1Android HdrViewfinder Sample 2============================== 3 4This demo shows how to use Camera2 API and RenderScript to implement an HDR viewfinder. 5 6Introduction 7------------ 8 9This demo implements a real-time high-dynamic-range camera viewfinder, by alternating the sensor's 10exposure time between two exposure values on even and odd frames, and then compositing together the 11latest two frames whenever a new frame is captured. 12 13The demo has three modes: Regular auto-exposure viewfinder, split-screen manual exposure, and the 14fused HDR viewfinder. The latter two use manual exposure controlled by the user, by swiping up/down 15on the right and left halves of the viewfinder. The left half controls the exposure time of even 16frames, and the right half controls the exposure time of odd frames. 17 18In split-screen mode, the even frames are shown on the left and the odd frames on the right, so the 19user can see two different exposures of the scene simultaneously. In fused HDR mode, the even/odd 20frames are merged together into a single image. By selecting different exposure values for the 21even/odd frames, the fused image has a higher dynamic range than the regular viewfinder. 22 23The HDR fusion and the split-screen viewfinder processing is done with RenderScript; as is the 24necessary YUV->RGB conversion. The camera subsystem outputs YUV images naturally, while the GPU and 25display subsystems generally only accept RGB data. Therefore, after the images are 26fused/composited, a standard YUV->RGB color transform is applied before the the data is written to 27the output Allocation. The HDR fusion algorithm is very simple, and tends to result in 28lower-contrast scenes, but has very few artifacts and can run very fast. 29 30Data is passed between the subsystems (camera, RenderScript, and display) using the Android {@link 31android.view.Surface} class, which allows for zero-copy transport of large buffers between processes 32and subsystems. 33 34Pre-requisites 35-------------- 36 37- Android SDK v21 38- Android Build Tools v21 39- Android Support Repository 40 41Getting Started 42--------------- 43 44This sample uses the Gradle build system. To build this project, use the 45"gradlew build" command or use "Import Project" in Android Studio. 46 47Screenshots 48----------- 49 50 51 52Support 53------- 54 55- Google+ Community: https://plus.google.com/communities/105153134372062985968 56- Stack Overflow: http://stackoverflow.com/questions/tagged/android 57 58If you've found an error in this sample, please file an issue: 59https://github.com/googlesamples/android-HdrViewfinder 60 61Patches are encouraged, and may be submitted by forking this project and 62submitting a pull request through GitHub. Please see CONTRIBUTING.md for more details. 63 64License 65------- 66 67Copyright 2014 The Android Open Source Project, Inc. 68 69Licensed to the Apache Software Foundation (ASF) under one or more contributor 70license agreements. See the NOTICE file distributed with this work for 71additional information regarding copyright ownership. The ASF licenses this 72file to you under the Apache License, Version 2.0 (the "License"); you may not 73use this file except in compliance with the License. You may obtain a copy of 74the License at 75 76 http://www.apache.org/licenses/LICENSE-2.0 77 78Unless required by applicable law or agreed to in writing, software 79distributed under the License is distributed on an "AS IS" BASIS, WITHOUT 80WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the 81License for the specific language governing permissions and limitations under 82the License. 83
