start working on color correction and brightness control

esp8266-house-led-rgb.ino

@@ -78,6 +78,73 @@ uint8_t red = 1;
 uint8_t green = 1;
 uint8_t blue = 1;
 
+// quick fix for gamma correction from Adafruit's Phillip Burgess
+static uint8_t phillip_adafruitGamma8[] = {
+    0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,
+    0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  1,  1,  1,  1,
+    1,  1,  1,  1,  1,  1,  1,  1,  1,  2,  2,  2,  2,  2,  2,  2,
+    2,  3,  3,  3,  3,  3,  3,  3,  4,  4,  4,  4,  4,  5,  5,  5,
+    5,  6,  6,  6,  6,  7,  7,  7,  7,  8,  8,  8,  9,  9,  9, 10,
+   10, 10, 11, 11, 11, 12, 12, 13, 13, 13, 14, 14, 15, 15, 16, 16,
+   17, 17, 18, 18, 19, 19, 20, 20, 21, 21, 22, 22, 23, 24, 24, 25,
+   25, 26, 27, 27, 28, 29, 29, 30, 31, 32, 32, 33, 34, 35, 35, 36,
+   37, 38, 39, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 50,
+   51, 52, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 66, 67, 68,
+   69, 70, 72, 73, 74, 75, 77, 78, 79, 81, 82, 83, 85, 86, 87, 89,
+   90, 92, 93, 95, 96, 98, 99,101,102,104,105,107,109,110,112,114,
+  115,117,119,120,122,124,126,127,129,131,133,135,137,138,140,142,
+  144,146,148,150,152,154,156,158,160,162,164,167,169,171,173,175,
+  177,180,182,184,186,189,191,193,196,198,200,203,205,208,210,213,
+  215,218,220,223,225,228,231,233,236,239,241,244,247,249,252,255 };
+
+// another implementation of gamma correction produced by bg100: f(x) = 1/(1+EXP(((A2/21)-6)*-1))*255
+static uint8_t bg100_sCurveGamma8[] = {
+  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01,
+  0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x02, 0x02, 0x02, 0x02, 0x02, 0x02, 0x02,
+  0x02, 0x02, 0x03, 0x03, 0x03, 0x03, 0x03, 0x03, 0x04, 0x04, 0x04, 0x04, 0x04, 0x05, 0x05, 0x05,
+  0x05, 0x06, 0x06, 0x06, 0x07, 0x07, 0x07, 0x08, 0x08, 0x08, 0x09, 0x09, 0x0A, 0x0A, 0x0B, 0x0B,
+  0x0C, 0x0C, 0x0D, 0x0D, 0x0E, 0x0F, 0x0F, 0x10, 0x11, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17,
+  0x18, 0x19, 0x1A, 0x1B, 0x1C, 0x1D, 0x1F, 0x20, 0x21, 0x23, 0x24, 0x26, 0x27, 0x29, 0x2B, 0x2C,
+  0x2E, 0x30, 0x32, 0x34, 0x36, 0x38, 0x3A, 0x3C, 0x3E, 0x40, 0x43, 0x45, 0x47, 0x4A, 0x4C, 0x4F,
+  0x51, 0x54, 0x57, 0x59, 0x5C, 0x5F, 0x62, 0x64, 0x67, 0x6A, 0x6D, 0x70, 0x73, 0x76, 0x79, 0x7C,
+  0x7F, 0x82, 0x85, 0x88, 0x8B, 0x8E, 0x91, 0x94, 0x97, 0x9A, 0x9C, 0x9F, 0xA2, 0xA5, 0xA7, 0xAA,
+  0xAD, 0xAF, 0xB2, 0xB4, 0xB7, 0xB9, 0xBB, 0xBE, 0xC0, 0xC2, 0xC4, 0xC6, 0xC8, 0xCA, 0xCC, 0xCE,
+  0xD0, 0xD2, 0xD3, 0xD5, 0xD7, 0xD8, 0xDA, 0xDB, 0xDD, 0xDE, 0xDF, 0xE1, 0xE2, 0xE3, 0xE4, 0xE5,
+  0xE6, 0xE7, 0xE8, 0xE9, 0xEA, 0xEB, 0xEC, 0xED, 0xED, 0xEE, 0xEF, 0xEF, 0xF0, 0xF1, 0xF1, 0xF2,
+  0xF2, 0xF3, 0xF3, 0xF4, 0xF4, 0xF5, 0xF5, 0xF6, 0xF6, 0xF6, 0xF7, 0xF7, 0xF7, 0xF8, 0xF8, 0xF8,
+  0xF9, 0xF9, 0xF9, 0xF9, 0xFA, 0xFA, 0xFA, 0xFA, 0xFA, 0xFB, 0xFB, 0xFB, 0xFB, 0xFB, 0xFB, 0xFC,
+  0xFC, 0xFC, 0xFC, 0xFC, 0xFC, 0xFC, 0xFC, 0xFC, 0xFD, 0xFD, 0xFD, 0xFD, 0xFD, 0xFD, 0xFD, 0xFD,
+  0xFD, 0xFD, 0xFD, 0xFD, 0xFD, 0xFD, 0xFD, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFF, 0xFF
+}
+
+/*  Fast-Led typical smd5050 led RGB color correction (0xFFB0F0 red 255, green 176, blue 240)
+ *  measured brightness from typical LED vary by pn junction semiconductor material.
+ *  
+ *  [?] I am not too sure if this is measured by human eye or by device.  Human eyes have thee
+ *      issues that need to be accounted for, one is the non-linear brightness that our nerves send
+ *      to our brains.  Our eyes are more sensitive to green light.  The last problem is not really
+ *      something we can handle in code as it in the realm of psychophysics, Weber–Fechner laws.  The
+ *      Weber–Fechner has to do with the way our brains have a big impact on human perception.
+ *      
+ *  I believe that this color correction has to do with mechanical measurements as they are linear
+ *  and I know that the human eye sensitivities are anything but.  Otherwise this is very crude.
+ */
+static uint8_t redCorrection    = 0xFF;
+static uint8_t greenCorrection  = 0xB0;
+static uint8_t blueCorrection   = 0xF0;
+
+/*  we are going to cheat the brightness by adjusting pwm resolution
+ *   
+ *  in effect this will change the brightness and we will not need to perform any math
+ *  the way this works is that PWM resolution is 10-bit but when we set the duty-cycle
+ *  we only use values [0..255].  By increasing the resoltion past 255 we reduce the
+ *  brightness.  Cool.
+ */
+void adjustBrightness() {
+  analogWriteRange(511);
+}
+
+
 ESP8266WebServer server(80);    // Create a webserver object that listens for HTTP request on port 80
 
 void handleRoot();              // function prototypes for HTTP handlers
@@ -316,4 +383,4 @@ void handleLogin() {                         // If a POST request is made to URI
 
 void handleNotFound(){
   server.send(404, "text/plain", "404: Not found"); // Send HTTP status 404 (Not Found) when there's no handler for the URI in the request
-}
+}