blender(3)

1blender(1)               AfterStep X11 window manager               blender(1)
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NAME

6       blender -  functionality  for  blending  of image data using diofferent
7       algorithms libAfterImage/blender.h
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NAMEblender

DESCRIPTION

11       Defines implemented methods for ASScanline combining, that could
12       be passed to merge_layers() via ASImageLayer structure.
13       Also includes functions for colorspace conversion RGB<->HSV and
14       RGB<->HLS.
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AUTHOR

38       Sasha Vasko <sasha at aftercode dot net>
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NAMEcolorspace

DESCRIPTION

42       RGB colorspace: each color is represented as a combination of
43       red, green and blue values. Each value can be in 2 formats :
44       8 bit and 24.8 bit. 24.8 bit makes for 32bit value with lower 8 bits
45       used as a fraction for better calculation precision.
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47       HSV colorspace: each color is represented as a combination of
48       hue, saturation and value. Hue is generally colorizing component where
49       value represents brightness.
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51       HLS colorspace: each color is represented as a combination of
52       hue, luminance and saturation. It is analogous to HSV with value
53       substituted by luminance, except that luminance could be both
54       negative and positive.
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56       alpha channel could be added to any of the above colorspaces. alpha
57       channel is generally used to define transparentness of the color.
58       libAfterImage is using ARGB colorspace as a base colorspace, and
59       represents most colors as ARGB32 values or ASScanline scanlines of
60       pixels.
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NAMErgb2value()

63       rgb2saturation()
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65       rgb2hue()
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67       rgb2luminance()
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SYNOPSIS

72       CARD32 rgb2value( CARD32 red, CARD32 green, CARD32 blue );
73       CARD32 rgb2saturation( CARD32 red, CARD32 green, CARD32 blue );
74       CARD32 rgb2hue( CARD32 red, CARD32 green, CARD32 blue );
75       CARD32 rgb2luminance (CARD32 red, CARD32 green, CARD32 blue );
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INPUTS

78       red    - 32 bit value, 16 lower bits of which represent red channel
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80       green  - 32 bit value, 16 lower bits of which represent green channel
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82       blue   - 32 bit value, 16 lower bits of which represent blue channel
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RETURN VALUE

86       32 bit value, 16 lower bits of which represent value, saturation, hue,
87       or luminance respectively.
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DESCRIPTION

90       This functions translate RGB color into respective coordinates of
91       HSV and HLS colorspaces.
92       Returned hue values are in 16bit format. To translate it to and from
93       conventional 0-360 degree range, please use :
94       degrees2hue16() - converts conventional hue in 0-360 range into hue16
95       hue162degree()  - converts 16bit hue value into conventional degrees.
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NAMErgb2hsv()

98       rgb2hls()
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SYNOPSIS

103       CARD32 rgb2hsv( CARD32 red, CARD32 green, CARD32 blue,
104                       CARD32 *saturation, CARD32 *value );
105       CARD32 rgb2hls( CARD32 red, CARD32 green, CARD32 blue,
106                       CARD32 *luminance, CARD32 *saturation );
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INPUTS

109       red    - 32 bit value, 16 lower bits of which represent red channel
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111       green  - 32 bit value, 16 lower bits of which represent green channel
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113       blue   - 32 bit value, 16 lower bits of which represent blue channel
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RETURN VALUE

117       32 bit value, 16 lower bits of which represent hue.
118       32bit value pointed to by luminance, value and saturation will be set
119       respectively to color luminance, value and saturation.
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DESCRIPTION

122       This functions translate RGB color into full set of HSV and HLS
123       coordinates at once. These functions work faster then separate
124       translation into each channel.
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NAMEhsv2rgb()

127       hls2rgb()
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SYNOPSIS

132       void hsv2rgb( CARD32 hue, CARD32 saturation, CARD32 value,
133                     CARD32 *red, CARD32 *green, CARD32 *blue);
134       void hls2rgb( CARD32 hue, CARD32 luminance, CARD32 saturation,
135                     CARD32 *red, CARD32 *green, CARD32 *blue);
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INPUTS

138       hue    - 32 bit value, 16 lower bits of which represent hue.
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140       saturation
141              - 32 bit value, 16 lower bits of which represent saturation.
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143       value  - 32 bit value, 16 lower bits of which represent value.
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145       luminance
146              - 32 bit value, 16 lower bits of which represent luminance.
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RETURN VALUE

150       32bit value pointed to by red, green and blue will be set
151       respectively to RGB color channels.
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DESCRIPTION

154       This functions performs reverse translation from HSV and HSL to
155       RGB color
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NAMEalphablend_scanlines()

158       - combines top and bottom RGB components based on alpha channel  value:
159       bottom  =  bottom*(255-top_alpha)+top*top_alpha;  allanon_scanlines() -
160       averages each pixel between two scanlines. This method has  been  first
161       implemented  by  Ethan  Fisher  aka allanon as mode 130: bottom = (bot‐
162       tom+top)/2; tint_scanlines() - tints bottom scanline with top scanline(
163       with saturation to prevent overflow) : bottom = (bottom*(top/2))/32768;
164       add_scanlines() - adds top scanline to bottom scanline with  saturation
165       to  prevent overflow: bottom = bottom+top; sub_scanlines() - substrates
166       top scanline from bottom scanline with saturation to prevent  overflow:
167       bottom = bottom-top; diff_scanlines() - for each pixel calculates abso‐
168       lute difference between bottom and top color value  :  bottom  =  (bot‐
169       tom>top)?bottom-top:top-bottom;  darken_scanlines()  - substitutes each
170       pixel with minimum color value of top  and  bottom  :  bottom  =  (bot‐
171       tom>top)?top:bottom;  lighten_scanlines() - substitutes each pixel with
172       maximum color value of top and  bottom  :  bottom  =  (bottom>top)?bot‐
173       tom:top;  screen_scanlines()  - some wierd merging algorithm taken from
174       GIMP; overlay_scanlines() - some wierd  merging  algorithm  taken  from
175       GIMP;  hue_scanlines()  - substitute hue of bottom scanline with hue of
176       top scanline; saturate_scanlines() - substitute  saturation  of  bottom
177       scanline  with the saturation of top scanline; value_scanlines() - sub‐
178       stitute value of bottom scanline with the value of top  scanline;  col‐
179       orize_scanlines()  -  combine luminance of bottom scanline with hue and
180       saturation of top scanline; dissipate_scanlines()- randomly alpha-blend
181       bottom  and  top  scanlines,  using  alpha  value  of top scanline as a
182       threshold for random values.
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SYNOPSIS

186       void alphablend_scanlines( ASScanline *bottom, ASScanline *top, int );
187       void allanon_scanlines   ( ASScanline *bottom, ASScanline *top, int );
188       void tint_scanlines      ( ASScanline *bottom, ASScanline *top, int );
189       void add_scanlines       ( ASScanline *bottom, ASScanline *top, int );
190       void sub_scanlines       ( ASScanline *bottom, ASScanline *top, int );
191       void diff_scanlines      ( ASScanline *bottom, ASScanline *top, int );
192       void darken_scanlines    ( ASScanline *bottom, ASScanline *top, int );
193       void lighten_scanlines   ( ASScanline *bottom, ASScanline *top, int );
194       void screen_scanlines    ( ASScanline *bottom, ASScanline *top, int );
195       void overlay_scanlines   ( ASScanline *bottom, ASScanline *top, int );
196       void hue_scanlines       ( ASScanline *bottom, ASScanline *top, int );
197       void saturate_scanlines  ( ASScanline *bottom, ASScanline *top, int );
198       void value_scanlines     ( ASScanline *bottom, ASScanline *top, int );
199       void colorize_scanlines  ( ASScanline *bottom, ASScanline *top, int );
200       void dissipate_scanlines ( ASScanline *bottom, ASScanline *top, int );
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INPUTS

203       bottom - pointer to the ASScanline that will be overalayed
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205       top    - pointer to ASScanline that will overlay bottom.
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DESCRIPTION

209       This functions accept 2 scanlines as an arguments stored in
210       ASScanline structures with data in 24.8 format. Merging operation is
211       performed on these scanlines and result is stored in bottom
212       ASScanline.
213       The following are merging methods used in each function :
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NAMEblend_scanlines_name2func()

216       list_scanline_merging()
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SYNOPSIS

221       merge_scanlines_func blend_scanlines_name2func( const char *name );
222       void list_scanline_merging(FILE* stream, const char *format);
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INPUTS

225       name   - string, identifying scanline merging function.
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RETURN VALUE

229       returns pointer to the scanline merging function on succes.
230       NULL on failure.
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DESCRIPTION

233       blend_scanlines_name2func() will strip leading whitespaces off of
234       the supplied name, and then will attempt to match it against the list
235       of names of merging functions. It will then return pointer to the
236       function with matching name.
237       list_scanline_merging() simply prints out description of implemented
238       blending/merging methods onto the supplied stream, in supplied format.
239       Format must include 2 string specs, like so : "%s - %s" where first
240       one will be substituted to short method name, and second - description
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2443rd Berkeley Distribution      AfterStep v.2.2.6                    blender(1)