Paper edge detection in camera view on android 12

[Egidijus Kuzma]

Firstly it's quite sad, that this library has been left unmaintained. Very compact, well writen library.

Starting android 12 paper edges are not shown on live camera view.
In image cropper edges are detected.

Maybe anyone has solved this issue?

[sujay-appringer]

@egidijus-kuzma have you found any solution i have the same issue.

[Egidijus Kuzma]

@egidijus-kuzma have you found any solution i have the same issue.

Yes, will post solution

[Mohit Kumar]

Hi @egidijus-kuzma
Can you share the solution with us? We are facing the same issue.

[Egidijus Kuzma]

Function ImageProxy.yuvToRgba() need to be overriden:

@SuppressLint("UnsafeOptInUsageError")
internal fun ImageProxy.yuvToRgba(): Mat {
    val rgbaMat = Mat()

    if (format == ImageFormat.YUV_420_888
        && planes.size == 3) {

        val planes: Array<Image.Plane> = image!!.getPlanes()
        val w: Int = image!!.getWidth()
        val h: Int = image!!.getHeight()
        val chromaPixelStride = planes[1].pixelStride


        if (chromaPixelStride == 2) { // Chroma channels are interleaved
            assert(planes[0].pixelStride == 1)
            assert(planes[2].pixelStride == 2)
            val y_plane = planes[0].buffer
            val y_plane_step = planes[0].rowStride
            val uv_plane1 = planes[1].buffer
            val uv_plane1_step = planes[1].rowStride
            val uv_plane2 = planes[2].buffer
            val uv_plane2_step = planes[2].rowStride
            val y_mat = Mat(h, w, CvType.CV_8UC1, y_plane, y_plane_step.toLong())
            val uv_mat1 = Mat(h / 2, w / 2, CvType.CV_8UC2, uv_plane1, uv_plane1_step.toLong())
            val uv_mat2 = Mat(h / 2, w / 2, CvType.CV_8UC2, uv_plane2, uv_plane2_step.toLong())
            val addr_diff = uv_mat2.dataAddr() - uv_mat1.dataAddr()
            if (addr_diff > 0) {
                assert(addr_diff == 1L)
                Imgproc.cvtColorTwoPlane(y_mat, uv_mat1, rgbaMat, Imgproc.COLOR_YUV2RGBA_NV12)
            } else {
                assert(addr_diff == -1L)
                Imgproc.cvtColorTwoPlane(y_mat, uv_mat2, rgbaMat, Imgproc.COLOR_YUV2RGBA_NV21)
            }

        } else { // Chroma channels are not interleaved
            val yuv_bytes = ByteArray(w * (h + h / 2))
            val y_plane = planes[0].buffer
            val u_plane = planes[1].buffer
            val v_plane = planes[2].buffer
            var yuv_bytes_offset = 0
            val y_plane_step = planes[0].rowStride
            if (y_plane_step == w) {
                y_plane[yuv_bytes, 0, w * h]
                yuv_bytes_offset = w * h
            } else {
                val padding = y_plane_step - w
                for (i in 0 until h) {
                    y_plane[yuv_bytes, yuv_bytes_offset, w]
                    yuv_bytes_offset += w
                    if (i < h - 1) {
                        y_plane.position(y_plane.position() + padding)
                    }
                }
                assert(yuv_bytes_offset == w * h)
            }
            val chromaRowStride = planes[1].rowStride
            val chromaRowPadding = chromaRowStride - w / 2
            if (chromaRowPadding == 0) {
                // When the row stride of the chroma channels equals their width, we can copy
                // the entire channels in one go
                u_plane[yuv_bytes, yuv_bytes_offset, w * h / 4]
                yuv_bytes_offset += w * h / 4
                v_plane[yuv_bytes, yuv_bytes_offset, w * h / 4]
            } else {
                // When not equal, we need to copy the channels row by row
                for (i in 0 until h / 2) {
                    u_plane[yuv_bytes, yuv_bytes_offset, w / 2]
                    yuv_bytes_offset += w / 2
                    if (i < h / 2 - 1) {
                        u_plane.position(u_plane.position() + chromaRowPadding)
                    }
                }
                for (i in 0 until h / 2) {
                    v_plane[yuv_bytes, yuv_bytes_offset, w / 2]
                    yuv_bytes_offset += w / 2
                    if (i < h / 2 - 1) {
                        v_plane.position(v_plane.position() + chromaRowPadding)
                    }
                }
            }
            val yuv_mat = Mat(h + h / 2, w, CvType.CV_8UC1)
            yuv_mat.put(0, 0, yuv_bytes)
            Imgproc.cvtColor(yuv_mat, rgbaMat, Imgproc.COLOR_YUV2RGBA_I420, 4)
        }


    }

    return rgbaMat
}

[sujay-appringer]

@egidijus-kuzma thank you!! this helped me a lot.