GPUImageGrayscaleFilter.java

/*
 * Copyright (C) 2012 CyberAgent
 *
 * Licensed 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 jp.co.cyberagent.android.gpuimage;

/**
 * Applies a grayscale effect to the image.
 */
public class GPUImageGrayscaleFilter extends GPUImageFilter {
    public static final String GRAYSCALE_FRAGMENT_SHADER = "" +
            "precision highp float;\n" +
            "\n" +
            "varying vec2 textureCoordinate;\n" +
            "\n" +
            "uniform sampler2D inputImageTexture;\n" +
            "\n" +
            "const highp vec3 W = vec3(0.2125, 0.7154, 0.0721);\n" +
            "\n" +
            "void main()\n" +
            "{\n" +
            "  lowp vec4 textureColor = texture2D(inputImageTexture, textureCoordinate);\n" +
            "  float luminance = dot(textureColor.rgb, W);\n" +
            "\n" +
            "  gl_FragColor = vec4(vec3(luminance), textureColor.a);\n" +
            "}";

    public GPUImageGrayscaleFilter() {
        super(NO_FILTER_VERTEX_SHADER, GRAYSCALE_FRAGMENT_SHADER);
    }
}