Blue Background Removal

[Larienas]

Hi Samuel,

  I following the instruction in the https://medium.com/fnplus/blue-or-green-screen-effect-with-open-cv-chroma-keying-94d4a6ab2743 to remove the blue background from an image

  I am not familiar with how to specify the values written below in Python and so the same 

lower_blue = np.array([0, 0, 100]) ##[R value, G value, B value]
upper_blue = np.array([120, 100, 255])

mask = cv2.inRange(image_copy, lower_blue, upper_blue)

masked_image[mask != 0] = [0, 0, 0]

in JavaCV to make it work. Could you please help

With Regards,

Lariena

[Samuel Audet]

With the C++ API, we can use Scalar objects:
http://bytedeco.org/javacpp-presets/opencv/apidocs/org/opencv/core/Core.html#inRange-org.opencv.core.Mat-org.opencv.core.Scalar-org.opencv.core.Scalar-org.opencv.core.Mat-

[Samuel Audet]

Actually, the C++ API doesn't use Scalar directly:
http://bytedeco.org/javacpp-presets/opencv/apidocs/org/bytedeco/opencv/global/opencv_core.html#inRange-org.bytedeco.opencv.opencv_core.Mat-org.bytedeco.opencv.opencv_core.Mat-org.bytedeco.opencv.opencv_core.Mat-org.bytedeco.opencv.opencv_core.Mat-

But it's possible to do something like this:
lower_blue = new Mat(new Scalar(...));
upper_blue = new Mat(new Scalar(...));
inRange(image_copy, lower_blue, upper_blue, mask)


Samuel