Black image captured instead of view from camera

[tiwarigaurav2044]

hey, i am using windows 64 bit and i am trying a simple capture image code but the it unable to capture an image. the captured image is attached

[sarxos]

Hi @tiwarigaurav2044,

It would be more helpful if you post more details, such as:

• source code,
• which Webcam Capture API version you are using,
• what is the camera (the model, vendor, etc),
• is there a problem with capture from e.g. Skype or other application?

[tiwarigaurav2044]

this is the source code:

Webcam.setAutoOpenMode(true);
Webcam webcam = Webcam.getDefault();
BufferedImage im = webcam.getImage();
ImageIO.write(im, "PNG", new File("D:\\test.png"));
webcam.close();

the version im using is 0.3.10
the webcam is inbuilt in my laptop
the webcam is fine if i use jframe for live video then it is working fine but its not able to capture an image

[sarxos]

@tiwarigaurav2044,

That's weird, however I never expect anything else from Windows :)

I suppose that this may be caused by the fact that camera buffer is empty at the very beginning. The Webcam Capture API automatically discard the first three frames that comes from the grabber (the buffer memory). This is happening in WebcamDefaultDevice.java line 360. I empirically verified that the camera buffer size is 5, but in all my experiments only the first frame was blank, so it's very weird why you're getting empty image (the 4'th frame from buffer).

This is in regards to the root cause, but later today I will provide you with the source code I would like you to execute to verify what is the number of first non-blank image you receive from camera. By knowing this we can fine-tune the number of frames that must be discarded and I can hopefully do small modification in the code to fix your problem.

[tiwarigaurav2044]

i got it thanks the first 2 images are blank but the 3rd image is fine. thanks a lot

[sarxos]

Ok, so it seems like all the 5 elements of initial camera buffer were empty. I will introduce the fix to discard all of them before the camera device is open.

[tiwarigaurav2044]

Is it possible to stream the live video feed onto any another device such as a smart phone through socket programing?

[sarxos]

Yes, this is possible. There is a video streaming proof-of-concent example that demonstrates how to transcode BuffereImage objects that comes from camera device into h.264 stream and access such stream remotely, but please bear in mind that Webcam Capture API has been designed to capture image from camera in the first place, and all the additional functionalities (like transcoding, streaming, etc) must be done with the 3'rd party frameworks.

[tiwarigaurav2044]

thanks i will look into it.

[sarxos]

I'm opening this ticket so I remember to fix that.

[sarxos]

@tiwarigaurav2044,

I implemented the change we were talking about. It should work fine now and all of the initial memory buffer elements should be removed so the black image should not appear any more. It is available in 0.3.11-SNAPSHOT.

Just FYI if you want to take a look, the @ryancheu fork of webcam-capture-live-streaming example is adding supports for additional audio streaming (source code at webcam-capture-live-streaming @ ryancheu).

[lenikhilsingh]

Hey iam using windows 10 64 bit ,i have two webcam 1.) inbuild laptop webcam 2.) usb webcam.
my buffered image is fetching black images from my usb webcam, but the same code is working fine with laptop inbuild webcam. Here's my code @sarxos
`

public class WebCamController implements Initializable {
Webcam webcam;
Preferences preference= Preferences.getPreferences();
boolean isRunning = false;

@FXML
private ImageView imageHolder;
@FXML
private Label displayDir;
@FXML
private Button button;
@FXML
private JFXTextField id1;
AlertMaker alert;



@Override
public void initialize(URL url, ResourceBundle rb) {
    webcam = Webcam.getWebcams().get(0);
    webcam.setViewSize(new Dimension(320,240));
    webcam.open();
    new VideoFeedTaker().start();
    final Tooltip buttonTooltip =new Tooltip();
    buttonTooltip.setText("Capture Image");
    button.setTooltip(buttonTooltip);
    
}  
public void setText(String recID){
    this.id1.setText(recID);
    System.out.println("+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++"+id1.getText());
}


class VideoFeedTaker extends Thread {
    
    @Override
    public void run(){
        while(!isRunning){
            BufferedImage image = webcam.getImage();
             if(image == null){
                 break;
             }else{
                WritableImage image1 = SwingFXUtils.toFXImage(image, null);
                imageHolder.setImage(image1);
             }
            try {
                Thread.sleep(42);
            } catch (InterruptedException ex) {
                Logger.getLogger(WebCamController.class.getName()).log(Level.SEVERE, null, ex);
            }
        }
    }
}

@FXML
private void captureImage(ActionEvent event) throws IOException {
    BufferedImage image = webcam.getImage();
    if(image == null){
        System.out.println("this image is null please");
    }else{
        WritableImage image1 = SwingFXUtils.toFXImage(image, null);
        imageHolder.setImage(image1);
    }
    String path = System.getProperty("user.home")+"\\Documents\\camImage\\"+id1.getText()+".jpeg";
    File outputFile = new File(path);
    outputFile.getParentFile().mkdirs();
    ImageIO.write(image, "JPEG", outputFile);
    System.out.println(System.getProperty("user.home"));
    displayDir.setText(path);
    
    if(!isRunning){
        isRunning = true;
        new VideoFeedTaker().start();
    }else{
        isRunning = false;
    }
}

}`

Using javafx and java 8 (IDE netbeans 8.2).