Controlling Sensor ISO and Exposure time in android camera2API

Question

I am trying to add in Manual Camera Controls new exposure value and ISO values. I am using the Camera2Basic Example. The problem I face now is that I am new to Android. I tried looking at L-Camera but its in Scala and that confuses me further.

I tried the following changes but there was no update to the preview of the image.

 private void createCameraPreviewSession() {
    try {
        SurfaceTexture texture = mTextureView.getSurfaceTexture();
        assert texture != null;

        // We configure the size of default buffer to be the size of camera preview we want.
        texture.setDefaultBufferSize(mPreviewSize.getWidth(), mPreviewSize.getHeight());

        // This is the output Surface we need to start preview.
        Surface surface = new Surface(texture);

        // We set up a CaptureRequest.Builder with the output Surface.
        mPreviewRequestBuilder
                = mCameraDevice.createCaptureRequest(CameraDevice.TEMPLATE_PREVIEW);
        mPreviewRequestBuilder.addTarget(surface);

        // Here, we create a CameraCaptureSession for camera preview.
        mCameraDevice.createCaptureSession(Arrays.asList(surface, mImageReader.getSurface()),
                new CameraCaptureSession.StateCallback() {

                    @Override
                    public void onConfigured(@NonNull CameraCaptureSession cameraCaptureSession) {
                        // The camera is already closed
                        if (null == mCameraDevice) {
                            return;
                        }

                        // When the session is ready, we start displaying the preview.
                        mCaptureSession = cameraCaptureSession;
                        try {
                            // Auto focus should be continuous for camera preview.
                            mPreviewRequestBuilder.set(CaptureRequest.CONTROL_AF_MODE,
                                    CaptureRequest.CONTROL_AF_MODE_CONTINUOUS_PICTURE);

                            mPreviewRequestBuilder.set(CaptureRequest.CONTROL_AE_MODE,
                                    CaptureRequest.CONTROL_AE_MODE_OFF);

                            mPreviewRequestBuilder.set(CaptureRequest.SENSOR_EXPOSURE_TIME,Long.valueOf("100000"));
                            mPreviewRequestBuilder.set(CaptureRequest.SENSOR_SENSITIVITY,1600);

                            // Flash is automatically enabled when necessary.
                            setAutoFlash(mPreviewRequestBuilder);

                            // Finally, we start displaying the camera preview.
                            mPreviewRequest = mPreviewRequestBuilder.build();
                            mCaptureSession.setRepeatingRequest(mPreviewRequest,
                                    mCaptureCallback, mBackgroundHandler);
                        } catch (CameraAccessException e) {
                            e.printStackTrace();
                        }
                    }

                    @Override
                    public void onConfigureFailed(
                            @NonNull CameraCaptureSession cameraCaptureSession) {
                        showToast("Failed");
                    }
                }, null
        );
    } catch (CameraAccessException e) {
        e.printStackTrace();
    }
}

Answer 1

I also had problems with green captures when using manual exposure with camera 2 API. I could fix it by only deactivating CONTROL_AE_MODE instead of both CONTROL_AE_MODE and CONTROL_MODE. This is my configuration:

final CaptureRequest.Builder captureBuilder = cameraDevice.createCaptureRequest(CameraDevice.TEMPLATE_STILL_CAPTURE);

captureBuilder.set(CaptureRequest.CONTROL_AE_MODE, CameraCharacteristics.CONTROL_AE_MODE_OFF);
captureBuilder.set(CaptureRequest.CONTROL_MODE, CameraCharacteristics.CONTROL_MODE_AUTO);
captureBuilder.set(CaptureRequest.SENSOR_EXPOSURE_TIME, Long.valueOf("8000000")); // 8000000 ns = 8 ms

Answer 2

This will fix the problem:

mPreviewBuilder.set(
    CaptureRequest.CONTROL_AWB_MODE, 
    CaptureRequest.CONTROL_AWB_MODE_AUTO
);

Answer 3

So I have made the following changes to my code.

mPreviewRequestBuilder
    = mCameraDevice.createCaptureRequest(CameraDevice.TEMPLATE_MANUAL);
mPreviewRequestBuilder.addTarget(surface);


mPreviewRequestBuilder.set(CaptureRequest.CONTROL_MODE,
    CaptureRequest.CONTROL_MODE_OFF);

mPreviewRequestBuilder.set(CaptureRequest.CONTROL_AF_MODE,
    CaptureRequest.CONTROL_AF_MODE_CONTINUOUS_PICTURE);

mPreviewRequestBuilder.set(CaptureRequest.CONTROL_AE_MODE,
    CaptureRequest.CONTROL_AE_MODE_OFF);

mPreviewRequestBuilder.set(CaptureRequest.SENSOR_EXPOSURE_TIME,Long.valueOf("22000"));
mPreviewRequestBuilder.set(CaptureRequest.SENSOR_SENSITIVITY,200);

mCaptureSession.setRepeatingRequest(mPreviewRequest,
    mCaptureCallback, mBackgroundHandler);

However I get a weird preview with a lot of green light taken as an input.

Here it is https://postimg.org/image/yl95e6qht/

This is what it looks like using my inbuilt camera app: https://postimg.org/image/lvjnwquj5/

Answer 4

First, you must change your template to TEMPLATE_STILL_CAPTURE or TEMPLATE_MANUAL to see the values change in the preview. Also, remember to set your CONTROL_AE_MODE and 'CONTROL_MODE' to OFF.

This control is only effective if android.control.aeMode or android.control.mode is set to OFF; otherwise the auto-exposure algorithm will override this value.

From Android Developer

Second, set your values with:

builder.set(CaptureRequest.SENSOR_SENSITIVITY, isoValue);
builder.set(CaptureRequest.SENSOR_EXPOSURE_TIME, exposureTimeValueInMilliseconds);

Finally after all the changes don't forget to update your preview using a CaptureSession.setRepeatingRequest

Hope it will help you!