Conversión de color hexadecimal a RGB y viceversa.

Question

¿Cuál es la forma más eficiente de hacer esto?

Answer 1

Respuesta real: depende del tipo de valor de color hexadecimal que esté buscando (por ejemplo, 565, 555, 888, 8888, etc.), la cantidad de bits alfa, la distribución de color real (rgb vs bgr ...) y una tonelada de otras variables.

Aquí hay un algoritmo genérico para la mayoría de los valores RGB que usan plantillas de C ++ (directamente de 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);
}

Aquí hay una estructura de color de muestra para 565 (el formato estándar para colores de 16 bits):

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

En 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

En python, la conversión entre hexadecimal y 'rgb' también se incluye en el paquete de trazado matplotlib . A saber

import matplotlib.colors as colors

entonces

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

La advertencia es que se supone que los valores rgb en colores están entre 0.0 y 1.0. Si quieres ir entre 0 y 255 necesitas hacer una pequeña conversión. Específicamente,

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])

La otra nota es que colors.hex2color solo acepta cadenas de colores hexadecimales válidas.

Answer 4

simplemente muy rápido:

int r = ( hexcolor >> 16 ) & 0xFF;

int g = ( hexcolor >> 8 ) & 0xFF;

int b = hexcolor & 0xFF;

int hexcolor = (r << 16) + (g << 8) + b;

Answer 5

Modificación de la respuesta python de Jeremy para manejar valores rgb de CSS cortos como 0, # 999 y #fff (que los navegadores mostrarían en negro, gris medio y blanco):

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

Un valor hexadecimal es solo números RGB representados en hexadecimal. Entonces solo tiene que tomar cada par de dígitos hexadecimales y convertirlos a decimales.

Ejemplo:

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

Answer 7

Solo necesita convertir un valor hexadecimal (en partes) a decimal y viceversa. También debe considerarse, qué valor en hexadecimal puede contener 6 o 3 caracteres (sin el carácter '#').

Implementación en Python 3.5

"""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()

Implementación en JavaScript (adaptado a NodeJS con un soporte ES6)

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;

Implementación en la C (destinada a la norma 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_);
}

Un resultado después de la compilación (estoy usando el CCG)

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'

Answer 8

#!/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 9

Este es un fragmento de código que creé para mi propio uso en c ++ 11. puedes enviar valores hexadecimales o cadenas:

    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);