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add n-bit palette tiff read 

The tiff reader can do 1, 2, 4, 8 bits per sample palette read.
Greyscale palette images always come out as colour, I'm not sure how to
fix this. Perhaps I have to search the palette and see if r==g==b?
This commit is contained in:
John Cupitt 2011-04-21 09:53:02 +01:00
parent b275f1dd26
commit f13bf34ce3
2 changed files with 55 additions and 31 deletions
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1
ChangeLog
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@ -50,6 +50,7 @@
- removed the links feature, won't work with vips8
- got rid of the tools/ subdirs
- added im_bufjpeg2vips()
- tiff reader can do 1, 2, 4, 8 bit palette images
30/11/10 started 7.24.0
- bump for new stable

85
libvips/format/im_tiff2vips.c
View File

@ -119,6 +119,8 @@
* into the output region, or writeline directly from the tiff buffer
* 4/4/11
* - argh int/uint mixup for rows_per_strip, thanks Bubba
* 21/4/11
* - palette read can do 1,2,4,8 bits per sample
*/
/*
@ -592,52 +594,76 @@ parse_greyscale32f( ReadTiff *rtiff, int pm, IMAGE *out )
return( 0 );
}
typedef struct {
/* LUTs mapping image indexes to RGB.
*/
PEL *red;
PEL *green;
PEL *blue;
/* Bits per sample.
*/
int bps;
} PaletteRead;
/* Per-scanline process function for palette images.
*/
static void
palette_line( PEL *q, PEL *p, int n, void *flg )
{
/* Extract maps.
*/
PEL *red = ((PEL **) flg)[0];
PEL *green = ((PEL **) flg)[1];
PEL *blue = ((PEL **) flg)[2];
PaletteRead *read = (PaletteRead *) flg;
int bit;
PEL data;
int x;
/* Read bytes, generating colour.
*/
bit = 0;
data = 0;
for( x = 0; x < n; x++ ) {
int i = *p++;
int i;
q[0] = red[i];
q[1] = green[i];
q[2] = blue[i];
if( bit <= 0 ) {
data = *p++;
bit = 8;
}
i = data >> (8 - read->bps);
data <<= read->bps;
bit -= read->bps;
q[0] = read->red[i];
q[1] = read->green[i];
q[2] = read->blue[i];
q += 3;
}
}
/* Read a palette-ised TIFF image. Again, we only allow 8-bits for now.
/* Read a palette-ised TIFF image. 1/4/8 bits only.
*/
static int
parse_palette( ReadTiff *rtiff, IMAGE *out )
{
PaletteRead *read;
uint16 *tred, *tgreen, *tblue;
PEL *red, *green, *blue;
PEL **maps;
int i;
if( !(read = IM_NEW( out, PaletteRead )) ||
!(read->red = IM_ARRAY( out, 256, PEL )) ||
!(read->green = IM_ARRAY( out, 256, PEL )) ||
!(read->blue = IM_ARRAY( out, 256, PEL )) )
return( -1 );
if( !tfequals( rtiff->tiff, TIFFTAG_SAMPLESPERPIXEL, 1 ) ||
!tfequals( rtiff->tiff, TIFFTAG_BITSPERSAMPLE, 8 ) )
!tfget16( rtiff->tiff, TIFFTAG_BITSPERSAMPLE, &read->bps ) )
return( -1 );
/* Allocate mem for VIPS colour maps.
*/
if( !(red = IM_ARRAY( out, 256, PEL )) ||
!(green = IM_ARRAY( out, 256, PEL )) ||
!(blue = IM_ARRAY( out, 256, PEL )) ||
!(maps = IM_ARRAY( out, 3, PEL * )) )
if( read->bps != 8 && read->bps != 4 &&
read->bps != 2 && read->bps != 1 ) {
im_error( "im_tiff2vips",
_( "%d bits per sample palette image not supported" ),
read->bps );
return( -1 );
}
/* Get maps, convert to 8-bit data.
*/
@ -646,14 +672,11 @@ parse_palette( ReadTiff *rtiff, IMAGE *out )
im_error( "im_tiff2vips", "%s", _( "bad colormap" ) );
return( -1 );
}
for( i = 0; i < 256; i++ ) {
red[i] = tred[i] >> 8;
green[i] = tgreen[i] >> 8;
blue[i] = tblue[i] >> 8;
for( i = 0; i < (1 << read->bps); i++ ) {
read->red[i] = tred[i] >> 8;
read->green[i] = tgreen[i] >> 8;
read->blue[i] = tblue[i] >> 8;
}
maps[0] = red;
maps[1] = green;
maps[2] = blue;
out->Bands = 3;
out->BandFmt = IM_BANDFMT_UCHAR;
@ -661,7 +684,7 @@ parse_palette( ReadTiff *rtiff, IMAGE *out )
out->Type = IM_TYPE_sRGB;
rtiff->sfn = palette_line;
rtiff->client = maps;
rtiff->client = read;
return( 0 );
}
@ -1143,7 +1166,7 @@ tiff_fill_region( REGION *out, void *seq, void *a, void *b )
int x, y, z;
/* Special case: we are filling a single tile exactly sizeed to match
/* Special case: we are filling a single tile exactly sized to match
* the tiff tile, and we have no repacking to do for this format.
*/
if( rtiff->memcpy &&