92 lines
3.8 KiB
Markdown
92 lines
3.8 KiB
Markdown
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Android HdrViewfinder Sample
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===================================
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This demo implements a real-time high-dynamic-range camera viewfinder, by alternating
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the sensor's exposure time between two exposure values on even and odd frames, and then
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compositing together the latest two frames whenever a new frame is captured.
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Introduction
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------------
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A small demo of advanced camera functionality with the Android camera2 API.
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This demo implements a real-time high-dynamic-range camera viewfinder,
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by alternating the sensor's exposure time between two exposure values on even and odd
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frames, and then compositing together the latest two frames whenever a new frame is
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captured.
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The demo has three modes: Regular auto-exposure viewfinder, split-screen manual exposure,
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and the fused HDR viewfinder. The latter two use manual exposure controlled by the user,
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by swiping up/down on the right and left halves of the viewfinder. The left half controls
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the exposure time of even frames, and the right half controls the exposure time of odd frames.
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In split-screen mode, the even frames are shown on the left and the odd frames on the right,
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so the user can see two different exposures of the scene simultaneously. In fused HDR mode,
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the even/odd frames are merged together into a single image. By selecting different exposure
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values for the even/odd frames, the fused image has a higher dynamic range than the regular
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viewfinder.
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The HDR fusion and the split-screen viewfinder processing is done with RenderScript; as is the
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necessary YUV->RGB conversion. The camera subsystem outputs YUV images naturally, while the GPU
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and display subsystems generally only accept RGB data. Therefore, after the images are
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fused/composited, a standard YUV->RGB color transform is applied before the the data is written
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to the output Allocation. The HDR fusion algorithm is very simple, and tends to result in
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lower-contrast scenes, but has very few artifacts and can run very fast.
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Data is passed between the subsystems (camera, RenderScript, and display) using the
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Android [android.view.Surface][1] class, which allows for zero-copy transport of large
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buffers between processes and subsystems.
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[1]: http://developer.android.com/reference/android/view/Surface.html
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Pre-requisites
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--------------
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- Android SDK 27
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- Android Build Tools v27.0.2
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- Android Support Repository
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Screenshots
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-------------
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<img src="screenshots/image1.png" height="400" alt="Screenshot"/>
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Getting Started
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---------------
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This sample uses the Gradle build system. To build this project, use the
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"gradlew build" command or use "Import Project" in Android Studio.
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Support
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-------
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- Google+ Community: https://plus.google.com/communities/105153134372062985968
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- Stack Overflow: http://stackoverflow.com/questions/tagged/android
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If you've found an error in this sample, please file an issue:
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https://github.com/googlesamples/android-HdrViewfinder
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Patches are encouraged, and may be submitted by forking this project and
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submitting a pull request through GitHub. Please see CONTRIBUTING.md for more details.
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License
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-------
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Copyright 2017 The Android Open Source Project, Inc.
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Licensed to the Apache Software Foundation (ASF) under one or more contributor
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license agreements. See the NOTICE file distributed with this work for
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additional information regarding copyright ownership. The ASF licenses this
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file to you under the Apache License, Version 2.0 (the "License"); you may not
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use this file except in compliance with the License. You may obtain a copy of
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the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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License for the specific language governing permissions and limitations under
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the License.
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