172 lines
3.6 KiB
C
172 lines
3.6 KiB
C
/* LabS2LabQ()
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*
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* 17/11/93 JC
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* - adapted from im_LabS2LabQ()
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* 16/11/94 JC
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* - adapted to new im_wrap_oneonebuf() function
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* 15/6/95 JC
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* - oops! rounding was broken
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* 6/6/95 JC
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* - added round-to-nearest
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* - somewhat slower ...
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* 21/12/99 JC
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* - a/b ==0 rounding was broken
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* 2/11/09
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* - gtkdoc, cleanup
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* 21/9/12
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* - redo as a class
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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., 51 Franklin Street, Fifth Floor, Boston, MA
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02110-1301 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 <vips/vips.h>
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#include "pcolour.h"
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typedef VipsColourCode VipsLabS2LabQ;
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typedef VipsColourCodeClass VipsLabS2LabQClass;
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G_DEFINE_TYPE( VipsLabS2LabQ, vips_LabS2LabQ, VIPS_TYPE_COLOUR_CODE );
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/* Convert n pels from signed short to IM_CODING_LABQ.
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*/
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static void
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vips_LabS2LabQ_line( VipsColour *colour, VipsPel *out, VipsPel **in, int width )
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{
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signed short *p = (signed short *) in[0];
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unsigned char *q = (unsigned char *) out;
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int i;
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for( i = 0; i < width; i++ ) {
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int l, a, b;
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unsigned char ext;
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/* Get LAB, rounding to 10, 11, 11.
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*/
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l = p[0] + 16;
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l = VIPS_CLIP( 0, l, 32767 );
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l >>= 5;
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/* Make sure we round -ves in the right direction!
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*/
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a = p[1];
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if( a >= 0 )
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a += 16;
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else
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a -= 16;
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a = VIPS_CLIP( -32768, a, 32767 );
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a >>= 5;
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b = p[2];
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if( b >= 0 )
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b += 16;
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else
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b -= 16;
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b = VIPS_CLIP( -32768, b, 32767 );
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b >>= 5;
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p += 3;
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/* Extract top 8 bits.
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*/
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q[0] = l >> 2;
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q[1] = a >> 3;
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q[2] = b >> 3;
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/* Form extension byte.
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*/
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ext = (l << 6) & 0xc0;
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ext |= (a << 3) & 0x38;
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ext |= b & 0x7;
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q[3] = ext;
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q += 4;
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}
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}
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static void
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vips_LabS2LabQ_class_init( VipsLabS2LabQClass *class )
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{
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VipsObjectClass *object_class = (VipsObjectClass *) class;
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VipsColourClass *colour_class = VIPS_COLOUR_CLASS( class );
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object_class->nickname = "LabS2LabQ";
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object_class->description = _( "transform short Lab to LabQ coding" );
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colour_class->process_line = vips_LabS2LabQ_line;
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}
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static void
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vips_LabS2LabQ_init( VipsLabS2LabQ *LabS2LabQ )
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{
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VipsColour *colour = VIPS_COLOUR( LabS2LabQ );
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VipsColourCode *code = VIPS_COLOUR_CODE( LabS2LabQ );
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colour->coding = VIPS_CODING_LABQ;
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colour->interpretation = VIPS_INTERPRETATION_LABQ;
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colour->format = VIPS_FORMAT_UCHAR;
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colour->input_bands = 3;
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colour->bands = 4;
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code->input_coding = VIPS_CODING_NONE;
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code->input_format = VIPS_FORMAT_SHORT;
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}
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/**
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* vips_LabS2LabQ: (method)
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* @in: input image
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* @out: (out): output image
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* @...: %NULL-terminated list of optional named arguments
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*
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* Convert a LabS three-band signed short image to LabQ
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*
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* See also: vips_LabQ2LabS().
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*
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* Returns: 0 on success, -1 on error.
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*/
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int
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vips_LabS2LabQ( VipsImage *in, VipsImage **out, ... )
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{
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va_list ap;
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int result;
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va_start( ap, out );
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result = vips_call_split( "LabS2LabQ", ap, in, out );
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va_end( ap );
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return( result );
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}
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