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Leptonica 1.85.0
Image processing and image analysis suite
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Leptonica 1.85.0
Image processing and image analysis suite
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#include "allheaders.h"Go to the source code of this file.
Functions | |
| PIX * | pixColorGrayRegions (PIX *pixs, BOXA *boxa, l_int32 type, l_int32 thresh, l_int32 rval, l_int32 gval, l_int32 bval) |
| l_ok | pixColorGray (PIX *pixs, BOX *box, l_int32 type, l_int32 thresh, l_int32 rval, l_int32 gval, l_int32 bval) |
| PIX * | pixColorGrayMasked (PIX *pixs, PIX *pixm, l_int32 type, l_int32 thresh, l_int32 rval, l_int32 gval, l_int32 bval) |
| PIX * | pixSnapColor (PIX *pixd, PIX *pixs, l_uint32 srcval, l_uint32 dstval, l_int32 diff) |
| PIX * | pixSnapColorCmap (PIX *pixd, PIX *pixs, l_uint32 srcval, l_uint32 dstval, l_int32 diff) |
| PIX * | pixLinearMapToTargetColor (PIX *pixd, PIX *pixs, l_uint32 srcval, l_uint32 dstval) |
| l_ok | pixelLinearMapToTargetColor (l_uint32 scolor, l_uint32 srcmap, l_uint32 dstmap, l_uint32 *pdcolor) |
| PIX * | pixShiftByComponent (PIX *pixd, PIX *pixs, l_uint32 srcval, l_uint32 dstval) |
| l_ok | pixelShiftByComponent (l_int32 rval, l_int32 gval, l_int32 bval, l_uint32 srcval, l_uint32 dstval, l_uint32 *ppixel) |
| l_ok | pixelFractionalShift (l_int32 rval, l_int32 gval, l_int32 bval, l_float32 fract, l_uint32 *ppixel) |
| PIX * | pixMapWithInvariantHue (PIX *pixd, PIX *pixs, l_uint32 srcval, l_float32 fract) |
Coloring "gray" pixels
PIX *pixColorGrayRegions()
l_int32 pixColorGray()
PIX *pixColorGrayMasked()
Adjusting one or more colors to a target color
PIX *pixSnapColor()
PIX *pixSnapColorCmap()
Piecewise linear color mapping based on a source/target pair
PIX *pixLinearMapToTargetColor()
l_int32 pixelLinearMapToTargetColor()
Fractional shift of RGB towards black or white
PIX *pixShiftByComponent()
l_int32 pixelShiftByComponent()
l_int32 pixelFractionalShift()
PIX *pixShiftWithInvariantHue()
There are quite a few "coloring" functions in leptonica.
You can find them in these files:
coloring.c
paintcmap.c
pix2.c
blend.c
enhance.c
They fall into the following categories:
(1) Moving either the light or dark pixels toward a
specified color. (pixColorGray, pixColorGrayMasked)
(2) Forcing all pixels whose color is within some delta of a
specified color to move to that color. (pixSnapColor)
(3) Doing a piecewise linear color shift specified by a source
and a target color. Each component shifts independently.
(pixLinearMapToTargetColor, pixMapWithInvariantHue).
(4) Shifting all colors by a given fraction of their distance
from 0 (if shifting down) or from 255 (if shifting up).
This is useful for colorizing either the background or
the foreground of a grayscale image. (pixShiftByComponent)
(5) Shifting all colors by a component-dependent fraction of
their distance from 0 (if shifting down) or from 255 (if
shifting up). This is useful for modifying the color to
compensate for color shifts in acquisition or printing.
(enhance.c: pixColorShiftRGB, pixMosaicColorShiftRGB).
(6) Repainting selected pixels. (paintcmap.c: pixSetSelectMaskedCmap)
(7) Blending a fraction of a specific color with the existing RGB
color. (pix2.c: pixBlendInRect())
(8) Changing selected colors in a colormap.
(paintcmap.c: pixSetSelectCmap, pixSetSelectMaskedCmap)
(9) Shifting all the pixels towards black or white depending on
the gray value of a second image. (blend.c: pixFadeWithGray)
(10) Changing the hue, saturation or brightness, by changing one of
these parameters in HSV color space by a fraction of the distance
toward its end-point, but leaving the other two parameters
invariant. For example, you can change the brightness by moving
each pixel's v-parameter a specified fraction of the distance
toward 0 (darkening) or toward 255 (brightening), without altering
the hue or saturation. (enhance.c: pixModifySaturation,
pixModifyHue, pixModifyBrightness)
Definition in file coloring.c.
| l_ok pixColorGray | ( | PIX * | pixs, |
| BOX * | box, | ||
| l_int32 | type, | ||
| l_int32 | thresh, | ||
| l_int32 | rval, | ||
| l_int32 | gval, | ||
| l_int32 | bval ) |
| [in] | pixs | 8 bpp gray, rgb or colormapped image |
| [in] | box | [optional] region in which to apply color; can be NULL |
| [in] | type | L_PAINT_LIGHT, L_PAINT_DARK |
| [in] | thresh | average value below/above which pixel is unchanged |
| [in] | rval,gval,bval | new color to paint |
Notes:
(1) This is an in-place operation; pixs is modified.
If pixs is colormapped, the operation will add colors to the
colormap. Otherwise, pixs will be converted to 32 bpp rgb if
it is initially 8 bpp gray.
(2) If type == L_PAINT_LIGHT, it colorizes non-black pixels,
preserving antialiasing.
If type == L_PAINT_DARK, it colorizes non-white pixels,
preserving antialiasing.
(3) If box is NULL, applies function to the entire image; otherwise,
clips the operation to the intersection of the box and pix.
(4) If colormapped, calls pixColorGrayCmap(), which applies the
coloring algorithm only to pixels that are strictly gray.
(5) For RGB, determines a "gray" value by averaging; then uses this
value, plus the input rgb target, to generate the output
pixel values.
(6) thresh is only used for rgb; it is ignored for colormapped pix.
If type == L_PAINT_LIGHT, use thresh = 0 if all pixels are to
be colored (black pixels will be unaltered).
In situations where there are a lot of black pixels,
setting thresh > 0 will make the function considerably
more efficient without affecting the final result.
If type == L_PAINT_DARK, use thresh = 255 if all pixels
are to be colored (white pixels will be unaltered).
In situations where there are a lot of white pixels,
setting thresh < 255 will make the function considerably
more efficient without affecting the final result.
Definition at line 230 of file coloring.c.
References L_PAINT_DARK, and L_PAINT_LIGHT.
Referenced by pixColorGrayRegions().
| PIX * pixColorGrayMasked | ( | PIX * | pixs, |
| PIX * | pixm, | ||
| l_int32 | type, | ||
| l_int32 | thresh, | ||
| l_int32 | rval, | ||
| l_int32 | gval, | ||
| l_int32 | bval ) |
| [in] | pixs | 8 bpp gray, rgb or colormapped image |
| [in] | pixm | 1 bpp mask, through which to apply color |
| [in] | type | L_PAINT_LIGHT, L_PAINT_DARK |
| [in] | thresh | average value below/above which pixel is unchanged |
| [in] | rval,gval,bval | new color to paint |
Notes:
(1) This generates a new image, where some of the pixels under
FG in the mask are colorized.
(2) See pixColorGray() for usage with type and thresh. Note
that thresh is only used for rgb; it is ignored for
colormapped images. In most cases, the mask will be over
the darker parts and type == L_PAINT_DARK.
(3) If pixs is colormapped this calls pixColorMaskedCmap(),
which adds colors to the colormap for pixd; it only adds
colors corresponding to strictly gray colors in the colormap.
Otherwise, if pixs is 8 bpp gray, pixd will be 32 bpp rgb.
(4) If pixs is 32 bpp rgb, for each pixel a "gray" value is
found by averaging. This average is then used with the
input rgb target to generate the output pixel values.
(5) This can be used in conjunction with pixHasHighlightRed() to
add highlight color to a grayscale image.
Definition at line 354 of file coloring.c.
References GET_DATA_BIT, L_PAINT_DARK, and L_PAINT_LIGHT.
| PIX * pixColorGrayRegions | ( | PIX * | pixs, |
| BOXA * | boxa, | ||
| l_int32 | type, | ||
| l_int32 | thresh, | ||
| l_int32 | rval, | ||
| l_int32 | gval, | ||
| l_int32 | bval ) |
| [in] | pixs | 2, 4 or 8 bpp gray, rgb, or colormapped |
| [in] | boxa | of regions in which to apply color |
| [in] | type | L_PAINT_LIGHT, L_PAINT_DARK |
| [in] | thresh | average value below/above which pixel is unchanged |
| [in] | rval,gval,bval | new color to paint |
Notes:
(1) This generates a new image, where some of the pixels in each
box in the boxa are colorized. See pixColorGray() for usage
with type and thresh. Note that thresh is only used for
rgb; it is ignored for colormapped images.
(2) If the input image is colormapped, the new image will be 8 bpp
colormapped if possible; otherwise, it will be converted
to 32 bpp rgb. Only pixels that are strictly gray will be
colorized.
(3) If the input image is not colormapped, it is converted to rgb.
A "gray" value for a pixel is determined by averaging the
components, and the output rgb value is determined from this.
(4) This can be used in conjunction with pixHasHighlightRed() to
add highlight color to a grayscale image.
Definition at line 131 of file coloring.c.
References L_CLONE, L_PAINT_DARK, L_PAINT_LIGHT, and pixColorGray().
| l_ok pixelFractionalShift | ( | l_int32 | rval, |
| l_int32 | gval, | ||
| l_int32 | bval, | ||
| l_float32 | fract, | ||
| l_uint32 * | ppixel ) |
| [in] | rval | red source component |
| [in] | gval | green source component |
| [in] | bval | blue source component |
| [in] | fract | negative toward black; positive toward white |
| [out] | ppixel | resulting rgb value |
Notes:
(1) This linear transformation shifts each component a fraction
toward either black (fract < 0) or white (fract > 0).
(2) It changes the saturation and intensity, but leaves the hue
invariant. See usage in pixLinearMapToTargetColor() and
pixMapWithInvariantHue().
(3) fract is in the range [-1 .... +1]. If fract < 0,
saturation is increased and brightness is reduced. The
opposite results if fract > 0. If fract == -1,
the resulting pixel is black; fract == 1 results in white.
Definition at line 1013 of file coloring.c.
Referenced by pixMapWithInvariantHue().
| l_ok pixelLinearMapToTargetColor | ( | l_uint32 | scolor, |
| l_uint32 | srcmap, | ||
| l_uint32 | dstmap, | ||
| l_uint32 * | pdcolor ) |
| [in] | scolor | rgb source color: 0xrrggbb00 |
| [in] | srcmap | source mapping color: 0xrrggbb00 |
| [in] | dstmap | target mapping color: 0xrrggbb00 |
| [out] | pdcolor | rgb dest color: 0xrrggbb00 |
Notes:
(1) This does this does a piecewise linear mapping of each
component of scolor to dcolor, based on the relation
between the components of srcmap and dstmap. It is the
same transformation, performed on a single color, as mapped
on every pixel in a pix by pixLinearMapToTargetColor().
(2) For each component, if the sval is larger than the smap,
the dval will be pushed up from dmap towards white.
Otherwise, dval will be pushed down from dmap towards black.
This is because you can visualize the transformation as
a linear stretching where smap moves to dmap, and everything
else follows linearly with 0 and 255 fixed.
(3) The mapping will in general change the hue of scolor.
However, if the srcmap and dstmap targets are related by
a transformation given by pixelFractionalShift(), the hue
will be invariant.
Definition at line 770 of file coloring.c.
| l_ok pixelShiftByComponent | ( | l_int32 | rval, |
| l_int32 | gval, | ||
| l_int32 | bval, | ||
| l_uint32 | srcval, | ||
| l_uint32 | dstval, | ||
| l_uint32 * | ppixel ) |
| [in] | rval,gval,bval | |
| [in] | srcval | source color: 0xrrggbb00 |
| [in] | dstval | target color: 0xrrggbb00 |
| [out] | ppixel | rgb value |
Notes:
(1) This is a linear transformation that gives the same result
on a single pixel as pixShiftByComponent() gives
on a pix. Each component is handled separately. If
the dest component is larger than the src, then the
component is pushed toward 255 by the same fraction as
the src --> dest shift.
Definition at line 952 of file coloring.c.
| [in] | pixd | [optional]; either NULL or equal to pixs for in-place |
| [in] | pixs | 32 bpp rgb |
| [in] | srcval | source color: 0xrrggbb00 |
| [in] | dstval | target color: 0xrrggbb00 |
Notes:
(1) For each component (r, b, g) separately, this does a piecewise
linear mapping of the colors in pixs to colors in pixd.
If rs and rd are the red src and dest components in srcval and
dstval, then the range [0 ... rs] in pixs is mapped to
[0 ... rd] in pixd. Likewise, the range [rs ... 255] in pixs
is mapped to [rd ... 255] in pixd. And similarly for green
and blue.
(2) The mapping will in general change the hue of the pixels.
However, if the src and dst targets are related by
a transformation given by pixelFractionalShift(), the hue
is invariant. A special case is where the dest in the
map is white (255, 255, 255) for an arbitrary srcval.
(3) For inplace operation, call it this way:
pixLinearMapToTargetColor(pixs, pixs, ... );
For generating a new pixd:
pixd = pixLinearMapToTargetColor(NULL, pixs, ...);
(4) See pixShiftWithInvariantHue() for a special case of this function.
Definition at line 677 of file coloring.c.
Referenced by pixMapWithInvariantHue().
| [in] | pixd | [optional]; either NULL or equal to pixs for in-place |
| [in] | pixs | 32 bpp rgb |
| [in] | srcval | reference source color: 0xrrggbb00 |
| [in] | fract | fraction toward white of dest color |
Notes:
(1) The combination of srcval and fract define the linear
hue-preserving transformation, that is applied to all pixels.
(2) fract is in the range [-1 .... +1]. If fract < 0,
saturation is increased and brightness is reduced. The
opposite results if fract > 0. If fract == -1,
srcval is mapped to black; if fract == 1, it is mapped to white.
(3) For inplace operation, call it this way:
pixMapWithInvariatHue(pixs, pixs, ... );
For generating a new pixd:
pixd = pixMapWithInvariantHue(NULL, pixs, ...);
Definition at line 1062 of file coloring.c.
References pixelFractionalShift(), and pixLinearMapToTargetColor().
| [in] | pixd | [optional]; either NULL or equal to pixs for in-place |
| [in] | pixs | 32 bpp rgb, cmap OK |
| [in] | srcval | source color: 0xrrggbb00 |
| [in] | dstval | target color: 0xrrggbb00 |
Notes:
(1) For each component (r, b, g) separately, this does a linear
mapping of the colors in pixs to colors in pixd.
Let rs and rd be the red src and dest components in srcval and
dstval, and rval is the red component of the src pixel.
Then for all pixels in pixs, the mapping for the red
component from pixs to pixd is:
if (rd <= rs) (shift toward black)
rval --> (rd/rs) * rval
if (rd > rs) (shift toward white)
(255 - rval) --> ((255 - rs)/(255 - rd)) * (255 - rval)
Thus if rd <= rs, the red component of all pixels is
mapped by the same fraction toward white, and if rd > rs,
they are mapped by the same fraction toward black.
This is essentially a different linear TRC (gamma = 1)
for each component. The source and target color inputs are
just used to generate the three fractions.
(2) Note that this mapping differs from that in
pixLinearMapToTargetColor(), which maps rs --> rd and does
a piecewise stretching in between.
(3) For inplace operation, call it this way:
pixFractionalShiftByComponent(pixs, pixs, ... )
(4) For generating a new pixd:
pixd = pixLinearMapToTargetColor(NULL, pixs, ...)
(5) A simple application is to color a grayscale image.
A light background can be colored using srcval = 0xffffff00
and picking a target background color for dstval.
A dark foreground can be colored by using srcval = 0x0
and choosing a target foreground color for dstval.
Definition at line 853 of file coloring.c.
| [in] | pixd | [optional]; either NULL or equal to pixs for in-place |
| [in] | pixs | colormapped or 8 bpp gray or 32 bpp rgb |
| [in] | srcval | color center to be selected for change: 0xrrggbb00 |
| [in] | dstval | target color for pixels: 0xrrggbb00 |
| [in] | diff | max absolute difference, applied to all components |
Notes:
(1) For inplace operation, call it this way:
pixSnapColor(pixs, pixs, ... )
(2) For generating a new pixd:
pixd = pixSnapColor(NULL, pixs, ...)
(3) If pixs has a colormap, it is handled by pixSnapColorCmap().
(4) All pixels within 'diff' of 'srcval', componentwise,
will be changed to 'dstval'.
Definition at line 477 of file coloring.c.
References GET_DATA_BYTE, pixSnapColorCmap(), and SET_DATA_BYTE.
| [in] | pixd | [optional]; either NULL or equal to pixs for in-place |
| [in] | pixs | colormapped |
| [in] | srcval | color center to be selected for change: 0xrrggbb00 |
| [in] | dstval | target color for pixels: 0xrrggbb00 |
| [in] | diff | max absolute difference, applied to all components |
Notes:
(1) For inplace operation, call it this way:
pixSnapCcmap(pixs, pixs, ... )
(2) For generating a new pixd:
pixd = pixSnapCmap(NULL, pixs, ...)
(3) pixs must have a colormap.
(4) All colors within 'diff' of 'srcval', componentwise,
will be changed to 'dstval'.
Definition at line 562 of file coloring.c.
Referenced by pixSnapColor().
1.12.0