CODEWITHSUNDEEP
javaopencvjframe
user4429422
user4429422

Reputation:

Java OpenCV convert HSV back to BGR after inRange

I'd like to create a black&white image relying on HSV filtering. However, after converting the image from BGR to HSV and applying the inRange() method, the matrix is reduced to a single channel matrix (with values either 0 or 255) and cannot be converted back to BGR.

Is there an easy way to work around this? Do I even need that step of back-conversion or can I somehow display the new image with the information I have? I'm pretty new to OpenCV and already found a very similar question but I'm still kinda confused on what to do.

Example:

System.loadLibrary(Core.NATIVE_LIBRARY_NAME);
Mat img = Imgcodecs.imread(path);
Mat hsv = new Mat();
Mat img_new = new Mat(); 

Imgproc.cvtColor(img,hsv,Imgproc.COLOR_BGR2HSV);
Core.inRange(hsv, new Scalar(hue,saturation,value),new Scalar(hue,saturation,value),hsv);
Imgproc.cvtColor(hsv, img_new, Imgproc.COLOR_HSV2BGR); // This line doesn't work.

// display new image in JFrame
MatOfByte mob = new MatOfByte();
Imgcodecs.imencode(".tif", img_new, mob);
byte ba[] = mob.toArray();
BufferedImage bi = ImageIO.read(new ByteArrayInputStream(ba));
newImgLabel.setIcon(new ImageIcon (bi));

Thank you in advance!

Upvotes: 1

Views: 949

Answers (1)

unlut
unlut

Reputation: 3775

inRange function gives you a mask(actually, a single channel image with values 0 and 255), you can use it to select which areas you want to select.

Mat mask = new Mat();
Imgproc.cvtColor(img,hsv,Imgproc.COLOR_BGR2HSV);
Core.inRange(hsv, new Scalar(hue,saturation,value),new Scalar(hue,saturation,value),mask);
img.copyTo(img_new, mask);

Upvotes: 0

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