001/* 002Copyright 2006 Jerry Huxtable 003 004Licensed under the Apache License, Version 2.0 (the "License"); 005you may not use this file except in compliance with the License. 006You may obtain a copy of the License at 007 008 http://www.apache.org/licenses/LICENSE-2.0 009 010Unless required by applicable law or agreed to in writing, software 011distributed under the License is distributed on an "AS IS" BASIS, 012WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 013See the License for the specific language governing permissions and 014limitations under the License. 015*/ 016 017package com.jhlabs.image; 018 019import java.awt.*; 020import java.awt.image.*; 021 022/** 023 * A filter which unpremultiplies an image's alpha. 024 * Note: this does not change the image type of the BufferedImage 025 */ 026public class UnpremultiplyFilter extends PointFilter { 027 028 public UnpremultiplyFilter() { 029 } 030 031 public int filterRGB(int x, int y, int rgb) { 032 int a = (rgb >> 24) & 0xff; 033 int r = (rgb >> 16) & 0xff; 034 int g = (rgb >> 8) & 0xff; 035 int b = rgb & 0xff; 036 if ( a == 0 || a == 255 ) 037 return rgb; 038 039 float f = 255.0f / a; 040 r *= f; 041 g *= f; 042 b *= f; 043 if ( r > 255 ) 044 r = 255; 045 if ( g > 255 ) 046 g = 255; 047 if ( b > 255 ) 048 b = 255; 049 return (a << 24) | (r << 16) | (g << 8) | b; 050 } 051 052 public String toString() { 053 return "Alpha/Unpremultiply"; 054 } 055} 056