| /* Gamma-correct image with factor gammafactor. |
| * |
| * Copyright: 1990, N. Dessipris. |
| * |
| * Written on: 19/07/1990 |
| * Modified on: |
| * 19/6/95 JC |
| * - redone as library function |
| * 23/3/10 |
| * - gtkdoc |
| * - 16 bit as well |
| */ |
| |
| /* |
| |
| This file is part of VIPS. |
| |
| VIPS is free software; you can redistribute it and/or modify |
| it under the terms of the GNU Lesser General Public License as published by |
| the Free Software Foundation; either version 2 of the License, or |
| (at your option) any later version. |
| |
| This program is distributed in the hope that it will be useful, |
| but WITHOUT ANY WARRANTY; without even the implied warranty of |
| MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| GNU Lesser General Public License for more details. |
| |
| You should have received a copy of the GNU Lesser General Public License |
| along with this program; if not, write to the Free Software |
| Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA |
| |
| */ |
| |
| /* |
| |
| These files are distributed with VIPS - http://www.vips.ecs.soton.ac.uk |
| |
| */ |
| |
| #ifdef HAVE_CONFIG_H |
| #include <config.h> |
| #endif /*HAVE_CONFIG_H*/ |
| #include <vips/intl.h> |
| |
| #include <stdio.h> |
| |
| #include <vips/vips.h> |
| |
| #ifdef WITH_DMALLOC |
| #include <dmalloc.h> |
| #endif /*WITH_DMALLOC*/ |
| |
| /** |
| * im_gammacorrect: |
| * @in: input image |
| * @out: output image |
| * @exponent: gamma factor |
| * |
| * Gamma-correct an 8- or 16-bit unsigned image with a lookup table. The |
| * output format is the same as the input format. |
| * |
| * See also: im_identity(), im_powtra(), im_maplut() |
| * |
| * Returns: 0 on success, -1 on error |
| */ |
| int |
| im_gammacorrect( IMAGE *in, IMAGE *out, double exponent ) |
| { |
| IMAGE *t[4]; |
| double mx1, mx2; |
| |
| if( im_open_local_array( out, t, 4, "im_gammacorrect", "p" ) || |
| im_check_u8or16( "im_gammacorrect", in ) || |
| im_piocheck( in, out ) || |
| (in->BandFmt == IM_BANDFMT_UCHAR ? |
| im_identity( t[0], 1 ) : |
| im_identity_ushort( t[0], 1, 65536 )) || |
| im_powtra( t[0], t[1], exponent ) || |
| im_max( t[0], &mx1 ) || |
| im_max( t[1], &mx2 ) || |
| im_lintra( mx1 / mx2, t[1], 0, t[2] ) || |
| im_clip2fmt( t[2], t[3], in->BandFmt ) || |
| im_maplut( in, out, t[3] ) ) |
| return( -1 ); |
| |
| return( 0 ); |
| } |
