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zero out edge tile buffers before tiff jpeg write 

see https://github.com/jcupitt/libvips/issues/204

thanks iwbh15
This commit is contained in:
John Cupitt 2014-12-10 09:41:31 +00:00
parent 9694cc8adb
commit 069ff8982c
1 changed files with 16 additions and 1 deletions
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17
libvips/foreign/vips2tiff.c
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@ -142,6 +142,8 @@
* - cache input in tile write mode to keep us sequential
* 3/12/14
* - embed XMP in output
* 10/12/14
* - zero out edge tile buffers before jpeg write, thanks iwbh15
*/
/*
@ -384,6 +386,18 @@ pack2tiff( TiffWrite *tw, VipsRegion *in, VipsPel *q, VipsRect *area )
{
int y;
/* JPEG compression can read outside the pixel area for edge tiles. It
* always compresses 8x8 blocks, so if the image width or height is
* not a multiple of 8, it can look beyond the pixels we will write.
*
* Black out the tile first to make sure these edge pixels are always
* zero.
*/
if( tw->compression == COMPRESSION_JPEG &&
(area->width < tw->tilew ||
area->height < tw->tileh) )
memset( q, 0, TIFFTileSize( tw->tif ) );
for( y = area->top; y < VIPS_RECT_BOTTOM( area ); y++ ) {
VipsPel *p = (VipsPel *) VIPS_REGION_ADDR( in, area->left, y );
@ -697,7 +711,8 @@ build_pyramid( TiffWrite *tw, PyramidLayer *above,
*/
*zap = layer;
if( layer->width > tw->tilew || layer->height > tw->tileh )
if( layer->width > tw->tilew ||
layer->height > tw->tileh )
if( build_pyramid( tw, layer,
&layer->below, layer->width, layer->height ) )
return( -1 );