add new param to gifsave docs
also note in changelog and revise layout for 80 columns see https://github.com/libvips/libvips/pull/2628
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John Cupitt
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b0f993eec8
commit
3b6072437d
@ -13,6 +13,7 @@
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- add @unlimited to heifload [lovell]
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- edge antialiasing for mapim with @background, @extend and @premultiplied
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- add support for regions in C++ API [shado23]
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- add maxerror to gifsave [dloebl]
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26/11/21 started 8.12.3
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- better arg checking for hist_find_ndim [travisbell]
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@ -161,21 +161,24 @@ static int vips__cgif_write( void *target, const uint8_t *buffer,
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}
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/* Compare pixels in a lossy way (allow a slight colour difference).
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In combination with the GIF transparency optimization this leads to
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less difference between frames and therefore improves the compression ratio.
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* In combination with the GIF transparency optimization this leads to
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* less difference between frames and therefore improves the compression ratio.
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*/
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static gboolean
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cgif_pixels_are_equal(const VipsPel *cur, const VipsPel *bef, double maxerror)
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vips_foreign_save_cgif_pixels_are_equal( const VipsPel *cur, const VipsPel *bef,
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double maxerror )
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{
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if( bef[3] != 0xFF )
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/* Done. Cannot compare with alpha channel in frame before.
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/* Solid pixels only.
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*/
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return FALSE;
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/* Test Euclidean distance between the two points.
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*/
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const int dR = cur[0] - bef[0];
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const int dG = cur[1] - bef[1];
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const int dB = cur[2] - bef[2];
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return( sqrt( dR * dR + dG * dG + dB * dB ) <= maxerror );
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}
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@ -241,11 +244,13 @@ vips_foreign_save_cgif_write_frame( VipsForeignSaveCgif *cgif )
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* attach it as a local cmap when we write.
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*/
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if( cgif->quantisation_result )
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cgif->cgif_config.attrFlags |= CGIF_ATTR_NO_GLOBAL_TABLE;
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cgif->cgif_config.attrFlags |=
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CGIF_ATTR_NO_GLOBAL_TABLE;
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VIPS_FREEF( vips__quantise_result_destroy, cgif->quantisation_result );
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if( vips__quantise_image_quantize( cgif->input_image, cgif->attr,
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&cgif->quantisation_result ) ) {
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VIPS_FREEF( vips__quantise_result_destroy,
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cgif->quantisation_result );
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if( vips__quantise_image_quantize( cgif->input_image,
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cgif->attr, &cgif->quantisation_result ) ) {
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vips_error( class->nickname,
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"%s", _( "quantisation failed" ) );
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return( -1 );
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@ -258,15 +263,17 @@ vips_foreign_save_cgif_write_frame( VipsForeignSaveCgif *cgif )
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/* Dither frame.
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*/
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vips__quantise_set_dithering_level( cgif->quantisation_result, cgif->dither );
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vips__quantise_set_dithering_level( cgif->quantisation_result,
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cgif->dither );
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if( vips__quantise_write_remapped_image( cgif->quantisation_result,
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cgif->input_image, cgif->index, n_pels ) ) {
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vips_error( class->nickname, "%s", _( "dither failed" ) );
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return( -1 );
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}
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/* Call vips__quantise_get_palette() after vips__quantise_write_remapped_image(),
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* as palette is improved during remapping.
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/* Call vips__quantise_get_palette() after
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* vips__quantise_write_remapped_image(), as palette is improved
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* during remapping.
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*/
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cgif->lp = vips__quantise_get_palette( cgif->quantisation_result );
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rgb = cgif->palette_rgb;
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@ -331,7 +338,8 @@ vips_foreign_save_cgif_write_frame( VipsForeignSaveCgif *cgif )
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frame_config.transIndex = 0;
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}
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/* Do the transparency trick (only possible when no alpha channel present)
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/* Pixels which are equal to pixels in the previous frame can be made
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* transparent.
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*/
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if( cgif->frame_bytes_head ) {
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VipsPel *cur, *bef;
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@ -340,12 +348,12 @@ vips_foreign_save_cgif_write_frame( VipsForeignSaveCgif *cgif )
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bef = cgif->frame_bytes_head;
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if( !cgif->has_transparency ) {
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const uint8_t trans_index = cgif->lp->count;
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const double maxerror = cgif->maxerror;
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int i;
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for( i = 0; i < n_pels; i++ ) {
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if( cgif_pixels_are_equal( cur, bef, maxerror ) )
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if( vips_foreign_save_cgif_pixels_are_equal(
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cur, bef, cgif->maxerror ) )
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cgif->index[i] = trans_index;
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else {
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bef[0] = cur[0];
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@ -353,14 +361,18 @@ vips_foreign_save_cgif_write_frame( VipsForeignSaveCgif *cgif )
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bef[2] = cur[2];
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bef[3] = cur[3];
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}
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cur += 4;
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bef += 4;
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}
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frame_config.attrFlags |= CGIF_FRAME_ATTR_HAS_SET_TRANS;
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frame_config.attrFlags |=
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CGIF_FRAME_ATTR_HAS_SET_TRANS;
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frame_config.transIndex = trans_index;
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} else {
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/* Transparency trick not possible (alpha channel present).
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* Update head.
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}
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else {
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/* Transparency trick not possible (alpha channel
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* present). Update head.
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*/
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memcpy( bef, cur, 4 * n_pels);
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}
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@ -600,8 +612,8 @@ vips_foreign_save_cgif_class_init( VipsForeignSaveCgifClass *class )
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1, 8, 8 );
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VIPS_ARG_DOUBLE( class, "maxerror", 13,
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_( "Max. error for lossy transparency setting"),
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_( "Maximum pixel error to allow when identifying areas as identical (inter frame)" ),
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_( "Maximum error" ),
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_( "Maximum inter-frame error for transparency" ),
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VIPS_ARGUMENT_OPTIONAL_INPUT,
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G_STRUCT_OFFSET( VipsForeignSaveCgif, maxerror ),
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0, 32, 0.0 );
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@ -794,8 +806,9 @@ vips_foreign_save_cgif_buffer_init( VipsForeignSaveCgifBuffer *buffer )
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* * @dither: %gdouble, quantisation dithering level
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* * @effort: %gint, quantisation CPU effort
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* * @bitdepth: %gint, number of bits per pixel
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* * @maxerror: %gdouble, maximum inter-frame error for transparency
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*
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* Write a VIPS image to a file as GIF.
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* Write to a file in GIF format.
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*
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* Use @dither to set the degree of Floyd-Steinberg dithering
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* and @effort to control the CPU effort (1 is the fastest,
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@ -806,6 +819,10 @@ vips_foreign_save_cgif_buffer_init( VipsForeignSaveCgifBuffer *buffer )
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* always reserved for transparency. For example, a bitdepth of
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* 4 will allow the output to contain up to 15 colours.
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*
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* Use @maxerror to set the threshold below which pixels are considered equal.
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* Pixels which don't change from frame to frame can be made transparent,
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* improving the compression rate. Default 0.
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*
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* See also: vips_image_new_from_file().
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*
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* Returns: 0 on success, -1 on error.
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@ -835,6 +852,7 @@ vips_gifsave( VipsImage *in, const char *filename, ... )
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* * @dither: %gdouble, quantisation dithering level
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* * @effort: %gint, quantisation CPU effort
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* * @bitdepth: %gint, number of bits per pixel
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* * @maxerror: %gdouble, maximum inter-frame error for transparency
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*
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* As vips_gifsave(), but save to a memory buffer.
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*
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@ -885,6 +903,7 @@ vips_gifsave_buffer( VipsImage *in, void **buf, size_t *len, ... )
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* * @dither: %gdouble, quantisation dithering level
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* * @effort: %gint, quantisation CPU effort
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* * @bitdepth: %gint, number of bits per pixel
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* * @maxerror: %gdouble, maximum inter-frame error for transparency
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*
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* As vips_gifsave(), but save to a target.
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*
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