161 lines
3.9 KiB
C
161 lines
3.9 KiB
C
/* @(#) im_Lab2LabQ: quantise FLOAT Lab image into 10 11 11 format
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* 4 bytes per pel: l a b lsbs
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* this is an image wrapper which calls line-wise packing
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* Copyright K.Martinez 3/5/93
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* Modified:
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* 7/6/93 JC
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* - adapted for partial v2
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* 5/5/94 JC
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* - some nint->+0.5, for speed and to ease portability
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* - other nint->rint
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* - now inclues <math.h>!
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* 15/11/94 JC
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* - all nint(), rint() removed for speed
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* - now -128 rather than -127 for a, b
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* - checks input type properly
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* 16/11/94 JC
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* - uses new im_wrap_oneonebuf()
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* 22/5/95 JC
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* - changed L to scale by 10.24, not 10.23
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* 11/7/95 JC
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* - now uses IM_RINT() for rounding
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* 4/9/97 JC
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* - L* = 100.0 now allowed
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* 5/11/00 JC
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* - go int earlier for speed up
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* 20/6/02 JC
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* - oops, were not clipping a/b range correctly
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*/
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/*
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This file is part of VIPS.
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VIPS is free software; you can redistribute it and/or modify
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it under the terms of the GNU Lesser General Public License as published by
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the Free Software Foundation; either version 2 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*/
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/*
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These files are distributed with VIPS - http://www.vips.ecs.soton.ac.uk
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*/
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#ifdef HAVE_CONFIG_H
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#include <config.h>
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#endif /*HAVE_CONFIG_H*/
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#include <vips/intl.h>
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#include <stdio.h>
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#include <math.h>
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#include <vips/vips.h>
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#ifdef WITH_DMALLOC
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#include <dmalloc.h>
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#endif /*WITH_DMALLOC*/
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/* @(#) convert float Lab to packed Lab32 format 10 11 11 bits
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* works only on buffers, not IMAGEs
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* Copyright 1993 K.Martinez
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* Modified: 3/5/93, 16/6/93
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*/
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void
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imb_Lab2LabQ( float *inp, unsigned char *outbuf, int n )
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{
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float *f, fval;
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int lsbs, intv;
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int Xc;
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unsigned char *out;
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out = outbuf;
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f = inp;
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for( Xc = 0; Xc < n; Xc++) {
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/* Scale L up to 10 bits. Add 0.5 rather than call IM_RINT for
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* speed. This will not round negatives correctly! But this
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* does not matter, since L is >0. L*=100.0 -> 1023.
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*/
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intv = 10.23 * f[0] + 0.5; /* scale L up to 10 bits */
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if( intv > 1023 )
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intv = 1023;
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if( intv < 0 )
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intv = 0;
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lsbs = (intv & 0x3) << 6; /* 00000011 -> 11000000 */
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out[0] = (intv >> 2); /* drop bot 2 bits and store */
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fval = 8.0 * f[1]; /* do a */
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intv = IM_RINT( fval );
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if( intv > 1023 )
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intv = 1023;
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else if( intv < -1024 )
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intv = -1024;
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/* Break into bits.
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*/
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lsbs |= (intv & 0x7) << 3; /* 00000111 -> 00111000 */
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out[1] = (intv >> 3); /* drop bot 3 bits & store */
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fval = 8.0 * f[2]; /* do b */
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intv = IM_RINT( fval );
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if( intv > 1023 )
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intv = 1023;
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else if( intv < -1024 )
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intv = -1024;
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lsbs |= (intv & 0x7);
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out[2] = (intv >> 3);
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out[3] = lsbs; /* store lsb band */
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f += 3;
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out += 4;
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}
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}
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int
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im_Lab2LabQ( IMAGE *labim, IMAGE *outim )
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{
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/* Check for uncoded Lab type
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*/
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if( labim->Coding != IM_CODING_NONE ) {
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im_error( "im_Lab2LabQ", "%s",
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_( "uncoded input only" ) );
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return( -1 );
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}
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if( labim->BandFmt != IM_BANDFMT_FLOAT || labim->Bands != 3 ) {
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im_error( "im_Lab2LabQ", "%s",
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_( "three-band float input only" ) );
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return( -1 );
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}
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/* Set up output image.
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*/
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if( im_cp_desc( outim, labim ) )
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return( -1 );
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outim->Bands = 4;
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outim->Type = IM_TYPE_LAB;
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outim->BandFmt = IM_BANDFMT_UCHAR;
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outim->Bbits = 8;
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outim->Coding = IM_CODING_LABQ;
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/* Process.
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*/
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if( im_wrapone( labim, outim,
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(im_wrapone_fn) imb_Lab2LabQ, NULL, NULL ) )
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return( -1 );
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return( 0 );
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}
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