How to convert BufferedImage to IplImage?

[Stephan Beuze]

I'm trying to detect some images on the screen. Here is my code:

// Get screen size

Rectangle fullScreenRectangle = new Rectangle(Toolkit.getDefaultToolkit().getScreenSize());

// Capture screen 

BufferedImage screenshot = new Robot().createScreenCapture(fullScreenRectangle);

// Convert BufferedImage into IplImage

Java2DFrameConverter frameBufferedImageConverter = new Java2DFrameConverter();

OpenCVFrameConverter.ToIplImage frameIplImageConverter = new OpenCVFrameConverter.ToIplImage(); 

 

Frame screenshotFrame = frameBufferedImageConverter.convert(screenshot);

IplImage screenshotIplImage = frameIplImageConverter.convert(screenshotFrame);

          // Use JavaCV to match template with captured screen ...

I'm getting this error:

java.lang.ClassCastException: java.nio.DirectByteBuffer cannot be cast to java.nio.IntBuffer

I searched and find this patch: https://github.com/bytedeco/javacv/commit/918c7540482a87be6b6c83b10abad660b551c140

So I started using the Java2DFrameConverter patched version and I still can't capture the screen.

Here is what I expect...

... and this is what I get:

What am I doing wrong?

[Samuel Audet]

On 06/28/2015 03:59 PM, Stephan Beuze wrote:
> What am I doing wrong?

Probably nothing, there's some more fixes here:
https://github.com/bytedeco/javacv/commit/487954e1cb1e4dabfa74f7ff698dc2331259365d

Samuel

[Samuel Audet]

Actually, I've tried your code, and Robot returns images in ARGB format:

BufferedImage@179d3b25: type = 1 DirectColorModel: rmask=ff0000
gmask=ff00 bmask=ff amask=0 IntegerInterleavedRaster: width = 3200
height = 1080 #Bands = 3 xOff = 0 yOff = 0 dataOffset[0] 0

That's not going to work very well with OpenCV. We can convert that to,
for example, BGRA, which works much better with OpenCV, this way:

IplImage bgraImage = IplImage.create(screenshotIplImage.width(),
screenshotIplImage.height(), IPL_DEPTH_8U, 4);
cvMixChannels(screenshotIplImage, 1, bgraImage, 1, new int[] {0,3,
1,2, 2,1, 3,0}, 4);

Samuel

[Stephan Beuze]

Thanks for your replies Samuel.

Is it planned to add the additions below to Java2DFrameConverter ?

[Samuel Audet]

Not really, it would cause inconsistencies with other image formats. Besides, it's more efficient to use FFmpeg to capture from the screen these days...

Samuel

2015/07/09 6:21 "Stephan Beuze" <sbe...@gmail.com>:

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[Samuel Audet]

Actually, there is already functionality for that. Calling
Java2DFrameConverter.getBufferedImage(frame, 1.0, true, null) should
produce the same result.

Samuel