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Use 254 pixels as default tile size 

I remember @benvanik, a friend and colleague, who worked on our DZI renderer (Seadragon) told us that, I believe, it’s better for GPUs to have power of two sized tiles, so 254px + 2 x 1px tile overlap will give you 256 pixel.s

> To keep my tiles nicely sized, I shrink in instead of expand out – that means my tiles are really 254×254 with a 1px border, so the images are 256x256px with 254×254 of useful imagery. If you wanted larger tiles, you’d go 510×510 with 1px border making 512×512 tiles.
> — Source: http://www.noxa.org/blog/2009/11/29/megatextures-in-webgl-2/
This commit is contained in:
Daniel Gasienica 2015-12-20 21:43:41 -08:00
parent 7267ca4a28
commit 09a30b602b
1 changed files with 7 additions and 7 deletions
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14
libvips/foreign/dzsave.c
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@ -116,9 +116,9 @@
Overlap handling
For deepzoom, tile-size == 256 and overlap == 1 means that edge tiles are
257 x 257 (though less at the bottom right) and non-edge tiles are 258 x
258. Tiles are positioned across the image in tile-size steps. This means
For deepzoom, tile-size == 254 and overlap == 1 means that edge tiles are
255 x 255 (though less at the bottom right) and non-edge tiles are 256 x
256. Tiles are positioned across the image in tile-size steps. This means
(confusingly) that two adjoining tiles will have two pixels in common.
This has caused bugs in the past.
@ -1938,7 +1938,7 @@ vips_foreign_save_dz_class_init( VipsForeignSaveDzClass *class )
_( "Tile size in pixels" ),
VIPS_ARGUMENT_OPTIONAL_INPUT,
G_STRUCT_OFFSET( VipsForeignSaveDz, tile_size ),
1, 8192, 256 );
1, 8192, 254 );
VIPS_ARG_ENUM( class, "depth", 13,
_( "Depth" ),
@ -1999,14 +1999,14 @@ vips_foreign_save_dz_class_init( VipsForeignSaveDzClass *class )
_( "Tile width in pixels" ),
VIPS_ARGUMENT_OPTIONAL_INPUT | VIPS_ARGUMENT_DEPRECATED,
G_STRUCT_OFFSET( VipsForeignSaveDz, tile_size ),
1, 8192, 256 );
1, 8192, 254 );
VIPS_ARG_INT( class, "tile_height", 12,
_( "Tile height" ),
_( "Tile height in pixels" ),
VIPS_ARGUMENT_OPTIONAL_INPUT | VIPS_ARGUMENT_DEPRECATED,
G_STRUCT_OFFSET( VipsForeignSaveDz, tile_size ),
1, 8192, 256 );
1, 8192, 254 );
}
@ -2016,7 +2016,7 @@ vips_foreign_save_dz_init( VipsForeignSaveDz *dz )
VIPS_SETSTR( dz->suffix, ".jpeg" );
dz->layout = VIPS_FOREIGN_DZ_LAYOUT_DZ;
dz->overlap = 1;
dz->tile_size = 256;
dz->tile_size = 254;
dz->tile_count = 0;
dz->depth = VIPS_FOREIGN_DZ_DEPTH_ONEPIXEL;
dz->angle = VIPS_ANGLE_D0;