• VIPS_INTERPRETATION_LAB -- CIELAB '76 colourspace with a D65 white. Thisuses three floats for each band, and bands have the obvious range.

  There are twovariants,VIPS_INTERPRETATION_LABQ andVIPS_INTERPRETATION_LABS, whichuse ints to store values. These are less precise, but can be quicker tostore and process.

  VIPS_INTERPRETATION_LCH is the same, but with a*b* as polar coordinates.Hue is expressed in degrees.

• VIPS_INTERPRETATION_XYZ -- CIE XYZ. This uses three floats.SeeVIPS_D75_X0 and friends for values for the rangesunder various illuminants.

  VIPS_INTERPRETATION_YXY is the same, but with little x and y.

• VIPS_INTERPRETATION_scRGB -- a linear colourspace with the sRGBprimaries. This is useful if you need linear light and don't caremuch what the primaries are.

  Linearization is performed with the usual sRGB equations, see below.

• VIPS_INTERPRETATION_sRGB -- the standard sRGB colourspace, see:wikipedia sRGB.

  This uses three 8-bit values for each of RGB.

  VIPS_INTERPRETATION_RGB16 is the same, but using three 16-bit values forRGB.

  VIPS_INTERPRETATION_HSV is sRGB, but in polar coordinates.VIPS_INTERPRETATION_LCH is much better, only use HSV if you have to.

• VIPS_INTERPRETATION_B_W -- a monochrome image, roughly G from sRGB.The grey value iscalculated in linearVIPS_INTERPRETATION_scRGB space with RGB ratios0.2126, 0.7152, 0.0722 as defined by CIE 1931 linear luminance.

  VIPS_INTERPRETATION_GREY16 is the same, but using 16 bits.

• VIPS_INTERPRETATION_CMC -- a colour space based on the CMC(1:1)colour difference measurement. This is a highly uniform colour space,and much better than CIELAB for expressing small differences.

  The CMC colourspace is described in "Uniform Colour Space Based on theCMC(l:c) Colour-difference Formula", M R Luo and B Rigg, Journal of theSociety of Dyers and Colourists, vol 102, 1986. Distances in thiscolourspace approximate, within 10% or so, differences in the CMC(l:c)colour difference formula.

  You can calculate metrics like CMC(2:1) by scaling the spaces beforefinding differences.

vips_colourspace_issupported ()

gbooleanvips_colourspace_issupported (constVipsImage *image);

Test ifimage is in a colourspace thatvips_colourspace() can process.

[method]

vips_colourspace ()

intvips_colourspace (VipsImage *in,VipsImage **out,VipsInterpretation space,...);

Optional arguments:

This operation looks at the interpretation field ofin (or usessource_space, if set) and runsa set of colourspace conversion functions to move it tospace.

For example, given an image tagged asVIPS_INTERPRETATION_YXY, runningvips_colourspace() withspace set toVIPS_INTERPRETATION_LAB willconvert withvips_Yxy2XYZ() andvips_XYZ2Lab().

See also:vips_colourspace_issupported(),vips_image_guess_interpretation().

[method]

vips_LabQ2sRGB ()

intvips_LabQ2sRGB (VipsImage *in,VipsImage **out,...);

Unpack a LabQ (VIPS_CODING_LABQ) image to a three-band short image.

See also:vips_LabS2LabQ(),vips_LabQ2sRGB(),vips_rad2float().

[method]

vips_rad2float ()

intvips_rad2float (VipsImage *in,VipsImage **out,...);

Unpack a RAD (VIPS_CODING_RAD) image to a three-band float image.

See also:vips_float2rad(),vips_LabQ2LabS().

[method]

vips_float2rad ()

intvips_float2rad (VipsImage *in,VipsImage **out,...);

Convert a three-band float image to Radiance 32-bit packed format.

See also:vips_rad2float(),VIPS_CODING_RAD,vips_LabQ2Lab().

[method]

vips_LabS2LabQ ()

intvips_LabS2LabQ (VipsImage *in,VipsImage **out,...);

Convert a LabS three-band signed short image to LabQ

See also:vips_LabQ2LabS().

[method]

vips_LabQ2LabS ()

intvips_LabQ2LabS (VipsImage *in,VipsImage **out,...);

Unpack a LabQ (VIPS_CODING_LABQ) image to a three-band short image.

See also:vips_LabS2LabQ(),vips_LabQ2LabS(),vips_rad2float().

[method]

vips_LabQ2Lab ()

intvips_LabQ2Lab (VipsImage *in,VipsImage **out,...);

Unpack a LabQ (VIPS_CODING_LABQ) image to a three-band float image.

See also:vips_LabQ2Lab(),vips_LabQ2LabS(),vips_rad2float().

[method]

vips_Lab2LabQ ()

intvips_Lab2LabQ (VipsImage *in,VipsImage **out,...);

Convert a Lab three-band float image to LabQ (VIPS_CODING_LABQ).

See also:vips_LabQ2Lab().

[method]

vips_LCh2Lab ()

intvips_LCh2Lab (VipsImage *in,VipsImage **out,...);

Turn LCh to Lab.

[method]

vips_Lab2LCh ()

intvips_Lab2LCh (VipsImage *in,VipsImage **out,...);

Turn Lab to LCh.

[method]

vips_Yxy2Lab ()

intvips_Yxy2Lab (VipsImage *in,VipsImage **out,...);

vips_CMC2XYZ ()

intvips_CMC2XYZ (VipsImage *in,VipsImage **out,...);

vips_Lab2XYZ ()

intvips_Lab2XYZ (VipsImage *in,VipsImage **out,...);

Optional arguments:

Turn Lab to XYZ. The colour temperature defaults to D65, but can bespecified withtemp.

[method]

vips_XYZ2Lab ()

intvips_XYZ2Lab (VipsImage *in,VipsImage **out,...);

Optional arguments:

Turn XYZ to Lab, optionally specifying the colour temperature.tempdefaults to D65.

[method]

vips_XYZ2scRGB ()

intvips_XYZ2scRGB (VipsImage *in,VipsImage **out,...);

Turn XYZ to scRGB.

[method]

vips_scRGB2sRGB ()

intvips_scRGB2sRGB (VipsImage *in,VipsImage **out,...);

Optional arguments:

Convert an scRGB image to sRGB. Setdepth to 16 to get 16-bit output.

Ifdepth is 16, any extra channels after RGB aremultiplied by 256.

See also:vips_LabS2LabQ(),vips_sRGB2scRGB(),vips_rad2float().

[method]

vips_scRGB2BW ()

intvips_scRGB2BW (VipsImage *in,VipsImage **out,...);

Optional arguments:

Convert an scRGB image to greyscale. Setdepth to 16 to get 16-bit output.

Ifdepth is 16, any extra channels after RGB aremultiplied by 256.

See also:vips_LabS2LabQ(),vips_sRGB2scRGB(),vips_rad2float().

[method]

vips_sRGB2scRGB ()

intvips_sRGB2scRGB (VipsImage *in,VipsImage **out,...);

Convert an sRGB image to scRGB. The input image can be 8 or 16-bit.

If the input image is tagged asVIPS_INTERPRETATION_RGB16, any extrachannels after RGB are divided by 256. Thus, scRGB alpha isalways 0 - 255.99.

See also:vips_scRGB2XYZ(),vips_scRGB2sRGB(),vips_rad2float().

[method]

vips_scRGB2XYZ ()

intvips_scRGB2XYZ (VipsImage *in,VipsImage **out,...);

Turn XYZ to scRGB.

[method]

vips_HSV2sRGB ()

intvips_HSV2sRGB (VipsImage *in,VipsImage **out,...);

Convert HSV to sRGB.

HSV is a crude polar coordinate system for RGB images. It is provided forcompatibility with other image processing systems. Seevips_Lab2LCh() for amuch better colour space.

See also:vips_sRGB2HSV().

[method]

vips_sRGB2HSV ()

intvips_sRGB2HSV (VipsImage *in,VipsImage **out,...);

Convert to HSV.

HSV is a crude polar coordinate system for RGB images. It is provided forcompatibility with other image processing systems. Seevips_Lab2LCh() for amuch better colour space.

See also:vips_HSV2sRGB(),vips_Lab2LCh().

[method]

vips_LCh2CMC ()

intvips_LCh2CMC (VipsImage *in,VipsImage **out,...);

Turn LCh to CMC.

The CMC colourspace is described in "Uniform Colour Space Based on theCMC(l:c) Colour-difference Formula", M R Luo and B Rigg, Journal of theSociety of Dyers and Colourists, vol 102, 1986. Distances in thiscolourspace approximate, within 10% or so, differences in the CMC(l:c)colour difference formula.

This operation generates CMC(1:1). For CMC(2:1), halve Lucs and doubleCucs.

See also:vips_CMC2LCh().

[method]

vips_CMC2LCh ()

intvips_CMC2LCh (VipsImage *in,VipsImage **out,...);

Turn LCh to CMC.

See also:vips_LCh2CMC().

[method]

vips_XYZ2Yxy ()

intvips_XYZ2Yxy (VipsImage *in,VipsImage **out,...);

Turn XYZ to Yxy.

[method]

vips_Yxy2XYZ ()

intvips_Yxy2XYZ (VipsImage *in,VipsImage **out,...);

Turn XYZ to Yxy.

[method]

vips_LabS2Lab ()

intvips_LabS2Lab (VipsImage *in,VipsImage **out,...);

Convert a LabS three-band signed short image to a three-band float image.

See also:vips_LabS2Lab().

[method]

vips_Lab2LabS ()

intvips_Lab2LabS (VipsImage *in,VipsImage **out,...);

Turn Lab to LabS, signed 16-bit int fixed point.

See also:vips_LabQ2Lab().

[method]

vips_CMYK2XYZ ()

intvips_CMYK2XYZ (VipsImage *in,VipsImage **out,...);

Turn CMYK to XYZ. If the image has an embedded ICC profile this will beused for the conversion. If there is no embedded profile, a genericfallback profile will be used.

Conversion is to D65 XYZ with relative intent. If you need more controlover the process, usevips_icc_import() instead.

[method]

vips_XYZ2CMYK ()

intvips_XYZ2CMYK (VipsImage *in,VipsImage **out,...);

Turn XYZ to CMYK.

Conversion is from D65 XYZ with relative intent. If you need more controlover the process, usevips_icc_export() instead.

[method]

vips_profile_load ()

intvips_profile_load (constchar *name,VipsBlob **profile,...);

Load a named profile.

Profiles are loaded from four sources:

vips_icc_present ()

intvips_icc_present (void);

VIPS can optionally be built without the ICC library. Use this function totest for its availability.

vips_icc_transform ()

intvips_icc_transform (VipsImage *in,VipsImage **out,constchar *output_profile,...);

Optional arguments:

Transform an image with a pair of ICC profiles. The input image is moved toprofile-connection space with the input profile and then to the outputspace with the output profile.

The input profile is searched for in three places:

Ifblack_point_compensation is set, LCMS black point compensation isenabled.

depth defaults to 8, or 16 ifin is a 16-bit image.

The output image has the output profile attached to theVIPS_META_ICC_NAMEfield.

Usevips_icc_import() andvips_icc_export() to do either the first orsecond half of this operation in isolation.

[method]

vips_icc_import ()

intvips_icc_import (VipsImage *in,VipsImage **out,...);

Optional arguments:

Import an image from device space to D65 LAB with an ICC profile. Ifpcs isset toVIPS_PCS_XYZ, use CIE XYZ PCS instead.

The input profile is searched for in three places:

Ifblack_point_compensation is set, LCMS black point compensation isenabled.

[method]

vips_icc_export ()

intvips_icc_export (VipsImage *in,VipsImage **out,...);

Optional arguments:

Export an image from D65 LAB to device space with an ICC profile.Ifpcs isset toVIPS_PCS_XYZ, use CIE XYZ PCS instead.Ifoutput_profile is not set, use the embedded profile, if any.Ifoutput_profile is set, export with that and attach it to the outputimage.

Ifblack_point_compensation is set, LCMS black point compensation isenabled.

[method]

vips_icc_ac2rc ()

intvips_icc_ac2rc (VipsImage *in,VipsImage **out,constchar *profile_filename);

Transform an image from absolute to relative colorimetry using theMediaWhitePoint stored in the ICC profile.

See also:vips_icc_transform(),vips_icc_import().

[method]

vips_icc_is_compatible_profile ()

gbooleanvips_icc_is_compatible_profile (VipsImage *image,constvoid *data,size_t data_length);

vips_dE76 ()

intvips_dE76 (VipsImage *left,VipsImage *right,VipsImage **out,...);

Calculate dE 76.

vips_dE00 ()

intvips_dE00 (VipsImage *left,VipsImage *right,VipsImage **out,...);

Calculate dE 00.

vips_dECMC ()

intvips_dECMC (VipsImage *left,VipsImage *right,VipsImage **out,...);

Calculate dE CMC. The input images are transformed to CMC colour space andthe euclidean distance between corresponding pixels calculated.

To calculate a colour difference with values for (l:c) other than (1:1),transform the two source images to CMC yourself, scale the channelsappropriately, and call this function.

See also:vips_colourspace()

vips_col_Lab2XYZ ()

voidvips_col_Lab2XYZ (float L,float a,float b,float *X,float *Y,float *Z);

Calculate XYZ from Lab, D65.

See also:vips_Lab2XYZ().

vips_col_XYZ2Lab ()

voidvips_col_XYZ2Lab (float X,float Y,float Z,float *L,float *a,float *b);

Calculate XYZ from Lab, D65.

See also:vips_XYZ2Lab().

vips_col_ab2h ()

doublevips_col_ab2h (double a,double b);

vips_col_ab2Ch ()

voidvips_col_ab2Ch (float a,float b,float *C,float *h);

vips_col_Ch2ab ()

voidvips_col_Ch2ab (float C,float h,float *a,float *b);

Calculate ab from Ch, h in degrees.

vips_col_L2Lcmc ()

floatvips_col_L2Lcmc (float L);

Calculate Lcmc from L.

vips_col_C2Ccmc ()

floatvips_col_C2Ccmc (float C);

Calculate Ccmc from C.

vips_col_Ch2hcmc ()

floatvips_col_Ch2hcmc (float C,float h);

Calculate hcmc from C and h.

vips_col_make_tables_CMC ()

voidvips_col_make_tables_CMC (void);

Make the lookup tables for cmc.

vips_col_Lcmc2L ()

floatvips_col_Lcmc2L (float Lcmc);

Calculate L from Lcmc using a table. Callvips_col_make_tables_CMC() atleast once before using this function.

vips_col_Ccmc2C ()

floatvips_col_Ccmc2C (float Ccmc);

Calculate C from Ccmc using a table.Callvips_col_make_tables_CMC() atleast once before using this function.

vips_col_Chcmc2h ()

floatvips_col_Chcmc2h (float C,float hcmc);

Calculate h from C and hcmc, using a table.Callvips_col_make_tables_CMC() atleast once before using this function.

vips_col_sRGB2scRGB_8 ()

intvips_col_sRGB2scRGB_8 (int r,int g,int b,float *R,float *G,float *B);

vips_col_sRGB2scRGB_16 ()

intvips_col_sRGB2scRGB_16 (int r,int g,int b,float *R,float *G,float *B);

vips_col_sRGB2scRGB_8_noclip ()

intvips_col_sRGB2scRGB_8_noclip (int r,int g,int b,float *R,float *G,float *B);

vips_col_sRGB2scRGB_16_noclip ()

intvips_col_sRGB2scRGB_16_noclip (int r,int g,int b,float *R,float *G,float *B);

vips_col_scRGB2XYZ ()

intvips_col_scRGB2XYZ (float R,float G,float B,float *X,float *Y,float *Z);

Turn scRGB into XYZ.

See also:vips_scRGB2XYZ().

vips_col_XYZ2scRGB ()

intvips_col_XYZ2scRGB (float X,float Y,float Z,float *R,float *G,float *B);

Turn XYZ into scRGB.

See also:vips_XYZ2scRGB().

vips_col_scRGB2sRGB_8 ()

intvips_col_scRGB2sRGB_8 (float R,float G,float B,int *r,int *g,int *b,int *og);

vips_col_scRGB2sRGB_16 ()

intvips_col_scRGB2sRGB_16 (float R,float G,float B,int *r,int *g,int *b,int *og);

vips_col_scRGB2BW_16 ()

intvips_col_scRGB2BW_16 (float R,float G,float B,int *g,int *og);

vips_col_scRGB2BW_8 ()

intvips_col_scRGB2BW_8 (float R,float G,float B,int *g,int *og);

vips_pythagoras ()

floatvips_pythagoras (float L1,float a1,float b1,float L2,float a2,float b2);

Pythagorean distance between two points in colour space. Lab/XYZ/CMC etc.

vips_col_dE00 ()

floatvips_col_dE00 (float L1,float a1,float b1,float L2,float a2,float b2);

CIEDE2000, from:

Luo, Cui, Rigg, "The Development of the CIE 2000 Colour-DifferenceFormula: CIEDE2000", COLOR research and application, pp 340

VIPS_D93_X0

#define VIPS_D93_X0 (89.7400)

Areas under curves for D93, 2 degree observer.

VIPS_D93_Y0

#define VIPS_D93_Y0 (100.0)

VIPS_D93_Z0

#define VIPS_D93_Z0 (130.7700)

VIPS_D75_X0

#define VIPS_D75_X0 (94.9682)

Areas under curves for D75, 2 degree observer.

VIPS_D75_Y0

#define VIPS_D75_Y0 (100.0)

VIPS_D75_Z0

#define VIPS_D75_Z0 (122.5710)

VIPS_D65_X0

#define VIPS_D65_X0 (95.0470)

Areas under curves for D65, 2 degree observer.

VIPS_D65_Y0

#define VIPS_D65_Y0 (100.0)

VIPS_D65_Z0

#define VIPS_D65_Z0 (108.8827)

VIPS_D55_X0

#define VIPS_D55_X0 (95.6831)

Areas under curves for D55, 2 degree observer.

VIPS_D55_Y0

#define VIPS_D55_Y0 (100.0)

VIPS_D55_Z0

#define VIPS_D55_Z0 (92.0871)

VIPS_D50_X0

#define VIPS_D50_X0 (96.4250)

Areas under curves for D50, 2 degree observer.

VIPS_D50_Y0

#define VIPS_D50_Y0 (100.0)

VIPS_D50_Z0

#define VIPS_D50_Z0 (82.4680)

VIPS_A_X0

#define VIPS_A_X0 (109.8503)

Areas under curves for illuminant A (2856K), 2 degree observer.

VIPS_A_Y0

#define VIPS_A_Y0 (100.0)

VIPS_A_Z0

#define VIPS_A_Z0 (35.5849)

VIPS_B_X0

#define VIPS_B_X0 (99.0720)

Areas under curves for illuminant B (4874K), 2 degree observer.

VIPS_B_Y0

#define VIPS_B_Y0 (100.0)

VIPS_B_Z0

#define VIPS_B_Z0 (85.2230)

VIPS_C_X0

#define VIPS_C_X0 (98.0700)

Areas under curves for illuminant C (6774K), 2 degree observer.

VIPS_C_Y0

#define VIPS_C_Y0 (100.0)

VIPS_C_Z0

#define VIPS_C_Z0 (118.2300)

VIPS_E_X0

#define VIPS_E_X0 (100.0)

Areas under curves for equal energy illuminant E.

VIPS_E_Y0

#define VIPS_E_Y0 (100.0)

VIPS_E_Z0

#define VIPS_E_Z0 (100.0)

VIPS_D3250_X0

#define VIPS_D3250_X0 (105.6590)

Areas under curves for black body at 3250K, 2 degree observer.

VIPS_D3250_Y0

#define VIPS_D3250_Y0 (100.0)

VIPS_D3250_Z0

#define VIPS_D3250_Z0 (45.8501)

enum VipsIntent

The rendering intent.VIPS_INTENT_ABSOLUTE is best forscientific work,VIPS_INTENT_RELATIVE is usually best foraccurate communication with other imaging libraries.

enum VipsPCS

Pick a Profile Connection Space forvips_icc_import() andvips_icc_export(). LAB is usually best, XYZ can be more convenient in somecases.