gimp/app/paint-funcs/scale-region.h

52 lines
2.0 KiB
C

/* GIMP - The GNU Image Manipulation Program
* Copyright (C) 1995 Spencer Kimball and Peter Mattis
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 3 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 General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#ifndef __SCALE_REGION_H__
#define __SCALE_REGION_H__
#define LANCZOS_SPP (4000) /* number of data pts per unit x in lookup table */
#define LANCZOS_MIN (1.0/LANCZOS_SPP)
#define LANCZOS_WIDTH (3) /* 3 for Lanczos3 code, for L4 prefer DUAL_LANCZOS below */
#define LANCZOS_WIDTH2 (1 + (LANCZOS_WIDTH * 2))
#define LANCZOS_SAMPLES (LANCZOS_SPP * (LANCZOS_WIDTH + 1))
void scale_region (PixelRegion *srcPR,
PixelRegion *destPR,
GimpInterpolationType interpolation,
GimpProgressFunc progress_callback,
gpointer progress_data);
gfloat * create_lanczos_lookup (void);
#endif /* __SCALE_REGION_H__ */
/*
* Determining LANCZOS_SPP value
*
* 1000 points per unit will produce typically 1 bit of error per channel
* on a Lanczos3 window. 4000 should not produce a detectable error caused
* by lookup table size.
* On 8b colours ie 24bit RGB this req 80kB of memory comparable to a small
* 250x150 px image. Filling the array is a small part of the time required
* for the transform.
* This will need reviewing when GIMP handles images with more bytes per pixel.
*/