1 /* 2 * Copyright (C) 2013 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 // Native function to extract brightness from image (handed down as ByteBuffer). 18 19 #include "brightness.h" 20 21 #include <math.h> 22 #include <string.h> 23 #include <jni.h> 24 #include <unistd.h> 25 #include <android/log.h> 26 27 jfloat 28 Java_androidx_media_filterfw_samples_simplecamera_AvgBrightnessFilter_brightnessOperator( 29 JNIEnv* env, jclass clazz, jint width, jint height, jobject imageBuffer) { 30 31 if (imageBuffer == 0) { 32 return 0.0f; 33 } 34 float pixelTotals[] = { 0.0f, 0.0f, 0.0f }; 35 const int numPixels = width * height; 36 unsigned char* srcPtr = static_cast<unsigned char*>(env->GetDirectBufferAddress(imageBuffer)); 37 for (int i = 0; i < numPixels; i++) { 38 pixelTotals[0] += *(srcPtr + 4 * i); 39 pixelTotals[1] += *(srcPtr + 4 * i + 1); 40 pixelTotals[2] += *(srcPtr + 4 * i + 2); 41 } 42 float avgPixels[] = { 0.0f, 0.0f, 0.0f }; 43 44 avgPixels[0] = pixelTotals[0] / numPixels; 45 avgPixels[1] = pixelTotals[1] / numPixels; 46 avgPixels[2] = pixelTotals[2] / numPixels; 47 float returnValue = sqrt(0.241f * avgPixels[0] * avgPixels[0] + 48 0.691f * avgPixels[1] * avgPixels[1] + 49 0.068f * avgPixels[2] * avgPixels[2]); 50 51 return returnValue / 255; 52 } 53
