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