optimize (#6)

- major improvement **BGR()**
- minor improvement **CMYK()**
- extend timing example.
- update readme.md
- update GitHub actions
- update license 2023

CHANGELOG.md

@@ -6,6 +6,15 @@ The format is based on [Keep a Changelog](http://keepachangelog.com/)
 and this project adheres to [Semantic Versioning](http://semver.org/).
 
 
+## [0.1.6] - 2022-11-14
+- major improvement **BGR()**
+- minor improvement **CMYK()**
+- extend timing example.
+- update readme.md
+- update GitHub actions
+- update license 2023
+
+
 ## [0.1.5] - 2022-11-14
 - Add RP2040 support to build-CI.
 - Add CHANGELOG.md
@@ -14,7 +23,6 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 - fix bug in **BGR()**
 - fix unit test BGR-bug
 
-
 ## [0.1.4] - 2021-12-20
 - update library.json
 - update license

Kelvin2RGB.cpp

@@ -1,12 +1,10 @@
 //
 //    FILE: Kelvin2RGB.cpp
 //  AUTHOR: Rob Tillaart
-// VERSION: 0.1.5
+// VERSION: 0.1.6
 //    DATE: 2018-01-31
 // PURPOSE: Arduino library for converting temperature to RGB values
 //     URL: https://github.com/RobTillaart/Kelvin2RGB
-//
-// HISTORY: see changelog.md
 
 
 #include "Kelvin2RGB.h"
@@ -169,11 +167,11 @@ uint32_t Kelvin2RGB::RGB()
 uint16_t Kelvin2RGB::RGB565()
 {
   uint16_t val = 0;
-  val  = uint8_t(_red * 32);
+  val  = uint8_t(_red   * 32);
   val <<= 6;
   val |= uint8_t(_green * 64);
   val <<= 5;
-  val |= uint8_t(_blue * 32);
+  val |= uint8_t(_blue  * 32);
   return val;
 }
 
@@ -183,18 +181,23 @@ uint32_t Kelvin2RGB::CMYK()
   float k = _red;
   if (k < _green) k = _green;
   if (k < _blue) k = _blue;
+
+  float t1 = k;
   k = 1 - k;
-  uint32_t c = 255 * (1 - _red   - k) / (1 - k);
-  uint32_t m = 255 * (1 - _green - k) / (1 - k);
-  uint32_t y = 255 * (1 - _blue  - k) / (1 - k);
+  float t2 = 255.0 / (1 - k);
+
+  uint32_t c = (t1 - _red  ) * t2;
+  uint32_t m = (t1 - _green) * t2;
+  uint32_t y = (t1 - _blue ) * t2;
 
   return (c << 24) + (m << 16) + (y << 8) + (k * 255);
 }
 
 
 uint32_t Kelvin2RGB::BGR()
 {
-  return round(255 * _blue) * 65536UL + round(255 * _green) * 256UL + round(255 * _red);
+  return uint8_t(255 * _blue + 0.5) * 65536UL + uint8_t(255 * _green + 0.5) * 256UL + uint8_t(255 * _red + 0.5);
+  //  return round(255 * 65536UL * _blue) + round(255 * 256UL * _green) + round(255 * _red);
 }
 
 

Kelvin2RGB.h

@@ -2,14 +2,13 @@
 //
 //    FILE: Kelvin2RGB.h
 //  AUTHOR: Rob Tillaart
-// VERSION: 0.1.5
+// VERSION: 0.1.6
 //    DATE: 2018-01-31
 // PURPOSE: Arduino library for converting temperature to RGB values
 //     URL: https://github.com/RobTillaart/Kelvin2RGB
-//
 
 
-#define KELVIN2RGB_LIB_VERSION            (F("0.1.5"))
+#define KELVIN2RGB_LIB_VERSION            (F("0.1.6"))
 
 #include "Arduino.h"
 
@@ -97,5 +96,5 @@ class Kelvin2RGB
 };
 
 
-// -- END OF FILE --
+//  -- END OF FILE --
 

README.md

@@ -13,11 +13,11 @@ Arduino library for converting temperature and brightness to RGB values.
 
 ## Credentials
 
-This library is based upon an article of Tanner Helland
-and a related story by Neil Bartlett
-http://www.tannerhelland.com/4435/convert-temperature-rgb-algorithm-code/
-http://www.zombieprototypes.com/?p=210
-https://en.wikipedia.org/wiki/Color_temperature#Categorizing_different_lighting
+This library is based upon an article of Tanner Helland and a related story by Neil Bartlett
+
+- http://www.tannerhelland.com/4435/convert-temperature-rgb-algorithm-code/
+- http://www.zombieprototypes.com/?p=210
+- https://en.wikipedia.org/wiki/Color_temperature#Categorizing_different_lighting
 
 There are more approximation formulas, some claim to be better,
 however these are not investigated. On request these can be added.
@@ -26,14 +26,14 @@ however these are not investigated. On request these can be added.
 ## Description
 
 The library converts a temperature in Kelvin and a brightness (0..100%)
- to 3 numbers red, green and blue.
+ to three numbers **red**, **green** and **blue**.
 These numbers are weights can be used to correct a colour image for virtual white temperature.
 
-There are 2 convert functions where the **convert_NB()** is claimed to be
+There are two convert functions where the **convert_NB()** is claimed to be
 the more accurate one.
 
-With the numbers R,G,B calculated one can convert images so they will look
-more like taken with candle light, sunrise or sunset etc.
+With the numbers **red**, **green** and **blue** calculated one can convert images 
+so they will look more like taken with candle light, sunrise or sunset etc.
 
 
 **pseudo code**
@@ -51,16 +51,20 @@ for each pixel in image
 }
 ```
 
-The numbers can also be used to reduce the blue channel so it has less effect
+The numbers can also be used to reduce the blue channel so it has less effect 
 on "getting sleepy".
 
 The library uses floats for the R,G and B weights to keep values as accurate as possible.
 Especially with images with more than 8 bits per channel this is preferred.
-That said it is also possible to use this on a 565 image or to adjust color lookup tables.
+That said it is also possible to use this on a 565 image or to adjust colour lookup tables.
 
 
 ## Interface
 
+```cpp
+#include "Kelvin2RGB.h"
+```
+
 The interface is straightforward:
 
 - **Kelvin2RGB()** constructor
@@ -85,8 +89,7 @@ red, green, blue should be in 0 .. 1.0 range. brightness should be in 0..100%, D
 returns a 24 bit RGB value,
 - **uint32_t RGB()** returns a 24 bit RGB value, 0 .. 16777215
 more efficient than 3 floats for communication.
-- **uint16_t RGB565()** returns a 16 bit RGB value,
-5 bits for red, 6 for green and 5 for blue.
+- **uint16_t RGB565()** returns a 16 bit RGB value, 5 bits for red, 6 for green and 5 for blue.
 - **uint32_t BGR()** returns a 24 bit BGR value, 0 .. 16777215
 - **uint32_t CMYK()** returns a 32 bit = 4 byte CMYK value,
 
@@ -98,21 +101,25 @@ See examples
 
 ## Future
 
-#### must
-- add examples
-  - CMYK()
-  - BGR()
+#### Must
+
+#### Should
 
-#### should
 - define constants like candleLight as parameter.
 - investigate other formulas.
-- investigate timing and performance
 - investigate usability for RGB led strip.
-- investigate **RGB_10_12_10()**
 
-#### could
+#### Could
+
 - separate brightness per colour channel to mimic "artificial illumination"  (0.2.0 ?)
 - remove begin() ?
-- example Led-strip()
+- add examples
+  - ledstrip
+  - CMYK()
+  - BGR()
+
+#### Wont
 
+- investigate **RGB_10_12_10()**
+  - nowhere used (not found)
 

examples/Kelvin2RGB_timing/Kelvin2RGB_timing.ino

@@ -34,7 +34,10 @@ void loop()
 void test_timing()
 {
   Serial.println(__FUNCTION__);
+  Serial.print("KELVIN2RGB_LIB_VERSION: ");
+  Serial.println(KELVIN2RGB_LIB_VERSION);
   Serial.println();
+  delay(100);
 
   // volatile to minimize optimization
   volatile float bright = 100.0;
@@ -62,8 +65,60 @@ void test_timing()
   Serial.println(duration2 * 0.001);
   Serial.print("ratio:\t");
   Serial.println(1.0 * duration1 / duration2, 4);
+  Serial.println();
+  delay(100);
+
+  volatile uint32_t RGB;
+  start = micros();
+  for (int i = 0; i < 1000; i++)
+  {
+    RGB = KRGB.RGB();
+  }
+  stop = micros();
+  Serial.print("RGB:\t");
+  Serial.print(stop - start);
+  Serial.print("\t");
+  Serial.println(RGB);
+  delay(100);
+
+  volatile uint32_t CMYK;
+  start = micros();
+  for (int i = 0; i < 1000; i++)
+  {
+    CMYK = KRGB.CMYK();
+  }
+  stop = micros();
+  Serial.print("CMYK:\t");
+  Serial.print(stop - start);
+  Serial.print("\t");
+  Serial.println(CMYK);
+  delay(100);
+
+  volatile uint32_t BGR;
+  start = micros();
+  for (int i = 0; i < 1000; i++)
+  {
+    BGR = KRGB.BGR();
+  }
+  stop = micros();
+  Serial.print("BGR:\t");
+  Serial.print(stop - start);
+  Serial.print("\t");
+  Serial.println(BGR);
+  delay(100);
+
+  volatile uint16_t RGB565;
+  start = micros();
+  for (int i = 0; i < 1000; i++)
+  {
+    RGB565 = KRGB.RGB565();
+  }
+  stop = micros();
+  Serial.print("RGB565:\t");
+  Serial.print(stop - start);
+  Serial.print("\t");
+  Serial.println(RGB565);
 }
 
 
 // -- END OF FILE --
-

examples/Kelvin2RGB_timing/performance_0.1.5.txt

@@ -0,0 +1,18 @@
+IDE 1.8.19
+UNO
+
+Kelvin2RGB_timing.ino
+
+test_timing
+KELVIN2RGB_LIB_VERSION: 0.1.5
+
+TH:	514.05
+NB:	557.81
+ratio:	0.9216
+
+RGB:	760
+CMYK:	936
+BGR:	44540
+RGB565:	552
+
+done...

examples/Kelvin2RGB_timing/performance_0.1.6.txt

@@ -0,0 +1,19 @@
+IDE 1.8.19
+UNO
+
+Kelvin2RGB_timing.ino
+
+test_timing
+KELVIN2RGB_LIB_VERSION: 0.1.6
+
+TH:	514.05
+NB:	557.81
+ratio:	0.9216
+
+RGB:	760	16775934
+CMYK:	888	327680
+BGR:	816	16710399
+RGB565:	544	2015
+
+done...
+

library.json

@@ -15,7 +15,7 @@
     "type": "git",
     "url": "https://github.com/RobTillaart/Kelvin2RGB.git"
   },
-  "version": "0.1.5",
+  "version": "0.1.6",
   "license": "MIT",
   "frameworks": "*",
   "platforms": "*",

library.properties

@@ -1,5 +1,5 @@
 name=Kelvin2RGB
-version=0.1.5
+version=0.1.6
 author=Rob Tillaart <rob.tillaart@gmail.com>
 maintainer=Rob Tillaart <rob.tillaart@gmail.com>
 sentence=Arduino library for converting temperature to RGB values