| /* im_scale |
| * |
| * Author: John Cupitt |
| * Written on: 22/4/93 |
| * Modified on: |
| * 30/6/93 JC |
| * - adapted for partial v2 |
| * - ANSI |
| * 31/8/93 JC |
| * - calculation of offset now includes scale |
| * 8/5/06 |
| * - set Type on output too |
| * 16/10/06 |
| * - what? no, don't set Type, useful to be able to scale histograms, for |
| * example |
| * 1/2/10 |
| * - gtkdoc |
| */ |
| |
| /* |
| |
| 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 <stdlib.h> |
| |
| #include <vips/vips.h> |
| |
| #ifdef WITH_DMALLOC |
| #include <dmalloc.h> |
| #endif /*WITH_DMALLOC*/ |
| |
| /** |
| * im_scale: |
| * @in: input image |
| * @out: output image |
| * |
| * Search the image for the maximum and minimum value, then return the image |
| * as unsigned 8-bit, scaled so that the maximum value is 255 and the |
| * minimum is zero. |
| * |
| * See also: im_clip2fmt(), im_scaleps(). |
| * |
| * Returns: 0 on success, -1 on error |
| */ |
| int |
| im_scale( IMAGE *in, IMAGE *out ) |
| { |
| DOUBLEMASK *stats; |
| IMAGE *t = im_open_local( out, "im_scale:1", "p" ); |
| double mx, mn; |
| double scale, offset; |
| |
| /* Measure min and max, calculate transform. |
| */ |
| if( !t || !(stats = im_stats( in )) ) |
| return( -1 ); |
| mn = stats->coeff[0]; |
| mx = stats->coeff[1]; |
| im_free_dmask( stats ); |
| |
| if( mn == mx ) |
| /* Range of zero: just return black. |
| */ |
| return( im_black( out, in->Xsize, in->Ysize, in->Bands ) ); |
| scale = 255.0 / (mx - mn); |
| offset = -(mn * scale); |
| |
| /* Transform! |
| */ |
| if( im_lintra( scale, in, offset, t ) || |
| im_clip2fmt( t, out, IM_BANDFMT_UCHAR ) ) |
| return( -1 ); |
| |
| return( 0 ); |
| } |
