Develop Reference

Does mirroring the (front) camera affect MLKit with CameraX?

You might consider this question a sequel to this other one I've recently asked. I have a custom device with a front camera that is mirrored by default and I would like it to always behave like it was flipped horizontally. Note that the end goal of my app is to perform face, barcode and facemask detection (the last one with a custom .tflite model), and I'm trying to understand if it's possible with the current state of CameraX and the quirks of the device I'm using.
For the preview, I can force PreviewView to use a TextureView by calling PreviewView#implementationMode = PreviewView.ImplementationMode.COMPATIBLE so I can just call PreviewView#setScaleX(-1) and it gets displayed like I want.
For taking pictures, I haven't tried yet but I know I can pass setReversedHorizontal(true) to the ImageCapture.OutputFileOptions used in the ImageCapture.Builder, so the image should be saved in reverse.
For image analysis I really don't know. If the input image is taken directly from the preview stream, then it should still be in its default state because PreviewView#setScaleX(-1) only flips the View on screen, right? So in my Analyzer's analyze() I would need to convert the ImageProxy#image to bitmap, then flip it and pass the result to InputImage.fromBitmap().
Is this everything I need? Is there a better way to do this?

How to set android camera2 parameters to have the best result at text recognizing

I'm creating an android app that allow user to scan the code on a small card (like yu gi oh card).
The problem is that the number I want to read is really small and it's hard to get a good focus to make it clear. So I wanted to set the params to get the best result at closest distance.
At first, I follow this tutorial to create a simple camera preview: https://inducesmile.com/android/android-camera2-api-example-tutorial/
Next I tried to change the camera preview settings to disable auto-focus, it works well, but then I tried to manually set the focus distance, and nothing change.
This is an extract of the code in the camera preview creation methods :
CameraManager manager = (CameraManager) getSystemService(Context.CAMERA_SERVICE);
CameraCharacteristics characteristics = manager.getCameraCharacteristics(cameraId);
//Disable auto-focus
captureRequestBuilder.set(CaptureRequest.CONTROL_AF_MODE, CameraMetadata.CONTROL_AF_MODE_OFF);
//Try to make it at the shortest distance (do not work)
captureRequestBuilder.set(CaptureRequest.LENS_FOCUS_DISTANCE, characteristics.get(CameraCharacteristics.LENS_INFO_MINIMUM_FOCUS_DISTANCE)
I've tried different parameters on the focus distance, but nothing change.
Maybe I'm just making a mistake, and it's not the right way to improve this.

Manual focus control is not a guaranteed feature. Many lower-end devices do not support it, and only support autofocus. You can check if the device has the capability MANUAL_SENSOR. Some cameras are entirely fixed-focus (mostly these are selfie cameras), so those you can't even autofocus.
For your use case, autofocus should work well enough anyway, as long as the small card fills up most of the visible scene.
Note that many devices have a minimum focus distance of 8-10 cm, so you can't hold the card really close and expect to get sharp images of it.

Android Camera2: Auto Focus and Exposure

In my Android camera application I'm using the Camera2 API. The application doesn't show the preview of the Camera, and I've implemented it in a way, when a button on the UI is pressed, it takes an image. But the problem is with auto focus and auto exposure. Simply, I need to camera always focused on the middle of its view. So when building the request, I added following properties:
captureBuilder.set(CaptureRequest.CONTROL_AF_MODE, CaptureRequest.CONTROL_AF_MODE_AUTO);
captureBuilder.set(CaptureRequest.CONTROL_AE_MODE, CaptureRequest.CONTROL_AE_MODE_ON);
captureBuilder.set(CaptureRequest.CONTROL_AWB_MODE, CaptureRequest.CONTROL_AWB_MODE_AUTO);
captureBuilder.set(CaptureRequest.CONTROL_AF_TRIGGER, CameraMetadata.CONTROL_AF_TRIGGER_START);
captureBuilder.set(CaptureRequest.CONTROL_AE_PRECAPTURE_TRIGGER, CameraMetadata.CONTROL_AE_PRECAPTURE_TRIGGER_START);
But the problem is still the images are not focused.
I have couple of questions:
Do I need to implement some checking in a method inside CameraCaptureSession.CaptureCallback?
I also noticed that by the time onImageAvailable is called in ImageReader.OnImageAvailableListener, the onCaptureProgressed method of CameraCaptureSession.CaptureCallback is not triggered.
What are the points I'm missing here? Do I need to implement a thread to wait until the camera is focused, which will start by when pressing the take picture button.
Please note that there's no camera preview for this application.

Are you sending only a single capture request? Or are you running a repeating request in the background, and then only issuing a high-resolution capture on button press?
The former won't really work - you have to have a flow of requests to have the autoexposure, focus, and white balance algorithms converge to good values. A single capture won't be properly metered or focused.
Please take a look at the Camera2Basic sample; if you replace the TextureView in that sample with just a SurfaceTexture (give it a random texture ID and don't call updateTexImage), then you can have no preview. But it implements focusing and the precapture trigger correctly, which is critical for you here. For one, the triggers must only be set on one request, and then you do need to watch the capture results coming back to see when the exposure / focus state changes to FOCUSED or CONVERGED.
I'd also recommend the CONTINUOUS_PICTURE focus mode instead of AUTO; it's likely to get you a focused image faster.

sketch effect or cartoon effect to camera in android

I saw an app called Cartoon Camera .
https://play.google.com/store/apps/details?id=com.fingersoft.cartooncamera
I was wondering how to add effect to camera directly. I know how to add effect after the picture is taken or to a bitmap. But how to do it in real time camera.
I have no idea on how to start this. Please give me some ideas so I can start the project.

Android OS delivers a built in native filters, their official names are ColorEffects and you an set them easily. The drawback is that you need to implement your own camera in order to use it(Or download android camera from git).
If you just want to use external camera you can find out if the camera broadcast supports color effect.
Then, you can get all the color effects of the camera by doing:
mParameters.getSupportedColorEffects();
It will return a list of supported color effect, but be aware that also some of the effects are exist in this list - you cannot select them because they are being used as part of a scene so in order to apply them you need also to set the exposure, saturation and more.
The ColorEffects that doesn't based on a scene can be easily apply by the following lines of code:
mParameters.setColorEffect(effect);
try {
mCameraDevice.setParameters(mParameters);
} catch (Exception e) {
}

Android blur surfaceview used in camera

I have a camera preview in my android app. As you all probably know it is implemented by a surfaceview in android.
In my photo app, which allows users to take pictures, I want to blur the camera preview (the surface view) if the user has not logged in yet if the user is logged in, I will display the normal preview (without blur)
Blur as something like
But there seems to be no way to do it
Couple things come to mind but I am not sure how to achieve it
use a blur overlay and place it on top of the surface view, but how do u create such blur overlay?
another approach is to change the attribute of the window, but I can't do it to surfaceview,
getWindow().addFlags(WindowManager.LayoutParams.FLAG_BLUR_BEHIND);
So can we create a window overlay the surfaceview and set the flag like that? I don't think so
can someone tell me how to blur a camera preview, which is a surface view
note: I am trying to blur an area which is the output from camera preview, so it is not like I am blurring a static image, the blur area will change depending on where you point your phone camera

The best way to do this is to take a screen shot of the control, apply a blur to it, and then show that image over the top of the original control. This is how the yahoo weather app does it and its how google suggest you do things like this.
Render script does bluring fast. I've also got some code, but it's not currently at hand right now.
These might help:
http://blog.neteril.org/blog/2013/08/12/blurring-images-on-android
http://docs.xamarin.com/recipes/android/other_ux/drawing/blur_an_image_with_renderscript/
I've also read that there are methods built into Android that do this, but the API isn't public so we cannot use it... which sucks.

Although your 2nd option is losing support in later versions of the Android OS, it may be a good option. I would think to bring a window IN FRONT of your surfaceview, and use the blur_behind property of your now new IN FRONT window.
Android API documentation
"
This constant was deprecated in API level 14.
Blurring is no longer supported.
Window flag: blur everything behind this window.
Constant Value: 4 (0x00000004)"
I do have to admit, Im not 100% sure this would work, but its definitely worth a try.

You have to change the camera parameters; in this case with Camera.Parameters.setPictureSize().
The basic workflow here is :
Camera.Parameters cp = mCamera.getParameters(); // get the current params
cp.set...(); // change something
mCamera.setParameters(cp); // write the params back
Make sure that every resolution that you set via this function is supported. You can get a list of the resolutions that are supported on a device via Camera.Parameters.getSupportedPictureSizes(). and check this Camera documentation.