_t kelvin, byte* rgb);
 void colorCTtoRGB(uint16_t mired, byte* rgb); //white spectrum to rgb
 void colorXYtoRGB(float x, float y, byte* rgb); // only defined if huesync disabled TODO

wled00/ir.cpp

@@ -129,7 +129,7 @@ static void changeEffectSpeed(int8_t amount)
   } else { // if Effect == "solid Color", change the hue of the primary color
     Segment& sseg = irApplyToAllSelected ? strip.getFirstSelectedSeg() : strip.getMainSegment();
     CRGB fastled_col = CRGB(sseg.colors[0]);
-    CHSV prim_hsv = rgb2hsv_approximate(fastled_col);
+    CHSV prim_hsv = rgb2hsv(fastled_col);
     int16_t new_val = (int16_t)prim_hsv.h + amount;
     if (new_val > 255) new_val -= 255;  // roll-over if  bigger than 255
     if (new_val < 0) new_val += 255;    // roll-over if smaller than 0
@@ -173,7 +173,7 @@ static void changeEffectIntensity(int8_t amount)
   } else { // if Effect == "solid Color", change the saturation of the primary color
     Segment& sseg = irApplyToAllSelected ? strip.getFirstSelectedSeg() : strip.getMainSegment();
     CRGB fastled_col = CRGB(sseg.colors[0]);
-    CHSV prim_hsv = rgb2hsv_approximate(fastled_col);
+    CHSV prim_hsv = rgb2hsv(fastled_col);
     int16_t new_val = (int16_t) prim_hsv.s + amount;
     prim_hsv.s = (byte)constrain(new_val,0,255);  // constrain to 0-255
     hsv2rgb_rainbow(prim_hsv, fastled_col);