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 converts an image to grayscale using the NTSC brightness calculation. 024 */ 025public class GrayscaleFilter extends PointFilter { 026 027 public GrayscaleFilter() { 028 canFilterIndexColorModel = true; 029 } 030 031 public int filterRGB(int x, int y, int rgb) { 032 int a = rgb & 0xff000000; 033 int r = (rgb >> 16) & 0xff; 034 int g = (rgb >> 8) & 0xff; 035 int b = rgb & 0xff; 036// rgb = (r + g + b) / 3; // simple average 037 rgb = (r * 77 + g * 151 + b * 28) >> 8; // NTSC luma 038 return a | (rgb << 16) | (rgb << 8) | rgb; 039 } 040 041 public String toString() { 042 return "Colors/Grayscale"; 043 } 044 045} 046 047