Convert hex color to RGB and vice versa

Question

What is the most efficient way to do this?

Answer 1

The real answer: depends on what kind of hexadecimal color value you are looking for (e.g. 565, 555, 888, 8888, etc.), the number of alpha bits, the actual distribution of colors (rgb vs bgr ...) and tons of others variables.

Here is a general algorithm for most RGB values ​​using C ++ templates (straight from ScummVM).

template<class T> uint32 RGBToColor(uint8 r, uint8 g, uint8 b) { return T::kAlphaMask | (((r << T::kRedShift) >> (8 - T::kRedBits)) & T::kRedMask) | (((g << T::kGreenShift) >> (8 - T::kGreenBits)) & T::kGreenMask) | (((b << T::kBlueShift) >> (8 - T::kBlueBits)) & T::kBlueMask); } 

Here's a sample color structure for 565 (standard format for 16-bit colors):

 template<> struct ColorMasks<565> { enum { highBits = 0xF7DEF7DE, lowBits = 0x08210821, qhighBits = 0xE79CE79C, qlowBits = 0x18631863, kBytesPerPixel = 2, kAlphaBits = 0, kRedBits = 5, kGreenBits = 6, kBlueBits = 5, kAlphaShift = kRedBits+kGreenBits+kBlueBits, kRedShift = kGreenBits+kBlueBits, kGreenShift = kBlueBits, kBlueShift = 0, kAlphaMask = ((1 << kAlphaBits) - 1) << kAlphaShift, kRedMask = ((1 << kRedBits) - 1) << kRedShift, kGreenMask = ((1 << kGreenBits) - 1) << kGreenShift, kBlueMask = ((1 << kBlueBits) - 1) << kBlueShift, kRedBlueMask = kRedMask | kBlueMask }; }; 

Answer 2

In python:

 def hex_to_rgb(value): """Return (red, green, blue) for the color given as #rrggbb.""" value = value.lstrip('#') lv = len(value) return tuple(int(value[i:i + lv // 3], 16) for i in range(0, lv, lv // 3)) def rgb_to_hex(red, green, blue): """Return color as #rrggbb for the given color values.""" return '#%02x%02x%02x' % (red, green, blue) hex_to_rgb("#ffffff") #==> (255, 255, 255) hex_to_rgb("#ffffffffffff") #==> (65535, 65535, 65535) rgb_to_hex(255, 255, 255) #==> '#ffffff' rgb_to_hex(65535, 65535, 65535) #==> '#ffffffffffff' 

Answer 3

In the python conversion between hexadecimal and 'rgb' is also included in the matplotlib build matplotlib . Namely

 import matplotlib.colors as colors 

Then

 colors.hex2color('#ffffff') #==> (1.0, 1.0, 1.0) colors.rgb2hex((1.0, 1.0, 1.0)) #==> '#ffffff' 

The caveat is that rgb values ​​in colors count between 0.0 and 1.0. If you want to go from 0 to 255, you need to do a little conversion. In particular,

 def hex_to_rgb(hex_string): rgb = colors.hex2color(hex_string) return tuple([int(255*x) for x in rgb]) def rgb_to_hex(rgb_tuple): return colors.rgb2hex([1.0*x/255 for x in rgb_tuple]) 

Another note is that colors.hex2color only accepts valid hexadecimal color strings.

Answer 4

just fast:

 int r = ( hexcolor >> 16 ) & 0xFF; int g = ( hexcolor >> 8 ) & 0xFF; int b = hexcolor & 0xFF; int hexcolor = (r << 16) + (g << 8) + b; 

Answer 5

Changing python's answer to Jeremy to handle short CSS rgb values ​​like 0, # 999 and #fff (which browsers will display as black, medium gray and white):

 def hex_to_rgb(value): value = value.lstrip('#') lv = len(value) if lv == 1: v = int(value, 16)*17 return v, v, v if lv == 3: return tuple(int(value[i:i+1], 16)*17 for i in range(0, 3)) return tuple(int(value[i:i+lv/3], 16) for i in range(0, lv, lv/3)) 

Answer 6

A hexadecimal value is only RGB numbers represented in hexadecimal format. So you just need to take each pair of hexadecimal digits and convert them to decimal.

Example:

 #FF6400 = RGB(0xFF, 0x64, 0x00) = RGB(255, 100, 0) 

Answer 7

 #! / usr / bin / env python

 import re
 import sys

 def hex_to_rgb (value):
   value = value.lstrip ('#')
   lv = len (value)
   return tuple (int (value [i: i + lv / 3], 16) for i in range (0, lv, lv / 3))

 def rgb_to_hex (rgb):
   rgb = eval (rgb)
   r = rgb [0]
   g = rgb [1]
   b = rgb [2]
   return '#% 02X% 02X% 02X'% (r, g, b)

 def main ():
   color = raw_input ("HEX [#FFFFFF] or RGB [255, 255, 255] value (no value quits program):")
   while color:
     if re.search ('\ # [a-fA-F0-9] [a-fA-F0-9] [a-fA-F0-9] [a-fA-F0-9] [a-fA-F0 -9] [a-fA-F0-9] ', color):
       converted = hex_to_rgb (color)
       print converted
     elif re.search ('[0-9] {1,3}, [0-9] {1,3}, [0-9] {1,3}', color):
       converted = rgb_to_hex (color)
       print converted
     elif color == '':
       sys.exit (0)
     else:
       print 'You didn \' t enter a valid value! '
     color = raw_input ("HEX [#FFFFFF] or RGB [255, 255, 255] value (no value quits program):")

 if __name__ == '__main__':
   main ()

Answer 8

This is a piece of code that I created for my own use in C ++ 11. you can send hexadecimal values ​​or strings:

  void Color::SetColor(string color) { // try catch will be necessary if your string is not sanitized before calling this function. SetColor(std::stoul(color, nullptr, 16)); } void Color::SetColor(uint32_t number) { B = number & 0xFF; number>>= 8; G = number & 0xFF; number>>= 8; R = number & 0xFF; } // ex: SetColor("ffffff"); SetColor(0xFFFFFF); 

Answer 9

You only need to convert the hex value (in parts) to decimal and vice versa. It is also necessary to consider what value in hexadecimal can contain 6 or 3 characters (without the '#' character).

Python 3.5 implementation

 """Utils for working with colors.""" import textwrap def rgb_to_hex(value1, value2, value3): """ Convert RGB value (as three numbers each ranges from 0 to 255) to hex format. >>> rgb_to_hex(235, 244, 66) '#EBF442' >>> rgb_to_hex(56, 28, 26) '#381C1A' >>> rgb_to_hex(255, 255, 255) '#FFFFFF' >>> rgb_to_hex(0, 0, 0) '#000000' >>> rgb_to_hex(203, 244, 66) '#CBF442' >>> rgb_to_hex(53, 17, 8) '#351108' """ for value in (value1, value2, value3): if not 0 <= value <= 255: raise ValueError('Value each slider must be ranges from 0 to 255') return '#{0:02X}{1:02X}{2:02X}'.format(value1, value2, value3) def hex_to_rgb(value): """ Convert color`s value in hex format to RGB format. >>> hex_to_rgb('fff') (255, 255, 255) >>> hex_to_rgb('ffffff') (255, 255, 255) >>> hex_to_rgb('#EBF442') (235, 244, 66) >>> hex_to_rgb('#000000') (0, 0, 0) >>> hex_to_rgb('#000') (0, 0, 0) >>> hex_to_rgb('#54433f') (84, 67, 63) >>> hex_to_rgb('#f7efed') (247, 239, 237) >>> hex_to_rgb('#191616') (25, 22, 22) """ if value[0] == '#': value = value[1:] len_value = len(value) if len_value not in [3, 6]: raise ValueError('Incorect a value hex {}'.format(value)) if len_value == 3: value = ''.join(i * 2 for i in value) return tuple(int(i, 16) for i in textwrap.wrap(value, 2)) if __name__ == '__main__': import doctest doctest.testmod() 

JavaScript implementation (adapted to NodeJS with ES6 support)

 const assert = require('assert'); /** * Return a color`s value in the hex format by passed the RGB format. * @param {integer} value1 An value in ranges from 0 to 255 * @param {integer} value2 An value in ranges from 0 to 255 * @param {integer} value3 An value in ranges from 0 to 255 * @return {string} A color`s value in the hex format */ const RGBtoHex = (value1, value2, value3) => { const values = [value1, value2, value3]; let result = '#'; for (let i = 0; i < 3; i += 1) { // validation input if (values[i] < 0 || values[i] > 255) throw new Error('An each value of RGB format must be ranges from 0 to 255'); // append to result values as hex with at least width 2 result += (('0' + values[i].toString(16)).slice(-2)); } return result.toUpperCase(); }; /** * Convert a value from the hex format to RGB and return as an array * @param {int} value A color`s value in the hex format * @return {array} Array values of the RGB format */ const hexToRGB = (value) => { let val = value; val = (value[0] === '#') ? value.slice(1) : value; if ([3, 6].indexOf(val.length) === -1) throw new Error(`Incorect a value of the hex format: ${value}`); if (val.length === 3) val = val.split('').map(item => item.repeat(2)).join(''); return val.match(/.{2}/g).map(item => parseInt(`0x${item}`, 16)); }; assert.deepEqual(hexToRGB('fff'), [255, 255, 255]); assert.deepEqual(hexToRGB('#fff'), [255, 255, 255]); assert.deepEqual(hexToRGB('#000000'), [0, 0, 0]); assert.deepEqual(hexToRGB('000000'), [0, 0, 0]); assert.deepEqual(hexToRGB('#d7dee8'), [215, 222, 232]); assert.deepEqual(hexToRGB('#1E2F49'), [30, 47, 73]); assert.deepEqual(hexToRGB('#030914'), [3, 9, 20]); assert.equal(RGBtoHex(255, 255, 255), '#FFFFFF'); assert.equal(RGBtoHex(0, 0, 0), '#000000'); assert.equal(RGBtoHex(96, 102, 112), '#606670'); assert.equal(RGBtoHex(199, 204, 214), '#C7CCD6'); assert.equal(RGBtoHex(22, 99, 224), '#1663E0'); assert.equal(RGBtoHex(0, 8, 20), '#000814'); module.exports.RGBtoHex = RGBtoHex; module.exports.hexToRGB = hexToRGB; 

C implementation (designed for standard C11)

 // a type for a struct of RGB color typedef struct _ColorRGB { unsigned short int red; unsigned short int green; unsigned short int blue; } colorRGB_t; /* Convert a color`s value from the hex format to the RGB. Return -1 if a passed value in the hex format is not correct, otherwise - return 0; */ static int convertColorHexToRGB(const char originValue[], colorRGB_t *colorRGB) { // a full value of color in hex format must constains 6 charapters char completedValue[6]; size_t lenOriginValue; size_t lenCompletedValue; // an intermediary variable for keeping value in the hex format char hexSingleValue[3]; // a temp pointer to char, need only to the strtol() char *ptr; // a variable for keeping a converted number in the hex to the decimal format long int number; // validation input lenOriginValue = strlen(originValue); if (lenOriginValue > 7 || lenOriginValue < 3) return -1; // copy value without sign '#', if found as first in the string (originValue[0] == '#') ? strcpy(completedValue, originValue + 1) : strcpy(completedValue, originValue); lenCompletedValue = strlen(completedValue); // if the value has only 3 charapters, dublicate an each after itself // but if not full version of the hex name of a color (6 charapters), return -1 if (lenCompletedValue == 3) { completedValue[5] = completedValue[2]; completedValue[4] = completedValue[2]; completedValue[3] = completedValue[1]; completedValue[2] = completedValue[1]; completedValue[1] = completedValue[0]; } else if (lenCompletedValue != 6) return -1; // convert string, by parts, to decimal values and keep it in a struct sprintf(hexSingleValue, "%c%c", completedValue[0], completedValue[1]); number = strtol(hexSingleValue, &ptr, 16); colorRGB->red = number; sprintf(hexSingleValue, "%c%c", completedValue[2], completedValue[3]); number = strtol(hexSingleValue, &ptr, 16); colorRGB->green = number; sprintf(hexSingleValue, "%c%c", completedValue[4], completedValue[5]); number = strtol(hexSingleValue, &ptr, 16); colorRGB->blue = number; return 0; } /* Convert a color`s value from the RGB format to the hex */ static int convertColorRGBToHex(const colorRGB_t *colorRGB, char value[8]) { sprintf(value, "#%02X%02X%02X", colorRGB->red, colorRGB->green, colorRGB->blue); return 0; } /* Forming a string representation data in an instance of the structure colorRGB_t */ static int getRGBasString(const colorRGB_t *colorRGB, char str[18]) { sprintf(str, "rgb(%d, %d, %d)", colorRGB->red, colorRGB->green, colorRGB->blue); return 0; } int main (int argv, char **argc) { char str[18]; char hex[8]; colorRGB_t *colorRGB_; colorRGB_ = (colorRGB_t *)malloc(sizeof(colorRGB_)); convertColorHexToRGB("fff", colorRGB_); getRGBasString(colorRGB_, str); printf("Hex 'fff' to RGB %s\n", str); convertColorRGBToHex(colorRGB_, hex); printf("RGB %s to hex '%s'\n", str, hex); convertColorHexToRGB("000000", colorRGB_); getRGBasString(colorRGB_, str); printf("Hex '000000' to RGB %s\n", str); convertColorRGBToHex(colorRGB_, hex); printf("RGB %s to hex '%s'\n", str, hex); convertColorHexToRGB("#000000", colorRGB_); getRGBasString(colorRGB_, str); printf("Hex '#000000' to RGB %s\n", str); convertColorRGBToHex(colorRGB_, hex); printf("RGB %s to hex '%s'\n", str, hex); convertColorHexToRGB("#FFF", colorRGB_); getRGBasString(colorRGB_, str); printf("Hex '#FFF' to RGB %s\n", str); convertColorRGBToHex(colorRGB_, hex); printf("RGB %s to hex '%s'\n", str, hex); free(colorRGB_); } 

Result after compilation (I use GCC)

 Hex 'fff' to RGB rgb(255, 255, 255) RGB rgb(255, 255, 255) to hex '#FFFFFF' Hex '000000' to RGB rgb(0, 0, 0) RGB rgb(0, 0, 0) to hex '#000000' Hex '#000000' to RGB rgb(0, 0, 0) RGB rgb(0, 0, 0) to hex '#000000' Hex '#FFF' to RGB rgb(255, 255, 255) RGB rgb(255, 255, 255) to hex '#FFFFFF'