1 /*
2 * Copyright (C) 2012 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 // Stats (mean and stdev) scoring in the native.
18
19 #include "stats_scorer.h"
20
21 #include <jni.h>
22 #include <math.h>
23
Java_androidx_media_filterpacks_numeric_StatsFilter_score(JNIEnv * env,jobject thiz,jobject imageBuffer,jfloatArray statsArray)24 void Java_androidx_media_filterpacks_numeric_StatsFilter_score(
25 JNIEnv* env, jobject thiz, jobject imageBuffer, jfloatArray statsArray)
26 {
27 unsigned char* pImg = static_cast<unsigned char*>(env->GetDirectBufferAddress(imageBuffer));
28 int numPixels = env->GetDirectBufferCapacity(imageBuffer); // 1 byte per pixel
29 float sum = 0.0;
30 float sumSquares = 0.0;
31
32 for (int i = 0; i < numPixels; ++i) {
33 float val = static_cast<float>(pImg[i]);
34 sum += val;
35 sumSquares += val * val;
36 }
37 jfloat result[2];
38 result[0] = sum / numPixels; // mean
39 result[1] = sqrt((sumSquares - numPixels * result[0] * result[0]) / (numPixels - 1)); // stdev.
40 env->SetFloatArrayRegion(statsArray, 0, 2, result);
41 }
42
Java_androidx_media_filterpacks_numeric_StatsFilter_regionscore(JNIEnv * env,jobject thiz,jobject imageBuffer,jint width,jint height,jfloat left,jfloat top,jfloat right,jfloat bottom,jfloatArray statsArray)43 void Java_androidx_media_filterpacks_numeric_StatsFilter_regionscore(
44 JNIEnv* env, jobject thiz, jobject imageBuffer, jint width, jint height,
45 jfloat left, jfloat top, jfloat right, jfloat bottom, jfloatArray statsArray)
46 {
47 unsigned char* pImg = static_cast<unsigned char*>(env->GetDirectBufferAddress(imageBuffer));
48 int xStart = static_cast<int>(width * left);
49 int xEnd = static_cast<int>(width * right);
50 int yStart = static_cast<int>(height * top);
51 int yEnd = static_cast<int>(height * bottom);
52 int numPixels = (xEnd - xStart) * (yEnd - yStart);
53 float sum = 0.0;
54 float sumSquares = 0.0;
55
56 for (int y = yStart; y < yEnd; y++) {
57 int disp = width * y;
58 for (int x = xStart; x < xEnd; ++x) {
59 float val = static_cast<float>(*(pImg + disp + x));
60 sum += val;
61 sumSquares += val * val;
62 }
63 }
64 jfloat result[2];
65 result[0] = sum / numPixels; // mean
66 result[1] = (numPixels == 1) ?
67 0 : sqrt((sumSquares - numPixels * result[0] * result[0]) / (numPixels - 1)); // stdev.
68 env->SetFloatArrayRegion(statsArray, 0, 2, result);
69 }
70
71