Provided by: libafterimage-dev_2.2.12-6_amd64 
NAME
blender - functionality for blending of image data using diofferent algorithms
libAfterImage/blender.h
NAMEblender
DESCRIPTION
Defines implemented methods for ASScanline combining, that could be passed to
merge_layers() via ASImageLayer structure. Also includes functions for colorspace
conversion RGB<->HSV and RGB<->HLS.
SEE ALSO
Functions :
Colorspace conversion :
rgb2value(), rgb2saturation(), rgb2hue(), rgb2luminance(),
rgb2hsv(), rgb2hls(), hsv2rgb(), hls2rgb().
merge_scanline methods :
alphablend_scanlines(), allanon_scanlines(),
tint_scanlines(), add_scanlines(), sub_scanlines(),
diff_scanlines(), darken_scanlines(), lighten_scanlines(),
screen_scanlines(), overlay_scanlines(), hue_scanlines(),
saturate_scanlines(), value_scanlines(),
colorize_scanlines(), dissipate_scanlines().
useful merging function name to function translator :
blend_scanlines_name2func()
Other libAfterImage modules :
ascmap.h asfont.h asimage.h asvisual.h blender.h export.h
import.h transform.h ximage.h
AUTHOR
Sasha Vasko <sasha at aftercode dot net>
libAfterImage/colorspace
NAMEcolorspace
DESCRIPTION
RGB colorspace: each color is represented as a combination of red, green and blue values.
Each value can be in 2 formats : 8 bit and 24.8 bit. 24.8 bit makes for 32bit value with
lower 8 bits used as a fraction for better calculation precision.
HSV colorspace: each color is represented as a combination of hue, saturation and value.
Hue is generally colorizing component where value represents brightness.
HLS colorspace: each color is represented as a combination of hue, luminance and
saturation. It is analogous to HSV with value substituted by luminance, except that
luminance could be both negative and positive.
alpha channel could be added to any of the above colorspaces. alpha channel is generally
used to define transparentness of the color. libAfterImage is using ARGB colorspace as a
base colorspace, and represents most colors as ARGB32 values or ASScanline scanlines of
pixels.
libAfterImage/rgb2value()
NAMErgb2value()
rgb2saturation()
rgb2hue()
rgb2luminance()
SYNOPSIS
CARD32 rgb2value( CARD32 red, CARD32 green, CARD32 blue ); CARD32 rgb2saturation( CARD32
red, CARD32 green, CARD32 blue ); CARD32 rgb2hue( CARD32 red, CARD32 green, CARD32 blue );
CARD32 rgb2luminance (CARD32 red, CARD32 green, CARD32 blue );
INPUTS
red - 32 bit value, 16 lower bits of which represent red channel
green - 32 bit value, 16 lower bits of which represent green channel
blue - 32 bit value, 16 lower bits of which represent blue channel
RETURN VALUE
32 bit value, 16 lower bits of which represent value, saturation, hue, or luminance
respectively.
DESCRIPTION
This functions translate RGB color into respective coordinates of HSV and HLS colorspaces.
Returned hue values are in 16bit format. To translate it to and from conventional 0-360
degree range, please use : degrees2hue16() - converts conventional hue in 0-360 range into
hue16 hue162degree() - converts 16bit hue value into conventional degrees.
libAfterImage/rgb2hsv()
NAMErgb2hsv()
rgb2hls()
SYNOPSIS
CARD32 rgb2hsv( CARD32 red, CARD32 green, CARD32 blue,
CARD32 *saturation, CARD32 *value ); CARD32 rgb2hls( CARD32 red, CARD32
green, CARD32 blue,
CARD32 *luminance, CARD32 *saturation );
INPUTS
red - 32 bit value, 16 lower bits of which represent red channel
green - 32 bit value, 16 lower bits of which represent green channel
blue - 32 bit value, 16 lower bits of which represent blue channel
RETURN VALUE
32 bit value, 16 lower bits of which represent hue. 32bit value pointed to by luminance,
value and saturation will be set respectively to color luminance, value and saturation.
DESCRIPTION
This functions translate RGB color into full set of HSV and HLS coordinates at once. These
functions work faster then separate translation into each channel.
libAfterImage/hsv2rgb()
NAMEhsv2rgb()
hls2rgb()
SYNOPSIS
void hsv2rgb( CARD32 hue, CARD32 saturation, CARD32 value,
CARD32 *red, CARD32 *green, CARD32 *blue); void hls2rgb( CARD32 hue, CARD32
luminance, CARD32 saturation,
CARD32 *red, CARD32 *green, CARD32 *blue);
INPUTS
hue - 32 bit value, 16 lower bits of which represent hue.
saturation
- 32 bit value, 16 lower bits of which represent saturation.
value - 32 bit value, 16 lower bits of which represent value.
luminance
- 32 bit value, 16 lower bits of which represent luminance.
RETURN VALUE
32bit value pointed to by red, green and blue will be set respectively to RGB color
channels.
DESCRIPTION
This functions performs reverse translation from HSV and HSL to RGB color
libAfterImage/merge_scanline
NAMEalphablend_scanlines()
- combines top and bottom RGB components based on alpha channel value: bottom =
bottom*(255-top_alpha)+top*top_alpha; allanon_scanlines() - averages each pixel between
two scanlines. This method has been first implemented by Ethan Fisher aka allanon as mode
130: bottom = (bottom+top)/2; tint_scanlines() - tints bottom scanline with top scanline(
with saturation to prevent overflow) : bottom = (bottom*(top/2))/32768; add_scanlines() -
adds top scanline to bottom scanline with saturation to prevent overflow: bottom =
bottom+top; sub_scanlines() - substrates top scanline from bottom scanline with saturation
to prevent overflow: bottom = bottom-top; diff_scanlines() - for each pixel calculates
absolute difference between bottom and top color value : bottom =
(bottom>top)?bottom-top:top-bottom; darken_scanlines() - substitutes each pixel with
minimum color value of top and bottom : bottom = (bottom>top)?top:bottom;
lighten_scanlines() - substitutes each pixel with maximum color value of top and bottom :
bottom = (bottom>top)?bottom:top; screen_scanlines() - some weird merging algorithm taken
from GIMP; overlay_scanlines() - some weird merging algorithm taken from GIMP;
hue_scanlines() - substitute hue of bottom scanline with hue of top scanline;
saturate_scanlines() - substitute saturation of bottom scanline with the saturation of top
scanline; value_scanlines() - substitute value of bottom scanline with the value of top
scanline; colorize_scanlines() - combine luminance of bottom scanline with hue and
saturation of top scanline; dissipate_scanlines()- randomly alpha-blend bottom and top
scanlines, using alpha value of top scanline as a threshold for random values.
SYNOPSIS
void alphablend_scanlines( ASScanline *bottom, ASScanline *top, int ); void
allanon_scanlines ( ASScanline *bottom, ASScanline *top, int ); void tint_scanlines
( ASScanline *bottom, ASScanline *top, int ); void add_scanlines ( ASScanline
*bottom, ASScanline *top, int ); void sub_scanlines ( ASScanline *bottom, ASScanline
*top, int ); void diff_scanlines ( ASScanline *bottom, ASScanline *top, int ); void
darken_scanlines ( ASScanline *bottom, ASScanline *top, int ); void lighten_scanlines
( ASScanline *bottom, ASScanline *top, int ); void screen_scanlines ( ASScanline
*bottom, ASScanline *top, int ); void overlay_scanlines ( ASScanline *bottom, ASScanline
*top, int ); void hue_scanlines ( ASScanline *bottom, ASScanline *top, int ); void
saturate_scanlines ( ASScanline *bottom, ASScanline *top, int ); void value_scanlines
( ASScanline *bottom, ASScanline *top, int ); void colorize_scanlines ( ASScanline
*bottom, ASScanline *top, int ); void dissipate_scanlines ( ASScanline *bottom, ASScanline
*top, int );
INPUTS
bottom - pointer to the ASScanline that will be overalayed
top - pointer to ASScanline that will overlay bottom.
DESCRIPTION
This functions accept 2 scanlines as an arguments stored in ASScanline structures with
data in 24.8 format. Merging operation is performed on these scanlines and result is
stored in bottom ASScanline. The following are merging methods used in each function :
libAfterImage/blend_scanlines_name2func()
NAMEblend_scanlines_name2func()
list_scanline_merging()
SYNOPSIS
merge_scanlines_func blend_scanlines_name2func( const char *name ); void
list_scanline_merging(FILE* stream, const char *format);
INPUTS
name - string, identifying scanline merging function.
RETURN VALUE
returns pointer to the scanline merging function on succes. NULL on failure.
DESCRIPTION
blend_scanlines_name2func() will strip leading whitespaces off of the supplied name, and
then will attempt to match it against the list of names of merging functions. It will then
return pointer to the function with matching name. list_scanline_merging() simply prints
out description of implemented blending/merging methods onto the supplied stream, in
supplied format. Format must include 2 string specs, like so : "%s - %s" where first one
will be substituted to short method name, and second - description