| /* |
| * Licensed to the Apache Software Foundation (ASF) under one or more |
| * contributor license agreements. See the NOTICE file distributed with |
| * this work for additional information regarding copyright ownership. |
| * The ASF licenses this file to You under the Apache License, Version 2.0 |
| * (the "License"); you may not use this file except in compliance with |
| * the License. You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| package org.apache.commons.sanselan.formats.png.scanlinefilters; |
| |
| import java.io.IOException; |
| |
| import org.apache.commons.sanselan.ImageReadException; |
| |
| public class ScanlineFilterSub extends ScanlineFilter |
| { |
| private final int BytesPerPixel; |
| |
| public ScanlineFilterSub(int BytesPerPixel) |
| { |
| this.BytesPerPixel = BytesPerPixel; |
| } |
| |
| public void unfilter(byte src[], byte dst[], byte up[]) |
| throws ImageReadException, IOException |
| { |
| for (int i = 0; i < src.length; i++) |
| { |
| int prev_index = i - BytesPerPixel; |
| if (prev_index >= 0) |
| dst[i] = (byte) ((src[i] + dst[prev_index]) % 256); |
| // dst[i] = 0xff & (src[i] + src[prev_index]); |
| else |
| dst[i] = src[i]; |
| |
| // if(i<10) |
| // System.out.println("\t" + i + ": " + dst[i] + " (" + src[i] + ", " + prev_index + ")"); |
| |
| // dst[i] = src[i]; |
| } |
| } |
| } |