Leptonica  1.54
Файл src/colorspace.c
#include <string.h>
#include <math.h>
#include "allheaders.h"

Макросы

#define DEBUG_HISTO   0
#define SLOW_CUBE_ROOT   0

Функции

static l_float32 lab_forward (l_float32 v)
static l_float32 lab_reverse (l_float32 v)
PIXpixConvertRGBToHSV (PIX *pixd, PIX *pixs)
PIXpixConvertHSVToRGB (PIX *pixd, PIX *pixs)
l_int32 convertRGBToHSV (l_int32 rval, l_int32 gval, l_int32 bval, l_int32 *phval, l_int32 *psval, l_int32 *pvval)
l_int32 convertHSVToRGB (l_int32 hval, l_int32 sval, l_int32 vval, l_int32 *prval, l_int32 *pgval, l_int32 *pbval)
l_int32 pixcmapConvertRGBToHSV (PIXCMAP *cmap)
l_int32 pixcmapConvertHSVToRGB (PIXCMAP *cmap)
PIXpixConvertRGBToHue (PIX *pixs)
PIXpixConvertRGBToSaturation (PIX *pixs)
PIXpixConvertRGBToValue (PIX *pixs)
PIXpixMakeRangeMaskHS (PIX *pixs, l_int32 huecenter, l_int32 huehw, l_int32 satcenter, l_int32 sathw, l_int32 regionflag)
PIXpixMakeRangeMaskHV (PIX *pixs, l_int32 huecenter, l_int32 huehw, l_int32 valcenter, l_int32 valhw, l_int32 regionflag)
PIXpixMakeRangeMaskSV (PIX *pixs, l_int32 satcenter, l_int32 sathw, l_int32 valcenter, l_int32 valhw, l_int32 regionflag)
PIXpixMakeHistoHS (PIX *pixs, l_int32 factor, NUMA **pnahue, NUMA **pnasat)
PIXpixMakeHistoHV (PIX *pixs, l_int32 factor, NUMA **pnahue, NUMA **pnaval)
PIXpixMakeHistoSV (PIX *pixs, l_int32 factor, NUMA **pnasat, NUMA **pnaval)
l_int32 pixFindHistoPeaksHSV (PIX *pixs, l_int32 type, l_int32 width, l_int32 height, l_int32 npeaks, l_float32 erasefactor, PTA **ppta, NUMA **pnatot, PIXA **ppixa)
PIXdisplayHSVColorRange (l_int32 hval, l_int32 sval, l_int32 vval, l_int32 huehw, l_int32 sathw, l_int32 nsamp, l_int32 factor)
PIXpixConvertRGBToYUV (PIX *pixd, PIX *pixs)
PIXpixConvertYUVToRGB (PIX *pixd, PIX *pixs)
l_int32 convertRGBToYUV (l_int32 rval, l_int32 gval, l_int32 bval, l_int32 *pyval, l_int32 *puval, l_int32 *pvval)
l_int32 convertYUVToRGB (l_int32 yval, l_int32 uval, l_int32 vval, l_int32 *prval, l_int32 *pgval, l_int32 *pbval)
l_int32 pixcmapConvertRGBToYUV (PIXCMAP *cmap)
l_int32 pixcmapConvertYUVToRGB (PIXCMAP *cmap)
FPIXApixConvertRGBToXYZ (PIX *pixs)
PIXfpixaConvertXYZToRGB (FPIXA *fpixa)
l_int32 convertRGBToXYZ (l_int32 rval, l_int32 gval, l_int32 bval, l_float32 *pfxval, l_float32 *pfyval, l_float32 *pfzval)
l_int32 convertXYZToRGB (l_float32 fxval, l_float32 fyval, l_float32 fzval, l_int32 blackout, l_int32 *prval, l_int32 *pgval, l_int32 *pbval)
FPIXAfpixaConvertXYZToLAB (FPIXA *fpixas)
FPIXAfpixaConvertLABToXYZ (FPIXA *fpixas)
l_int32 convertXYZToLAB (l_float32 xval, l_float32 yval, l_float32 zval, l_float32 *plval, l_float32 *paval, l_float32 *pbval)
l_int32 convertLABToXYZ (l_float32 lval, l_float32 aval, l_float32 bval, l_float32 *pxval, l_float32 *pyval, l_float32 *pzval)
FPIXApixConvertRGBToLAB (PIX *pixs)
PIXfpixaConvertLABToRGB (FPIXA *fpixa)
l_int32 convertRGBToLAB (l_int32 rval, l_int32 gval, l_int32 bval, l_float32 *pflval, l_float32 *pfaval, l_float32 *pfbval)
l_int32 convertLABToRGB (l_float32 flval, l_float32 faval, l_float32 fbval, l_int32 *prval, l_int32 *pgval, l_int32 *pbval)

Макросы

#define DEBUG_HISTO   0
#define SLOW_CUBE_ROOT   0

Функции

l_int32 convertHSVToRGB ( l_int32  hval,
l_int32  sval,
l_int32  vval,
l_int32 prval,
l_int32 pgval,
l_int32 pbval 
)

convertHSVToRGB()

Input: hval, sval, vval &rval, &gval, &bval (<return> RGB values) Return: 0 if OK, 1 on error

Notes: (1) See convertRGBToHSV() for valid input range of HSV values and their interpretation in color space.

l_int32 convertLABToRGB ( l_float32  flval,
l_float32  faval,
l_float32  fbval,
l_int32 prval,
l_int32 pgval,
l_int32 pbval 
)

convertLABToRGB()

Input: flval, faval, fbval &rval, &gval, &bval (<return> rgb values) Return: 0 if OK, 1 on error

Notes: (1) For values of lab that are out of gamut for rgb, the rgb components are set to the closest valid color.

l_int32 convertLABToXYZ ( l_float32  lval,
l_float32  aval,
l_float32  bval,
l_float32 pxval,
l_float32 pyval,
l_float32 pzval 
)

convertLABToXYZ()

Input: lval, aval, bval &xval, &yval, &zval (<return> xyz values) Return: 0 if OK, 1 on error

l_int32 convertRGBToHSV ( l_int32  rval,
l_int32  gval,
l_int32  bval,
l_int32 phval,
l_int32 psval,
l_int32 pvval 
)

convertRGBToHSV()

Input: rval, gval, bval (RGB input) &hval, &sval, &vval (<return> HSV values) Return: 0 if OK, 1 on error

Notes: (1) The range of returned values is: h [0 ... 239] s [0 ... 255] v [0 ... 255] (2) If r = g = b, the pixel is gray (s = 0), and we define h = 0. (3) h wraps around, so that h = 0 and h = 240 are equivalent in hue space. (4) h has the following correspondence to color: h = 0 magenta h = 40 red h = 80 yellow h = 120 green h = 160 cyan h = 200 blue

l_int32 convertRGBToLAB ( l_int32  rval,
l_int32  gval,
l_int32  bval,
l_float32 pflval,
l_float32 pfaval,
l_float32 pfbval 
)

convertRGBToLAB()

Input: rval, gval, bval (rgb input) &flval, &faval, &fbval (<return> lab values) Return: 0 if OK, 1 on error

Notes: (1) These conversions are for illuminant D65 acting on linear sRGB values.

l_int32 convertRGBToXYZ ( l_int32  rval,
l_int32  gval,
l_int32  bval,
l_float32 pfxval,
l_float32 pfyval,
l_float32 pfzval 
)

convertRGBToXYZ()

Input: rval, gval, bval (rgb input) &fxval, &fyval, &fzval (<return> xyz values) Return: 0 if OK, 1 on error

Notes: (1) These conversions are for illuminant D65 acting on linear sRGB values.

l_int32 convertRGBToYUV ( l_int32  rval,
l_int32  gval,
l_int32  bval,
l_int32 pyval,
l_int32 puval,
l_int32 pvval 
)

convertRGBToYUV()

Input: rval, gval, bval (RGB input) &yval, &uval, &vval (<return> YUV values) Return: 0 if OK, 1 on error

Notes: (1) The range of returned values is: Y [16 ... 235] U [16 ... 240] V [16 ... 240]

l_int32 convertXYZToLAB ( l_float32  xval,
l_float32  yval,
l_float32  zval,
l_float32 plval,
l_float32 paval,
l_float32 pbval 
)

convertXYZToLAB()

Input: xval, yval, zval (xyz input) &lval, &aval, &bval (<return> lab values) Return: 0 if OK, 1 on error

l_int32 convertXYZToRGB ( l_float32  fxval,
l_float32  fyval,
l_float32  fzval,
l_int32  blackout,
l_int32 prval,
l_int32 pgval,
l_int32 pbval 
)

convertXYZToRGB()

Input: fxval, fyval, fzval blackout (0 to output nearest color if out of gamut; 1 to output black) &rval, &gval, &bval (<return> rgb values) Return: 0 if OK, 1 on error

Notes: (1) For values of xyz that are out of gamut for rgb, at least one of the r, g or b components will be either less than 0 or greater than 255. For that situation: * if blackout == 0, the individual component(s) that are out of gamut will be set to 0 or 255, respectively. * if blackout == 1, the output color will be set to black

l_int32 convertYUVToRGB ( l_int32  yval,
l_int32  uval,
l_int32  vval,
l_int32 prval,
l_int32 pgval,
l_int32 pbval 
)

convertYUVToRGB()

Input: yval, uval, vval &rval, &gval, &bval (<return> RGB values) Return: 0 if OK, 1 on error

Notes: (1) The range of valid input values is: Y [16 ... 235] U [16 ... 240] V [16 ... 240] (2) Conversion of RGB --> YUV --> RGB leaves the image unchanged. (3) The YUV gamut is larger than the RBG gamut; many YUV values will result in an invalid RGB value. We clip individual r,g,b components to the range [0, 255], and do not test input.

PIX* displayHSVColorRange ( l_int32  hval,
l_int32  sval,
l_int32  vval,
l_int32  huehw,
l_int32  sathw,
l_int32  nsamp,
l_int32  factor 
)

displayHSVColorRange()

Input: hval (hue center value; in range [0 ... 240] sval (saturation center value; in range [0 ... 255] vval (max intensity value; in range [0 ... 255] huehw (half-width of hue range; > 0) sathw (half-width of saturation range; > 0) nsamp (number of samplings in each half-width in hue and sat) factor (linear size of each color square, in pixels; > 3) Return: pixd (32 bpp set of color squares over input range), or null on error

Notes: (1) The total number of color samplings in each of the hue and saturation directions is 2 * nsamp + 1.

fpixaConvertLABToRGB()

Input: fpixa (three fpix: l,a,b) Return: pixd (rgb)

Notes: (1) The lab image is stored in three fpix.

fpixaConvertLABToXYZ()

Input: fpixa (lab) Return: fpixa (xyz)

Notes: (1) The input [l,a,b] and output [x,y,z] values are stored as float values, each set in three fpix.

fpixaConvertXYZToLAB()

Input: fpixa (xyz) Return: fpixa (lab)

Notes: (1) The input [x,y,z] and output [l,a,b] values are stored as float values, each set in three fpix. (2) The CIE LAB color space was invented in 1976, as an absolute reference for specifying colors that we can perceive, independently of the rendering device. It was invented to align color display and print images. For information, see: http://www.brucelindbloom.com/ http://en.wikipedia.org/wiki/Lab_color_space

fpixaConvertXYZToRGB()

Input: fpixa (three fpix: x,y,z) Return: pixd (rgb)

Notes: (1) The xyz image is stored in three fpix. (2) For values of xyz that are out of gamut for rgb, the rgb components are set to the closest valid color.

static l_float32 lab_forward ( l_float32  v) [static]
static l_float32 lab_reverse ( l_float32  v) [static]

pixcmapConvertHSVToRGB()

Input: colormap Return: 0 if OK; 1 on error

Notes:

  • in-place transform
  • See convertRGBToHSV() for def'n of HSV space.
  • replaces: h --> r, s --> g, v --> b

pixcmapConvertRGBToHSV()

Input: colormap Return: 0 if OK; 1 on error

Notes:

  • in-place transform
  • See convertRGBToHSV() for def'n of HSV space.
  • replaces: r --> h, g --> s, b --> v

pixcmapConvertRGBToYUV()

Input: colormap Return: 0 if OK; 1 on error

Notes:

  • in-place transform
  • See convertRGBToYUV() for def'n of YUV space.
  • replaces: r --> y, g --> u, b --> v

pixcmapConvertYUVToRGB()

Input: colormap Return: 0 if OK; 1 on error

Notes:

  • in-place transform
  • See convertRGBToYUV() for def'n of YUV space.
  • replaces: y --> r, u --> g, v --> b
PIX* pixConvertHSVToRGB ( PIX pixd,
PIX pixs 
)

pixConvertHSVToRGB()

Input: pixd (can be NULL; if not NULL, must == pixs) pixs Return: pixd always

Notes: (1) For pixs = pixd, this is in-place; otherwise pixd must be NULL. (2) The user takes responsibility for making sure that pixs is in our HSV space. The definition of our HSV space is given in convertRGBToHSV(). (3) The h, s and v values are stored in the same places as the r, g and b values, respectively. Here, they are explicitly placed in the 3 MS bytes in the pixel.

PIX* pixConvertRGBToHSV ( PIX pixd,
PIX pixs 
)

pixConvertRGBToHSV()

Input: pixd (can be NULL; if not NULL, must == pixs) pixs Return: pixd always

Notes: (1) For pixs = pixd, this is in-place; otherwise pixd must be NULL. (2) The definition of our HSV space is given in convertRGBToHSV(). (3) The h, s and v values are stored in the same places as the r, g and b values, respectively. Here, they are explicitly placed in the 3 MS bytes in the pixel. (4) Normalizing to 1 and considering the r,g,b components, a simple way to understand the HSV space is:

  • v = max(r,g,b)
  • s = (max - min) / max
  • h ~ (mid - min) / (max - min) [apart from signs and constants] (5) Normalizing to 1, some properties of the HSV space are:
  • For gray values (r = g = b) along the continuum between black and white: s = 0 (becoming undefined as you approach black) h is undefined everywhere
  • Where one component is saturated and the others are zero: v = 1 s = 1 h = 0 (r = max), 1/3 (g = max), 2/3 (b = max)
  • Where two components are saturated and the other is zero: v = 1 s = 1 h = 1/2 (if r = 0), 5/6 (if g = 0), 1/6 (if b = 0)
PIX* pixConvertRGBToHue ( PIX pixs)

pixConvertRGBToHue()

Input: pixs (32 bpp RGB or 8 bpp with colormap) Return: pixd (8 bpp hue of HSV), or null on error

Notes: (1) The conversion to HSV hue is in-lined here. (2) If there is a colormap, it is removed. (3) If you just want the hue component, this does it at about 10 Mpixels/sec/GHz, which is about 2x faster than using pixConvertRGBToHSV()

pixConvertRGBToLAB()

Input: pixs (rgb) Return: fpixa (lab)

Notes: (1) The [l,a,b] values are stored as float values in three fpix that are returned in a fpixa.

pixConvertRGBToSaturation()

Input: pixs (32 bpp RGB or 8 bpp with colormap) Return: pixd (8 bpp sat of HSV), or null on error

Notes: (1) The conversion to HSV sat is in-lined here. (2) If there is a colormap, it is removed. (3) If you just want the saturation component, this does it at about 12 Mpixels/sec/GHz.

pixConvertRGBToValue()

Input: pixs (32 bpp RGB or 8 bpp with colormap) Return: pixd (8 bpp max component intensity of HSV), or null on error

Notes: (1) The conversion to HSV sat is in-lined here. (2) If there is a colormap, it is removed. (3) If you just want the value component, this does it at about 35 Mpixels/sec/GHz.

pixConvertRGBToXYZ()

Input: pixs (rgb) Return: fpixa (xyz)

Notes: (1) The [x,y,z] values are stored as float values in three fpix that are returned in a fpixa. (2) The XYZ color space was defined in 1931 as a reference model that simulates human color perception. When Y is taken as luminance, the values of X and Z constitute a color plane representing all the hues that can be perceived. This gamut of colors is larger than the gamuts that can be displayed or printed. For example, although all rgb values map to XYZ, the converse is not true. (3) The value of the coefficients depends on the illuminant. We use coefficients for converting sRGB under D65 (the spectrum from a 6500 degree K black body; an approximation to daylight color). See, e.g., http://www.cs.rit.edu/~ncs/color/t_convert.html For more general information on color transforms, see: http://www.brucelindbloom.com/ http://user.engineering.uiowa.edu/~aip/Misc/ColorFAQ.html http://en.wikipedia.org/wiki/CIE_1931_color_space

PIX* pixConvertRGBToYUV ( PIX pixd,
PIX pixs 
)

pixConvertRGBToYUV()

Input: pixd (can be NULL; if not NULL, must == pixs) pixs Return: pixd always

Notes: (1) For pixs = pixd, this is in-place; otherwise pixd must be NULL. (2) The Y, U and V values are stored in the same places as the r, g and b values, respectively. Here, they are explicitly placed in the 3 MS bytes in the pixel. (3) Normalizing to 1 and considering the r,g,b components, a simple way to understand the YUV space is:

  • Y = weighted sum of (r,g,b)
  • U = weighted difference between Y and B
  • V = weighted difference between Y and R (4) Following video conventions, Y, U and V are in the range: Y: [16, 235] U: [16, 240] V: [16, 240] (5) For the coefficients in the transform matrices, see eq. 4 in "Frequently Asked Questions about Color" by Charles Poynton, //http://user.engineering.uiowa.edu/~aip/Misc/ColorFAQ.html
PIX* pixConvertYUVToRGB ( PIX pixd,
PIX pixs 
)

pixConvertYUVToRGB()

Input: pixd (can be NULL; if not NULL, must == pixs) pixs Return: pixd always

Notes: (1) For pixs = pixd, this is in-place; otherwise pixd must be NULL. (2) The user takes responsibility for making sure that pixs is in YUV space. (3) The Y, U and V values are stored in the same places as the r, g and b values, respectively. Here, they are explicitly placed in the 3 MS bytes in the pixel.

l_int32 pixFindHistoPeaksHSV ( PIX pixs,
l_int32  type,
l_int32  width,
l_int32  height,
l_int32  npeaks,
l_float32  erasefactor,
PTA **  ppta,
NUMA **  pnatot,
PIXA **  ppixa 
)

pixFindHistoPeaksHSV()

Input: pixs (32 bpp; HS, HV or SV histogram; not changed) type (L_HS_HISTO, L_HV_HISTO or L_SV_HISTO) width (half width of sliding window) height (half height of sliding window) npeaks (number of peaks to look for) erasefactor (ratio of erase window size to sliding window size) &pta (<return> locations of max for each integrated peak area) &natot (<return> integrated peak areas) &pixa (<optional return>=""> pixa for debugging; NULL to skip) Return: 0 if OK, 1 on error

Notes: (1) pixs is a 32 bpp histogram in a pair of HSV colorspace. It should be thought of as a single sample with 32 bps (bits/sample). (2) After each peak is found, the peak is erased with a window that is centered on the peak and scaled from the sliding window by . Typically, is chosen to be > 1.0. (3) Data for a maximum of is returned in and . (4) For debugging, after the pixa is returned, display with: pixd = pixaDisplayTiledInRows(pixa, 32, 1000, 1.0, 0, 30, 2);

PIX* pixMakeHistoHS ( PIX pixs,
l_int32  factor,
NUMA **  pnahue,
NUMA **  pnasat 
)

pixMakeHistoHS()

Input: pixs (HSV colorspace) factor (subsampling factor; integer) &nahue (<optional return>=""> hue histogram) &nasat (<optional return>=""> saturation histogram) Return: pixd (32 bpp histogram in hue and saturation), or null on error

Notes: (1) pixs is a 32 bpp image in HSV colorspace; hue is in the "red" byte, saturation is in the "green" byte. (2) In pixd, hue is displayed vertically; saturation horizontally. The dimensions of pixd are w = 256, h = 240, and the depth is 32 bpp. The value at each point is simply the number of pixels found at that value of hue and saturation.

PIX* pixMakeHistoHV ( PIX pixs,
l_int32  factor,
NUMA **  pnahue,
NUMA **  pnaval 
)

pixMakeHistoHV()

Input: pixs (HSV colorspace) factor (subsampling factor; integer) &nahue (<optional return>=""> hue histogram) &naval (<optional return>=""> max intensity (value) histogram) Return: pixd (32 bpp histogram in hue and value), or null on error

Notes: (1) pixs is a 32 bpp image in HSV colorspace; hue is in the "red" byte, max intensity ("value") is in the "blue" byte. (2) In pixd, hue is displayed vertically; intensity horizontally. The dimensions of pixd are w = 256, h = 240, and the depth is 32 bpp. The value at each point is simply the number of pixels found at that value of hue and intensity.

PIX* pixMakeHistoSV ( PIX pixs,
l_int32  factor,
NUMA **  pnasat,
NUMA **  pnaval 
)

pixMakeHistoSV()

Input: pixs (HSV colorspace) factor (subsampling factor; integer) &nasat (<optional return>=""> sat histogram) &naval (<optional return>=""> max intensity (value) histogram) Return: pixd (32 bpp histogram in sat and value), or null on error

Notes: (1) pixs is a 32 bpp image in HSV colorspace; sat is in the "green" byte, max intensity ("value") is in the "blue" byte. (2) In pixd, sat is displayed vertically; intensity horizontally. The dimensions of pixd are w = 256, h = 256, and the depth is 32 bpp. The value at each point is simply the number of pixels found at that value of saturation and intensity.

PIX* pixMakeRangeMaskHS ( PIX pixs,
l_int32  huecenter,
l_int32  huehw,
l_int32  satcenter,
l_int32  sathw,
l_int32  regionflag 
)

pixMakeRangeMaskHS()

Input: pixs (32 bpp rgb) huecenter (center value of hue range) huehw (half-width of hue range) satcenter (center value of saturation range) sathw (half-width of saturation range) regionflag (L_INCLUDE_REGION, L_EXCLUDE_REGION) Return: pixd (1 bpp mask over selected pixels), or null on error

Notes: (1) The pixels are selected based on the specified ranges of hue and saturation. For selection or exclusion, the pixel HS component values must be within both ranges. Care must be taken in finding the hue range because of wrap-around. (2) Use == L_INCLUDE_REGION to take only those pixels within the rectangular region specified in HS space. Use == L_EXCLUDE_REGION to take all pixels except those within the rectangular region specified in HS space.

PIX* pixMakeRangeMaskHV ( PIX pixs,
l_int32  huecenter,
l_int32  huehw,
l_int32  valcenter,
l_int32  valhw,
l_int32  regionflag 
)

pixMakeRangeMaskHV()

Input: pixs (32 bpp rgb) huecenter (center value of hue range) huehw (half-width of hue range) valcenter (center value of max intensity range) valhw (half-width of max intensity range) regionflag (L_INCLUDE_REGION, L_EXCLUDE_REGION) Return: pixd (1 bpp mask over selected pixels), or null on error

Notes: (1) The pixels are selected based on the specified ranges of hue and max intensity values. For selection or exclusion, the pixel HV component values must be within both ranges. Care must be taken in finding the hue range because of wrap-around. (2) Use == L_INCLUDE_REGION to take only those pixels within the rectangular region specified in HV space. Use == L_EXCLUDE_REGION to take all pixels except those within the rectangular region specified in HV space.

PIX* pixMakeRangeMaskSV ( PIX pixs,
l_int32  satcenter,
l_int32  sathw,
l_int32  valcenter,
l_int32  valhw,
l_int32  regionflag 
)

pixMakeRangeMaskSV()

Input: pixs (32 bpp rgb) satcenter (center value of saturation range) sathw (half-width of saturation range) valcenter (center value of max intensity range) valhw (half-width of max intensity range) regionflag (L_INCLUDE_REGION, L_EXCLUDE_REGION) Return: pixd (1 bpp mask over selected pixels), or null on error

Notes: (1) The pixels are selected based on the specified ranges of saturation and max intensity (val). For selection or exclusion, the pixel SV component values must be within both ranges. (2) Use == L_INCLUDE_REGION to take only those pixels within the rectangular region specified in SV space. Use == L_EXCLUDE_REGION to take all pixels except those within the rectangular region specified in SV space.