1 2Android HdrViewfinder Sample 3=================================== 4 5This demo implements a real-time high-dynamic-range camera viewfinder, by alternating 6the sensor's exposure time between two exposure values on even and odd frames, and then 7compositing together the latest two frames whenever a new frame is captured. 8 9Introduction 10------------ 11 12A small demo of advanced camera functionality with the Android camera2 API. 13 14This demo implements a real-time high-dynamic-range camera viewfinder, 15by alternating the sensor's exposure time between two exposure values on even and odd 16frames, and then compositing together the latest two frames whenever a new frame is 17captured. 18 19The demo has three modes: Regular auto-exposure viewfinder, split-screen manual exposure, 20and the fused HDR viewfinder. The latter two use manual exposure controlled by the user, 21by swiping up/down on the right and left halves of the viewfinder. The left half controls 22the exposure time of even frames, and the right half controls the exposure time of odd frames. 23 24In split-screen mode, the even frames are shown on the left and the odd frames on the right, 25so the user can see two different exposures of the scene simultaneously. In fused HDR mode, 26the even/odd frames are merged together into a single image. By selecting different exposure 27values for the even/odd frames, the fused image has a higher dynamic range than the regular 28viewfinder. 29 30The HDR fusion and the split-screen viewfinder processing is done with RenderScript; as is the 31necessary YUV->RGB conversion. The camera subsystem outputs YUV images naturally, while the GPU 32and display subsystems generally only accept RGB data. Therefore, after the images are 33fused/composited, a standard YUV->RGB color transform is applied before the the data is written 34to the output Allocation. The HDR fusion algorithm is very simple, and tends to result in 35lower-contrast scenes, but has very few artifacts and can run very fast. 36 37Data is passed between the subsystems (camera, RenderScript, and display) using the 38Android [android.view.Surface][1] class, which allows for zero-copy transport of large 39buffers between processes and subsystems. 40 41[1]: http://developer.android.com/reference/android/view/Surface.html 42 43Pre-requisites 44-------------- 45 46- Android SDK 27 47- Android Build Tools v27.0.2 48- Android Support Repository 49 50Screenshots 51------------- 52 53<img src="screenshots/image1.png" height="400" alt="Screenshot"/> 54 55Getting Started 56--------------- 57 58This sample uses the Gradle build system. To build this project, use the 59"gradlew build" command or use "Import Project" in Android Studio. 60 61Support 62------- 63 64- Google+ Community: https://plus.google.com/communities/105153134372062985968 65- Stack Overflow: http://stackoverflow.com/questions/tagged/android 66 67If you've found an error in this sample, please file an issue: 68https://github.com/googlesamples/android-HdrViewfinder 69 70Patches are encouraged, and may be submitted by forking this project and 71submitting a pull request through GitHub. Please see CONTRIBUTING.md for more details. 72 73License 74------- 75 76Copyright 2017 The Android Open Source Project, Inc. 77 78Licensed to the Apache Software Foundation (ASF) under one or more contributor 79license agreements. See the NOTICE file distributed with this work for 80additional information regarding copyright ownership. The ASF licenses this 81file to you under the Apache License, Version 2.0 (the "License"); you may not 82use this file except in compliance with the License. You may obtain a copy of 83the License at 84 85http://www.apache.org/licenses/LICENSE-2.0 86 87Unless required by applicable law or agreed to in writing, software 88distributed under the License is distributed on an "AS IS" BASIS, WITHOUT 89WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the 90License for the specific language governing permissions and limitations under 91the License. 92
