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- /* Copyright (C) 1995, 2000 Aladdin Enterprises. All rights reserved.
-
- This software is provided AS-IS with no warranty, either express or
- implied.
-
- This software is distributed under license and may not be copied,
- modified or distributed except as expressly authorized under the terms
- of the license contained in the file LICENSE in this distribution.
-
- For more information about licensing, please refer to
- http://www.ghostscript.com/licensing/. For information on
- commercial licensing, go to http://www.artifex.com/licensing/ or
- contact Artifex Software, Inc., 101 Lucas Valley Road #110,
- San Rafael, CA 94903, U.S.A., +1(415)492-9861.
- */
- /* $Id: gxctable.c,v 1.5 2002/02/21 22:24:53 giles Exp $ */
- /* Color table lookup and interpolation */
- #include "gx.h"
- #include "gxfixed.h"
- #include "gxfrac.h"
- #include "gxctable.h"
- /* See gxctable.h for the API and structure definitions. */
- /*
- * Define an implementation that simply picks the nearest value without
- * any interpolation.
- */
- void
- gx_color_interpolate_nearest(const fixed * pi,
- const gx_color_lookup_table * pclt, frac * pv)
- {
- const int *pdim = pclt->dims;
- int m = pclt->m;
- const gs_const_string *table = pclt->table;
- if (pclt->n > 3) {
- table += fixed2int_var_rounded(pi[0]) * pdim[1];
- ++pi, ++pdim;
- } {
- int ic = fixed2int_var_rounded(pi[2]);
- int ib = fixed2int_var_rounded(pi[1]);
- int ia = fixed2int_var_rounded(pi[0]);
- const byte *p = pclt->table[ia].data + (ib * pdim[2] + ic) * m;
- int j;
- for (j = 0; j < m; ++j, ++p)
- pv[j] = byte2frac(*p);
- }
- }
- /*
- * Define an implementation that uses trilinear interpolation.
- */
- private void
- interpolate_accum(const fixed * pi, const gx_color_lookup_table * pclt,
- frac * pv, fixed factor)
- {
- const int *pdim = pclt->dims;
- int m = pclt->m;
- if (pclt->n > 3) {
- /* Do two 3-D interpolations, interpolating between them. */
- gx_color_lookup_table clt3;
- int ix = fixed2int_var(pi[0]);
- fixed fx = fixed_fraction(pi[0]);
- clt3.n = 3;
- clt3.dims[0] = pdim[1]; /* needed only for range checking */
- clt3.dims[1] = pdim[2];
- clt3.dims[2] = pdim[3];
- clt3.m = m;
- clt3.table = pclt->table + ix * pdim[1];
- interpolate_accum(pi + 1, &clt3, pv, fixed_1);
- if (ix == pdim[0] - 1)
- return;
- clt3.table += pdim[1];
- interpolate_accum(pi + 1, &clt3, pv, fx);
- } else {
- int ic = fixed2int_var(pi[2]);
- fixed fc = fixed_fraction(pi[2]);
- uint dc1 = (ic == pdim[2] - 1 ? 0 : m);
- int ib = fixed2int_var(pi[1]);
- fixed fb = fixed_fraction(pi[1]);
- uint db1 = (ib == pdim[1] - 1 ? 0 : pdim[2] * m);
- uint dbc = (ib * pdim[2] + ic) * m;
- uint dbc1 = db1 + dc1;
- int ia = fixed2int_var(pi[0]);
- fixed fa = fixed_fraction(pi[0]);
- const byte *pa0 = pclt->table[ia].data + dbc;
- const byte *pa1 =
- (ia == pdim[0] - 1 ? pa0 : pclt->table[ia + 1].data + dbc);
- int j;
- /* The values to be interpolated are */
- /* pa{0,1}[{0,db1,dc1,dbc1}]. */
- for (j = 0; j < m; ++j, ++pa0, ++pa1) {
- frac v000 = byte2frac(pa0[0]);
- frac v001 = byte2frac(pa0[dc1]);
- frac v010 = byte2frac(pa0[db1]);
- frac v011 = byte2frac(pa0[dbc1]);
- frac v100 = byte2frac(pa1[0]);
- frac v101 = byte2frac(pa1[dc1]);
- frac v110 = byte2frac(pa1[db1]);
- frac v111 = byte2frac(pa1[dbc1]);
- frac rv;
- frac v00 = v000 +
- (frac) arith_rshift((long)fc * (v001 - v000),
- _fixed_shift);
- frac v01 = v010 +
- (frac) arith_rshift((long)fc * (v011 - v010),
- _fixed_shift);
- frac v10 = v100 +
- (frac) arith_rshift((long)fc * (v101 - v100),
- _fixed_shift);
- frac v11 = v110 +
- (frac) arith_rshift((long)fc * (v111 - v110),
- _fixed_shift);
- frac v0 = v00 +
- (frac) arith_rshift((long)fb * (v01 - v00),
- _fixed_shift);
- frac v1 = v10 +
- (frac) arith_rshift((long)fb * (v11 - v10),
- _fixed_shift);
- rv = v0 +
- (frac) arith_rshift((long)fa * (v1 - v0),
- _fixed_shift);
- if (factor == fixed_1)
- pv[j] = rv;
- else
- pv[j] += (frac) arith_rshift((long)factor * (rv - pv[j]),
- _fixed_shift);
- }
- }
- }
- void
- gx_color_interpolate_linear(const fixed * pi,
- const gx_color_lookup_table * pclt, frac * pv)
- {
- interpolate_accum(pi, pclt, pv, fixed_1);
- }
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