01: /**
02: * Copyright (c) 2005, www.pdfbox.org
03: * All rights reserved.
04: *
05: * Redistribution and use in source and binary forms, with or without
06: * modification, are permitted provided that the following conditions are met:
07: *
08: * 1. Redistributions of source code must retain the above copyright notice,
09: * this list of conditions and the following disclaimer.
10: * 2. Redistributions in binary form must reproduce the above copyright notice,
11: * this list of conditions and the following disclaimer in the documentation
12: * and/or other materials provided with the distribution.
13: * 3. Neither the name of pdfbox; nor the names of its
14: * contributors may be used to endorse or promote products derived from this
15: * software without specific prior written permission.
16: *
17: * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
18: * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19: * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
20: * DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE FOR ANY
21: * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
22: * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
23: * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
24: * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
25: * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
26: * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
27: *
28: * http://www.pdfbox.org
29: *
30: */package org.pdfbox.pdmodel.graphics.predictor;
31:
32: /**
33: * We can use raw on the right hand side of
34: * the decoding formula because it is already decoded.
35: *
36: * <code>average(i,j) = raw(i,j) + (raw(i-1,j)+raw(i,j-1)/2</code>
37: *
38: * decoding
39: *
40: * <code>raw(i,j) = avarage(i,j) - (raw(i-1,j)+raw(i,j-1)/2</code>
41: *
42: * @author xylifyx@yahoo.co.uk
43: * @version $Revision: 1.3 $
44: */
45: public class Average extends PredictorAlgorithm {
46: /**
47: * Not an optimal version, but close to the def.
48: *
49: * {@inheritDoc}
50: */
51: public void encodeLine(byte[] src, byte[] dest, int srcDy,
52: int srcOffset, int destDy, int destOffset) {
53: int bpl = getWidth() * getBpp();
54: for (int x = 0; x < bpl; x++) {
55: dest[x + destOffset] = (byte) (src[x + srcOffset] - ((leftPixel(
56: src, srcOffset, srcDy, x) + abovePixel(src,
57: srcOffset, srcDy, x)) >>> 2));
58: }
59: }
60:
61: /**
62: * {@inheritDoc}
63: */
64: public void decodeLine(byte[] src, byte[] dest, int srcDy,
65: int srcOffset, int destDy, int destOffset) {
66: int bpl = getWidth() * getBpp();
67: for (int x = 0; x < bpl; x++) {
68: dest[x + destOffset] = (byte) (src[x + srcOffset] + ((leftPixel(
69: dest, destOffset, destDy, x) + abovePixel(dest,
70: destOffset, destDy, x)) >>> 2));
71: }
72: }
73: }
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