OpenCv Kotlin diff. and int. using 1D kernel

// OpenCV Kotlin calc differentiation and integration of an image using custom 1D kernels
// note that the first row/col of image is NOT differentiated
// -- this is on purpose to restore the original image

// prepare for derivative and integration
val image16 = Mat()
image.convertTo(image16, CvType.CV_16SC3)
image.release()

// make derivative kernels
val dxKernel = Mat(1, 2, CvType.CV_16SC1)
val dxAnchor = Point(1.0, 0.0)
dxKernel.put(0, 0, shortArrayOf(-1, 1))

val dyKernel = Mat(2, 1, CvType.CV_16SC1)
val dyAnchor = Point(0.0, 1.0)
dyKernel.put(0, 0, shortArrayOf(-1, 1))

// differentiate
val dxImage = Mat()
Imgproc.filter2D(image16, dxImage,  -1, dxKernel, dxAnchor, 0.0, Core.BORDER_CONSTANT)

val dyImage = Mat()
Imgproc.filter2D(image16, dyImage, -1, dyKernel, dyAnchor, 0.0, Core.BORDER_CONSTANT)

// do something with the dxyImage here


// make integral kernels
val dxSize = dxImage.size().width.toInt()
val ixKernel = Mat(1, dxSize, CvType.CV_16SC1)
val ixAnchor = Point(dxSize.minus(1).toDouble(), 0.0)
ixKernel.put(0, 0, ShortArray(dxSize) {1})

val dySize = dyImage.size().height.toInt()
val iyKernel = Mat(dySize, 1, CvType.CV_16SC1)
val iyAnchor = Point(0.0, dySize.minus(1).toDouble())
iyKernel.put(0, 0, ShortArray(dySize) {1})

// integrate
val ixImage = Mat()
Imgproc.filter2D(dxImage, ixImage, -1, ixKernel, ixAnchor, 0.0, Core.BORDER_CONSTANT)
dxImage.release()

val iyImage = Mat()
Imgproc.filter2D(dyImage, iyImage, -1, iyKernel, iyAnchor, 0.0, Core.BORDER_CONSTANT)
dyImage.release()

// do something with the ixyImage here


// release integral images
ixImage.release()
iyImage.release()