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      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 exposure from image (handed down as ByteBuffer).
     18 
     19 #include "exposure.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 
     28 jfloat
     29 Java_androidx_media_filterfw_samples_simplecamera_ExposureFilter_overExposureOperator(
     30     JNIEnv* env, jclass clazz, jint width, jint height, jobject imageBuffer) {
     31     if (imageBuffer == 0) {
     32         return 0.0f;
     33     }
     34     const int numPixels = width * height;
     35     unsigned char* srcPtr = static_cast<unsigned char*>(env->GetDirectBufferAddress(imageBuffer));
     36     int output = 0;
     37     float tempLuminance = 0.0f;
     38 
     39     for (int i = 0; i < numPixels; i++) {
     40         tempLuminance = (0.2126f * *(srcPtr + 4 * i) +
     41                         0.7152f * *(srcPtr + 4 * i + 1) +
     42                         0.0722f * *(srcPtr + 4 * i + 2));
     43         if (tempLuminance + 5 >= 255) {
     44             output++;
     45         }
     46     }
     47     return (static_cast<float>(output)) / numPixels;
     48 }
     49 
     50 jfloat
     51 Java_androidx_media_filterfw_samples_simplecamera_ExposureFilter_underExposureOperator(
     52     JNIEnv* env, jclass clazz, jint width, jint height, jobject imageBuffer) {
     53     if (imageBuffer == 0) {
     54         return 0.0f;
     55     }
     56     const int numPixels = width * height;
     57     unsigned char* srcPtr = static_cast<unsigned char*>(env->GetDirectBufferAddress(imageBuffer));
     58     int output = 0;
     59     float tempLuminance = 0.0f;
     60 
     61     for (int i = 0; i < numPixels; i++) {
     62         tempLuminance = (0.2126f * *(srcPtr + 4 * i) +
     63                         0.7152f * *(srcPtr + 4 * i + 1) +
     64                         0.0722f * *(srcPtr + 4 * i + 2));
     65         if (tempLuminance - 5 <= 0) {
     66             output++;
     67         }
     68     }
     69     return (static_cast<float>(output)) / numPixels;
     70 }
     71