I have a camera app, in it's simplest state it's nothing more then the cameraPreview example with some 'takePicture' code. The link to the example online is for 2.0, and i'm developping against 1.5 (API lvl 3), but still, here it is: http://developer.android.com/resources/samples/ApiDemos/src/com/example/android/apis/graphics/CameraPreview.html
The biggest difference with the old version is the whole "getOptimalPreviewSize" thing.
Everything is done landscape.
Now the problem is: i have a preview, but when i take the picture there is more information on that picture then there is on the preview. The top and bottom show stuff that wasn't visible on the preview.
Now i am going to put an overlay on top of the preview, to align the object in the picture with something. If the picture is taken, the whole thing gets squeezed a bit, and i'm all out of alignment :(.
The camera app on the system doesn't have this problem, so it must be possible to fix this. Any thoughts?
If i must manually set the preview and/or picture size, i'll have trouble with different handsets i guess, and because there are a lot of function only since API lvl 5 (e.g.: getOptimalPreviewSize), I can't use these.
Having built a custom camera app for Android, I know exactly what you are going through. Android 1.5 makes up only 1.1% of the Android users as of 10/29/2011. You will be better off jumping up to at least API level 5. If you want to support portrait and landscape previews consistently on all devices, I recommend you go even higher.
Make use of the getSupportedPreviewSizes() and getSupportedPicturesSizes(). These functions tell you exactly what the camera supports (varies by phone/manufacturer). Run through the enumerations and find values that match from both. Use the one that suits you best.
Word of warning: Failure to set preview and picture sizes that are actually supported can cause your app to crash on certain devices. I've seen this first hand.
reference to 1.5 Android users
The largest preview size returned by getSupportedPicturSizes represents the native resolution of your camera. If the aspect ratio of that size differs from your preview size or the picture size that you set your Camera object to then then cropping will occur. You can compare the aspect ratios to determine how much will be cropped and in which direction.(top/bottom vs left/right)
Related
I have tried writing my own code for accessing camera via the camera2 API on Android instead of using the Google's example. On one hand, I've wasted way too much time understanding what exactly is going on, but on the other hand, I have noticed something quite weird:
I want the camera to produce vertical images. However, despite the fact that the ImageReader is initialized with height larger than width, the Image that I get in the onCaptureCompleted has the same size, except it is rotated 90 degrees. I was struggling trying to understand my mistake, so I went exploring Google's code. And what I have found is that their images are rotated 90 degrees as well! They compensate for that by setting a JPEG_ORIENTATION key in the CaptureRequestBuilder (if you comment that single line, the images that get saved will be rotated). This is unrelated to device orientation - in my case, screen rotation is disabled for the app entirely.
The problem is that for the purposes of the app I am making I need a non-compressed precise data from camera, so since JPEG a) compresses images b) with losses, I cannot use it. Instead I use the YUV_420_888 format which I later convert to a Bitmap. But while the JPEG_ORIENTATION flag can fix the orientation for JPEG images, it seems to do nothing for YUV ones. So how do I get the images to be correctly rotated?
One obvious solution is to rotate the resulting Bitmap, but I'm unsure what angle should I rotate it by on different devices. And more importantly, what causes such strange behavior?
Update: rotating the Bitmap and scaling it to proper size takes way too much time for the preview (the context is as follows: I need both high-res images from camera to process and a downscaled version of these same images in preview. Let's just say I'm making something similar to QR code recognition). I have even tried using RenderScripts to manipulate the image efficiently, but this is still too long. Also, I've read here that when I set multiple output surfaces simultaneously, the same resolution will be used for all of them, which is quite bad for me.
Android stores every image, no matter if it is taken in landscape or in portrait, in landscape mode. It also stores metadata that tells you if the image should be displayed in portrait or landscape.
If you don'r turn the image according to the metadata, you will end up with every image in landscape. I had that problem too (but I wanted compression so my solution doesn't work for you).
You need to read the metadata and turn it accordingly.
I hope this helps at least a bit.
I am trying to capture a high resolution frame (1280x720) from the camera in a pair of Google Glass using OpenCV 2.4.10 for Android. I have implemented the CameraBridgeViewBase.CvCameraViewListener2 in my Activity and try to grab the frame in the onCameraFrame method. So far everything works well, and i get a 512x288 Mat object.
My problem is that the 512x288 resolution is not high enough for what I need. So I tried to setup my project the same way as they do in Sample 3 that follows with OpenCV: http://goo.gl/iDyqQj. The problem is that it only works for resolutions below 512x288, as soon as I increase the resolution above this level it defaults back to to being 512x288 (without any notice).
I found some suggestions, http://goo.gl/X2wtM4, that OpenCV is restricting the frame size to a maximum of the screen resolution. But the Google Glass screen should have a 640x360 resolution? I tried to do as described in the answer, but when I override calculateCameraFrameSize and return a Size-object larger than 512x288, I get a distorted frame (but with the larger dimensions, see below).
Does anyone have a suggestion on how capture a higher captured resolution on the Google Glass using OpenCV?
So I found a solution. It seem to be two separate problems. As I thought in my question you need to override calculateCameraFrameSize in JavaCameraView to be able to fetch higher resolutions than the device's screen in onCameraFrame. This is apparently a design choice by OpenCV and have been since version 2.4.5. So this is why I could not get a frame with higher resolution.
Even though I now can get a frame with higher resolution, it still is distorted for most preview sizes. This is a bug in the GDK that seem to have been known for quite some time (since XE10 if I understood correctly), but still is not fixed. Fortunately there is a workaround! The issue is avoided by manually setting the FPS of the preview using setPreviewFpsRange after you acquire the Camera.
Camera.Parameters params = camera.getParameters();
params.setPreviewFpsRange(30000, 30000);
camera.setParameters(params);
I have an app that I am working on that makes use of the front-facing camera on the device. I am trying to set the preview size by getting the list of supported preview sizes and looping through them looking for one that is pretty close. The method that I wrote to do so is basically the same as the one from the OS's own camera app. The method works fine, exactly how I would like it to, that's not why I am here.
I was having problems with the camera preview looking obviously skewed on some devices; either squishing or stretching the preview of the image. I couldn't figure out why it was doing this so I stepped through it and looked at all of the supported preview sizes available to my front-facing camera and found that there were only 2 and neither of them were the correct aspect to be usable. My "surfaceChanged" method in my SurfaceHolder.Callback class is reporting a width and height of 762x480 for the front-facing camera, but of the two supported preview sizes (acquired with cam.getParameters().getSupportedPreviewSizes()) both were in the opposite aspect: 480x800, 320x640.
With these as the only options, it seems impossible to have a preview for my front-facing camera that is not skewed. I know that in versions 2.3 or less, arbitrary values can be used for width and height without regard to supported sizes, but I am trying to make my app work for newer versions of the OS as well. How can I make the preview look correct?
My initial question remains technically unsolved (and I still believe it to be impossible) however I did figure out the trick to a non-skewed preview.
Given the supported preview sizes all being in the incorrect orientation compared to my device's screen it does indeed seem impossible to have a normal preview that fills the entire screen. After looking at several native camera apps on different devices (all of which that display the front-facing preview with no skewing at all) I noticed that very few of the devices (only one, in fact, and that one had a non-standard screen size) had previews that covered the entire screen as I was attempting to do in my app.
I reworked my app to get the size with the closest width and height to the device screen, but without going over in either dimension or in aspect ratio, and then manually set the height and width of the SurfaceView to match the selected size. True there is a small amount of black space around the preview on some devices now, but it definitely looks much better than being skewed. I had a panel with buttons for snapping a picture and manipulating flash settings, etc. on one side anyways, so it really is less noticeable than one might think.
I'm trying to develop an app for Android, and I would need to get uncompressed pictures with a resolution as high as possible from the camera. I tried takePicture's rawCallback and postviewCallback, but they are not working.
Right now I'm trying with OpenCV (version 2.4) using VideoCapture, but I'm stuck in the default 960x720, which is poor for what I need; and my phone, a Samsung Galaxy S3, is able to provide, theoretically, up to 8Mpx (3,264×2,448 for pictures, and 1,920×1,080 for video, according to Wikipedia). VideoCapture.set(Highgui.CV_CAP_PROP_FRAME_WIDTH/HEIGHT, some number) makes the camera return a black image as far as I've found.
Is there any way to obtain a higher resolution, either through OpenCV or with the Android API, without compressing?
I'm really sorry if this has been asked before; I have been looking for days and I have found nothing.
Thank you for your time!
EDIT: Although it is not exactly what I was asking, I found that there is a way to do something very similar: if you set an OnPreviewCallback for the Camera, using setPreviewCallback, you do get the raw picture data from the camera (at least in the S3 I'm working with). I leave it here in case somebody finds it useful in the future.
EDIT: A partial solution is explained in an answer below. To sum up,
vc.set(Highgui.CV_CAP_PROP_FRAME_WIDTH, desiredFrameWidth);
vc.set(Highgui.CV_CAP_PROP_FRAME_HEIGHT, desiredFrameHeight);
works under some conditions; please see below for further detail.
You have to get supported camera preview resoultions by calling getSupportedPreviewSizes.
After this you can set any resolution with method setPreviewSize. And don't forget to setParameters in the end. Actally many OpenCV Android examples contain this information (look at sample3).
In case anybody ever finds this useful, I found a (partial) solution: If your VideoCapture variable is called vc, this should work:
vc.set(Highgui.CV_CAP_PROP_FRAME_WIDTH, desiredFrameWidth);
vc.set(Highgui.CV_CAP_PROP_FRAME_HEIGHT, desiredFrameHeight);
Mind that the combination of width and height must be one of the supported picture formats for your camera, otherwise it will just get a black image. You can get those through Camera.Parameters.getSupportedPictureSizes().
However, setting a high resolution appears to exceed the YUV conversion buffer's capacity, so I'm still struggling with that. I'm going to make a new separate question for that, to keep everything clearer: new thread
setPreviewSize does not set picture resolution. setPictureSize does.
I changed the zxing code a little bit so in CaptureActivity.java, Bitmap barcode can be returned to my main app through an intent (I encode the bitmap using base64 and pass a string for the intent). Anyways, the problem is that barcode has a very low resolution and I'm trying to figure out if it's possible to return the preview picture (barcode) with a higher resolution (or have the width and height be greater then the preview frame).
Thanks
Sure you can do this if the device supports a preview resolution later than the screen. The app will already do this as of tthe latest version and use a little more resolution this way. Note that the LG Optimus has a notorious bug that will prevent it from working if you do this.
You don't want tto make the reticle larger or it will induce the user to hold the barcode too close to focus.