I am creating an app for taking pictures and sending them via http POST to my server. Since I only need grayscale data on the server side, it would by much better to just take the grayscale picture and not having to convert it.
I am using Camera2 API and I have an issue with setting properties for CaptureRequest.Builder instance. With this:
final CaptureRequest.Builder captureBuilder = cameraDevice.createCaptureRequest(CameraDevice.TEMPLATE_STILL_CAPTURE);
captureBuilder.set(CaptureRequest.CONTROL_EFFECT_MODE, CaptureRequest.CONTROL_EFFECT_MODE_NEGATIVE);
It takes a negative photo.
But this:
final CaptureRequest.Builder captureBuilder = cameraDevice.createCaptureRequest(CameraDevice.TEMPLATE_STILL_CAPTURE);
captureBuilder.set(CaptureRequest.CONTROL_EFFECT_MODE, CaptureRequest.CONTROL_EFFECT_MODE_MONO);
Does absolutely nothing. No grayscale. just a normal picture.
You need to look at the list of supported effects on your device, to see if MONO is actually supported by it.
If you only care about luminance, you could just capture YUV_420_888 buffers instead of JPEG, and only send the Y buffer to the server. That won't get you automatic JPEG encoding, though.
Also note that generally under the hood, JPEG images are encoded in YUV; so if you dig into your JPEG decoder library, you may be able to get the image data before conversion to RGB, and simply ignore the chroma channels.
captureRequestBuilder.set(CaptureRequest.CONTROL_EFFECT_MODE,CameraMetadata.CONTROL_EFFECT_MODE_MONO);
you can use this`
Related
I am working on Camera2 api with real time Image processing, i get
found method
onCaptureProgressed(CameraCaptureSession, CaptureRequest, CaptureResult)
call on every capturing fram but i have no idea how to get byte[] or data from CaptureResult
You can't get image data from CaptureResult; it only provides image metadata.
Take a look at the Camera2Basic sample app, which captures JPEG images with an ImageReader. If you change the JPEG format to YUV, set the resolution to preview size, and set the ImageReader Surface as a target for the preview repeating request, you'll get an ImageReader.Image for every frame captured.
I'm trying to create an app that processes camera images in real time and displays them on screen. I'm using the camera2 API. I have created a native library to process the images using OpenCV.
So far I have managed to set up an ImageReader that receives images in YUV_420_888 format like this.
mImageReader = ImageReader.newInstance(
mPreviewSize.getWidth(),
mPreviewSize.getHeight(),
ImageFormat.YUV_420_888,
4);
mImageReader.setOnImageAvailableListener(mOnImageAvailableListener, mImageReaderHandler);
From there I'm able to get the image planes (Y, U and V), get their ByteBuffer objects and pass them to my native function. This happens in the mOnImageAvailableListener:
Image image = reader.acquireLatestImage();
Image.Plane[] planes = image.getPlanes();
Image.Plane YPlane = planes[0];
Image.Plane UPlane = planes[1];
Image.Plane VPlane = planes[2];
ByteBuffer YPlaneBuffer = YPlane.getBuffer();
ByteBuffer UPlaneBuffer = UPlane.getBuffer();
ByteBuffer VPlaneBuffer = VPlane.getBuffer();
myNativeMethod(YPlaneBuffer, UPlaneBuffer, VPlaneBuffer, w, h);
image.close();
On the native side I'm able to get the data pointers from the buffers, create a cv::Mat from the data and perform the image processing.
Now the next step would be to show my processed output, but I'm unsure how to show my processed image. Any help would be greatly appreciated.
Generally speaking, you need to send the processed image data to an Android view.
The most performant option is to get an android.view.Surface object to draw into - you can get one from a SurfaceView (via SurfaceHolder) or a TextureView (via SurfaceTexture). Then you can pass that Surface through JNI to your native code, and there use the NDK methods:
ANativeWindow_fromSurface to get an ANativeWindow
The various ANativeWindow methods to set the output buffer size and format, and then draw your processed data into it.
Use setBuffersGeometry() to configure the output size, then lock() to get an ANativeWindow_Buffer. Write your image data to ANativeWindow_Buffer.bits, and then send the buffer off with unlockAndPost().
Generally, you should probably stick to RGBA_8888 as the most compatible format; technically only it and two other RGB variants are officially supported. So if your processed image is in YUV, you'd need to convert it to RGBA first.
You'll also need to ensure that the aspect ratio of your output view matches that of the dimensions you set; by default, Android's Views will just scale those internal buffers to the size of the output View, possibly stretching it in the process.
You can also set the format to one of Android's internal YUV formats, but this is not guaranteed to work!
I've tried the ANativeWindow approach, but it's a pain to set up and I haven't managed to do it correctly. In the end I just gave up and imported OpenCV4Android library which simplifies things by converting camera data to a RGBA Mat behind the scenes.
I would like to perform face detection / tracking on a video file (e.g. an MP4 from the users gallery) using the Android Vision FaceDetector API. I can see many examples on using the CameraSource class to perform face tracking on the stream coming directly from the camera (e.g. on the android-vision github), but nothing on video files.
I tried looking at the source code for CameraSource through Android Studio, but it is obfuscated, and I couldn't see the original online. I image there are many commonalities between using the camera and using a file. Presumably I just play the video file on a Surface, and then pass that to a pipeline.
Alternatively I can see that Frame.Builder has functions setImageData and setTimestampMillis. If I was able to read in the video as ByteBuffer, how would I pass that to the FaceDetector API? I guess this question is similar, but no answers. Similarly, decode the video into Bitmap frames and pass that to setBitmap.
Ideally I don't want to render the video to the screen, and the processing should happen as fast as the FaceDetector API is capable of.
Alternatively I can see that Frame.Builder has functions setImageData and setTimestampMillis. If I was able to read in the video as ByteBuffer, how would I pass that to the FaceDetector API?
Simply call SparseArray<Face> faces = detector.detect(frame); where detector has to be created like this:
FaceDetector detector = new FaceDetector.Builder(context)
.setProminentFaceOnly(true)
.build();
If processing time is not an issue, using MediaMetadataRetriever.getFrameAtTime solves the question. As Anton suggested, you can also use FaceDetector.detect:
Bitmap bitmap;
Frame frame;
SparseArray<Face> faces;
MediaMetadataRetriever mMMR = new MediaMetadataRetriever();
mMMR.setDataSource(videoPath);
String timeMs = mMMR.extractMetadata(MediaMetadataRetriever.METADATA_KEY_DURATION); // video time in ms
int totalVideoTime= 1000*Integer.valueOf(timeMs); // total video time, in uS
for (int time_us=1;time_us<totalVideoTime;time_us+=deltaT){
bitmap = mMMR.getFrameAtTime(time_us, MediaMetadataRetriever.OPTION_CLOSEST_SYNC); // extract a bitmap element from the closest key frame from the specified time_us
if (bitmap==null) break;
frame = new Frame.Builder().setBitmap(bitmap).build(); // generates a "Frame" object, which can be fed to a face detector
faces = detector.detect(frame); // detect the faces (detector is a FaceDetector)
// TODO ... do something with "faces"
}
where deltaT=1000000/fps, and fps is the desired number of frames per second. For example, if you want to extract 4 frames every second, deltaT=250000
(Note that faces will be overwritten on every iteration, so you should do something (store/report results) inside the loop
I'm using the camera2 api to capture a burst of images. To ensure fastest capture speed, I am currently using yuv420888.
(jpeg results in approximately 3 fps capture while yuv results in approximately 30fps)
So what I'm asking is how can I access the yuv values for each pixel in the image.
i.e.
Image image = reader.AcquireNextImage();
Pixel pixel = image.getPixel(x,y);
pixel.y = ...
pixel.u = ...
pixel.v = ...
Also if another format would be faster please let me know.
If you look at the Image class you will see the immediate answer is simply the .getPlanes() method.
Of course, for YUV_420_888 this will yield three planes of YUV data which you will have to do a bit of work with in order to get the pixel value at any given location, because the U and V channels have been downsampled and may be interlaced in how they are stored in the Image.Planes. But that is beyond the scope of this question.
Also, you are correct that YUV will be the fastest available output for your camera. JPEG require extra time for encoding which will slow down the pipeline output, and RAW are very large and take a lot of time to read out because they are so large. YUV (of whatever type) is the data format that most camera pipelines work in so it is the 'native' output, and thus the fastest.
I am trying to implement a camera app, but it looks only the onJepgTaken in PictureCallback can take a buffer, while onRaw and onPostView takes null. And getSupportedPictureFormats always returns 256, so no hope to get YUV directly. If this is the case, I guess if I want to process the large image after image taking, I can only get the jpeg decoder for processing.
Updated: seems NV16 is available in takepicture callback and even if YUV buffer is not available, libjpeg is still there for codec stuff.