Provided by: libafterimage-dev_2.2.12-17.1build3_amd64 bug

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