GimpColorSpace: GIMP Color Library Reference Manual

## GimpColorSpace GimpColorSpace — Utility functions which convert colors between different color models. |

## Functions

void | gimp_rgb_to_hsv ()
void | gimp_rgb_to_hsl ()
void | gimp_rgb_to_cmyk ()
void | gimp_hsv_to_rgb ()
void | gimp_hsl_to_rgb ()
void | gimp_cmyk_to_rgb ()
void | gimp_rgb_to_hwb ()
void | gimp_hwb_to_rgb ()
void | gimp_rgb_to_hsv_int ()
void | gimp_hsv_to_rgb_int ()
void | gimp_rgb_to_hsl_int ()
void | gimp_rgb_to_cmyk_int ()
void | gimp_cmyk_to_rgb_int ()
gint | gimp_rgb_to_l_int ()
void | gimp_hsl_to_rgb_int ()
void | gimp_rgb_to_hsv4 ()
void | gimp_hsv_to_rgb4 ()

## Description

When programming pixel data manipulation functions you will often use algorithms operating on a color model different from the one GIMP uses. This file provides utility functions to convert colors between different color spaces.

## Functions

### gimp_rgb_to_hsv ()

    void
    gimp_rgb_to_hsv (const GimpRGB *rgb,
                     GimpHSV *hsv);

Does a conversion from RGB to HSV (Hue, Saturation, Value) colorspace.

#### Parameters

rgb | A color value in the RGB colorspace |
hsv | The value converted to the HSV colorspace |

### gimp_rgb_to_hsl ()

    void
    gimp_rgb_to_hsl (const GimpRGB *rgb,
                     GimpHSL *hsl);

Convert an RGB color value to a HSL (Hue, Saturation, Lightness) color value.

#### Parameters

rgb | A color value in the RGB colorspace |
hsl | The value converted to HSL |

### gimp_rgb_to_cmyk ()

    void
    gimp_rgb_to_cmyk (const GimpRGB *rgb,
                      gdouble pullout,
                      GimpCMYK *cmyk);

Does a naive conversion from RGB to CMYK colorspace. A simple formula that doesn't take any color-profiles into account is used. The amount of black pullout how can be controlled via the `pullout` parameter. A `pullout` value of 0 makes this a conversion to CMY. A value of 1 causes the maximum amount of black to be pulled out.

#### Parameters

rgb | A value in the RGB colorspace |
pullout | A scaling value (0-1) indicating how much black should be pulled out |
cmyk | The input value naively converted to the CMYK colorspace |

### gimp_hsv_to_rgb ()

    void
    gimp_hsv_to_rgb (const GimpHSV *hsv,
                     GimpRGB *rgb);

Converts a color value from HSV to RGB colorspace

#### Parameters

hsv | A color value in the HSV colorspace |
rgb | The returned RGB value. |

### gimp_hsl_to_rgb ()

    void
    gimp_hsl_to_rgb (const GimpHSL *hsl,
                     GimpRGB *rgb);

Convert a HSL color value to an RGB color value.

#### Parameters

hsl | A color value in the HSL colorspace |
rgb | The value converted to a value in the RGB colorspace |

### gimp_cmyk_to_rgb ()

    void
    gimp_cmyk_to_rgb (const GimpCMYK *cmyk,
                      GimpRGB *rgb);

Does a simple transformation from the CMYK colorspace to the RGB colorspace, without taking color profiles into account.

#### Parameters

cmyk | A color value in the CMYK colorspace |
rgb | The value converted to the RGB colorspace |

### gimp_rgb_to_hwb ()

    void
    gimp_rgb_to_hwb (const GimpRGB *rgb,
                     gdouble *hue,
                     gdouble *whiteness,
                     gdouble *blackness);

`gimp_rgb_to_hwb` is deprecated and should not be used in newly-written code.

Theoretically, hue 0 (pure red) is identical to hue 6 in these transforms. Pure red always maps to 6 in this implementation. Therefore UNDEFINED can be defined as 0 in situations where only unsigned numbers are desired.

RGB are each on [0, 1]. Whiteness and Blackness are returned in the range [0, 1] and H is returned in the range [0, 6]. If W == 1 - B, H is undefined.

#### Parameters

rgb | A color value in the RGB colorspace |
hue | The hue value of the above color, in the range 0 to 6 |
whiteness | The whiteness value of the above color, in the range 0 to 1 |
blackness | The blackness value of the above color, in the range 0 to 1 |

### gimp_hwb_to_rgb ()

    void
    gimp_hwb_to_rgb (gdouble hue,
                     gdouble whiteness,
                     gdouble blackness,
                     GimpRGB *rgb);

`gimp_hwb_to_rgb` is deprecated and should not be used in newly-written code.

H is defined in the range [0, 6] or UNDEFINED, B and W are both in the range [0, 1]. The returned RGB values are all in the range [0, 1].

#### Parameters

hue | A hue value, in the range 0 to 6 |
whiteness | A whiteness value, in the range 0 to 1 |
blackness | A blackness value, in the range 0 to 1 |
rgb | The above color converted to the RGB colorspace |

### gimp_rgb_to_hsv_int ()

    void
    gimp_rgb_to_hsv_int (gint *red,
                         gint *green,
                         gint *blue);

`gimp_rgb_to_hsv_int` is deprecated and should not be used in newly-written code.

The arguments are pointers to int representing channel values in the RGB colorspace, and the values pointed to are all in the range [0, 255].

The function changes the arguments to point to the HSV value corresponding, with the returned values in the following ranges: H [0, 359], S [0, 255], V [0, 255].

#### Parameters

red | The red channel value, returns the Hue channel |
green | The green channel value, returns the Saturation channel |
blue | The blue channel value, returns the Value channel |

### gimp_hsv_to_rgb_int ()

    void
    gimp_hsv_to_rgb_int (gint *hue,
                         gint *saturation,
                         gint *value);

`gimp_hsv_to_rgb_int` is deprecated and should not be used in newly-written code.

The arguments are pointers to int, with the values pointed to in the following ranges: H [0, 360], S [0, 255], V [0, 255].

The function changes the arguments to point to the RGB value corresponding, with the returned values all in the range [0, 255].

#### Parameters

hue | The hue channel, returns the red channel |
saturation | The saturation channel, returns the green channel |
value | The value channel, returns the blue channel |

### gimp_rgb_to_hsl_int ()

    void
    gimp_rgb_to_hsl_int (gint *red,
                         gint *green,
                         gint *blue);

`gimp_rgb_to_hsl_int` is deprecated and should not be used in newly-written code.

The arguments are pointers to int representing channel values in the RGB colorspace, and the values pointed to are all in the range [0, 255].

The function changes the arguments to point to the corresponding HLS value with the values pointed to in the following ranges: H [0, 360], L [0, 255], S [0, 255].

#### Parameters

red | Red channel, returns Hue channel |
green | Green channel, returns Lightness channel |
blue | Blue channel, returns Saturation channel |

### gimp_rgb_to_cmyk_int ()

    void
    gimp_rgb_to_cmyk_int (gint *red,
                          gint *green,
                          gint *blue,
                          gint *pullout);

`gimp_rgb_to_cmyk_int` is deprecated and should not be used in newly-written code.

Does a naive conversion from RGB to CMYK colorspace. A simple formula that doesn't take any color-profiles into account is used. The amount of black pullout how can be controlled via the `pullout` parameter. A `pullout` value of 0 makes this a conversion to CMY. A value of 100 causes the maximum amount of black to be pulled out.

#### Parameters

red | the red channel; returns the cyan value (0-255) |
green | the green channel; returns the magenta value (0-255) |
blue | the blue channel; returns the yellow value (0-255) |
pullout | the percentage of black to pull out (0-100); returns the black value (0-255) |

### gimp_cmyk_to_rgb_int ()

    void
    gimp_cmyk_to_rgb_int (gint *cyan,
                          gint *magenta,
                          gint *yellow,
                          gint *black);

`gimp_cmyk_to_rgb_int` is deprecated and should not be used in newly-written code.

Does a naive conversion from CMYK to RGB colorspace. A simple formula that doesn't take any color-profiles into account is used.

#### Parameters

cyan | the cyan channel; returns the red value (0-255) |
magenta | the magenta channel; returns the green value (0-255) |
yellow | the yellow channel; returns the blue value (0-255) |
black | the black channel (0-255); doesn't change |

### gimp_rgb_to_l_int ()

    gint
    gimp_rgb_to_l_int (gint red,
                       gint green,
                       gint blue);

`gimp_rgb_to_l_int` is deprecated and should not be used in newly-written code.

Calculates the lightness value of an RGB triplet with the formula L = (max(R, G, B) + min (R, G, B)) / 2

#### Parameters

red | Red channel |
green | Green channel |
blue | Blue channel |

#### Returns

Luminance value corresponding to the input RGB value

### gimp_hsl_to_rgb_int ()

    void
    gimp_hsl_to_rgb_int (gint *hue,
                         gint *saturation,
                         gint *lightness);

`gimp_hsl_to_rgb_int` is deprecated and should not be used in newly-written code.

The arguments are pointers to int, with the values pointed to in the following ranges: H [0, 360], L [0, 255], S [0, 255].

The function changes the arguments to point to the RGB value corresponding, with the returned values all in the range [0, 255].

#### Parameters

hue | Hue channel, returns Red channel |
saturation | Saturation channel, returns Green channel |
lightness | Lightness channel, returns Blue channel |

### gimp_rgb_to_hsv4 ()

    void
    gimp_rgb_to_hsv4 (const guchar *rgb,
                      gdouble *hue,
                      gdouble *saturation,
                      gdouble *value);

`gimp_rgb_to_hsv4` is deprecated and should not be used in newly-written code.

#### Parameters

rgb | RGB triplet, rgb[0] is red channel, rgb[1] is green, rgb[2] is blue (0..255) |
hue | Pointer to hue channel (0..1) |
saturation | Pointer to saturation channel (0..1) |
value | Pointer to value channel (0..1) |

### gimp_hsv_to_rgb4 ()

    void
    gimp_hsv_to_rgb4 (guchar *rgb,
                      gdouble hue,
                      gdouble saturation,
                      gdouble value);

`gimp_hsv_to_rgb4` is deprecated and should not be used in newly-written code.

#### Parameters

rgb | RGB triplet, rgb[0] is red channel, rgb[1] is green, rgb[2] is blue (0..255) |
hue | Hue channel (0..1) |
saturation | Saturation channel (0..1) |
value | Value channel (0..1) |