161 lines
3.9 KiB
C++
161 lines
3.9 KiB
C++
// Copyright 2004 David Hilvert <dhilvert@auricle.dyndns.org>,
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// <dhilvert@ugcs.caltech.edu>
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/* This file is part of the Anti-Lamenessing Engine.
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The Anti-Lamenessing Engine is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3 of the License, or
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(at your option) any later version.
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The Anti-Lamenessing Engine 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 General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with the Anti-Lamenessing Engine; 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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* exposure_default.h: Default exposure properties.
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*/
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#ifndef __exposure_default_h__
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#define __exposure_default_h__
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/*
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* The default exposure is modeled after the simple power transfer function
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* described in
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*
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* http://netpbm.sourceforge.net/doc/pnmgamma.html
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*
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* Note: optimizations in d2/image_rw.h depend on the details of this function.
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*/
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class exposure_default : public exposure {
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public:
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pixel linearize(pixel input) const {
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#if 0
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/*
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* Calling pow() may be expensive on some platforms (e.g.,
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* those lacking hardware support for floating point).
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*/
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return ppow(input, 1/0.45) * get_multiplier();
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#else
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const int table_size = 1024;
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const int table_bits = 10;
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const int interp_bits = 6;
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static int table_is_built = 0;
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static ale_real table[table_size];
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pixel result;
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if (!table_is_built) {
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for (int i = 0; i < table_size; i++) {
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table[i] = pow((float) i / (float) (table_size - 1), 1/0.45);
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}
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table_is_built = 1;
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}
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for (int k = 0; k < 3; k++) {
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/*
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* Clamp.
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*/
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if (input[k] >= 1) {
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result[k] = 1;
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continue;
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} else if (input[k] <= 0) {
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result[k] = 0;
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continue;
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} else if (isnan(input[k])) {
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result[k] = input[k];
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continue;
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}
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int index1 = ale_real_to_int(input[k], 65535);
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int index2 = index1 >> (16 - table_bits);
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int index3 = (index1 >> (16 - table_bits - interp_bits))
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& ((1 << interp_bits) - 1);
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if (index2 >= table_size - 1) {
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result[k] = 1;
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continue;
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}
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ale_real frac = ale_real_from_int((index3 << (16 - interp_bits)), 65535);
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result[k] = (1 - frac) * table[index2] + frac * table[index2 + 1];
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}
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return result * get_multiplier();
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#endif
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}
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pixel unlinearize(pixel input) const {
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#if 0
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/*
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* Calling pow() may be expensive on some platforms (e.g.,
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* those lacking hardware support for floating point).
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*/
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return ppow(input / get_multiplier(), 0.45);
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#else
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input /= get_multiplier();
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const int table_size = 1024;
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const int table_bits = 10;
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const int interp_bits = 6;
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static int table_is_built = 0;
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static ale_real table[table_size];
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pixel result;
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if (!table_is_built) {
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for (int i = 0; i < table_size; i++) {
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table[i] = pow((float) i / (float) (table_size - 1), 0.45);
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}
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table_is_built = 1;
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}
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for (int k = 0; k < 3; k++) {
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/*
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* Clamp.
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*/
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if (input[k] >= 1) {
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result[k] = 1;
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continue;
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} else if (input[k] <= 0) {
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result[k] = 0;
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continue;
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} else if (isnan(input[k])) {
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result[k] = input[k];
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continue;
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}
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int index1 = ale_real_to_int(input[k], 65535);
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int index2 = index1 >> (16 - table_bits);
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int index3 = (index1 >> (16 - table_bits - interp_bits))
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& ((1 << interp_bits) - 1);
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if (index2 >= table_size - 1) {
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result[k] = 1;
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continue;
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}
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ale_real frac = ale_real_from_int((index3 << (16 - interp_bits)), 65535);
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result[k] = (1 - frac) * table[index2] + frac * table[index2 + 1];
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}
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return result;
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#endif
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}
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};
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#endif
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