ManagedCuda.NPP.NPPImage_8uC3.WarpPerspective C# (CSharp) Method

NPPImage_8uC3 Class Documentation Show file Open project: kunzmi/managedCuda

WarpPerspective() public static method

Perspective transform of an image. This function operates using given transform coefficients that can be obtained by using nppiGetPerspectiveTransform function or set explicitly. The function operates on source and destination regions of interest. The perspective warp function transforms the source image pixel coordinates (x,y) according to the following formulas: X_new = (C_00 * x + C_01 * y + C_02) / (C_20 * x + C_21 * y + C_22) Y_new = (C_10 * x + C_11 * y + C_12) / (C_20 * x + C_21 * y + C_22) The transformed part of the source image is resampled using the specified interpolation method and written to the destination ROI. The functions nppiGetPerspectiveQuad and nppiGetPerspectiveBound can help with destination ROI specification. NPPI specific recommendation: The function operates using 2 types of kernels: fast and accurate. The fast method is about 4 times faster than its accurate variant, but doesn't perform memory access checks and requires the destination ROI to be 64 bytes aligned. Hence any destination ROI is chunked into 3 vertical stripes: the first and the third are processed by accurate kernels and the central one is processed by the fast one. In order to get the maximum available speed of execution, the projection of destination ROI onto image addresses must be 64 bytes aligned. This is always true if the values (int)((void *)(pDst + dstRoi.x)) and (int)((void *)(pDst + dstRoi.x + dstRoi.width)) are multiples of 64. Another rule of thumb is to specify destination ROI in such way that left and right sides of the projected image are separated from the ROI by at least 63 bytes from each side. However, this requires the whole ROI to be part of allocated memory. In case when the conditions above are not satisfied, the function may decrease in speed slightly and will return NPP_MISALIGNED_DST_ROI_WARNING warning.

public static WarpPerspective ( NPPImage_8uC1 src0, NPPImage_8uC1 src1, NPPImage_8uC1 src2, NPPImage_8uC1 dest0, NPPImage_8uC1 dest1, NPPImage_8uC1 dest2, double coeffs, InterpolationMode eInterpolation ) : void
src0	NPPImage_8uC1	Source image (Channel 0)
src1	NPPImage_8uC1	Source image (Channel 1)
src2	NPPImage_8uC1	Source image (Channel 2)
dest0	NPPImage_8uC1	Destination image (Channel 0)
dest1	NPPImage_8uC1	Destination image (Channel 1)
dest2	NPPImage_8uC1	Destination image (Channel 2)
coeffs	double	Perspective transform coefficients [3,3]
eInterpolation	InterpolationMode	Interpolation mode: can be , or
return	void

        public static void WarpPerspective(NPPImage_8uC1 src0, NPPImage_8uC1 src1, NPPImage_8uC1 src2, NPPImage_8uC1 dest0, NPPImage_8uC1 dest1, NPPImage_8uC1 dest2, double[,] coeffs, InterpolationMode eInterpolation)
        {
            NppiRect rectIn = new NppiRect(src0.PointRoi, src0.SizeRoi);
            NppiRect rectOut = new NppiRect(dest0.PointRoi, dest0.SizeRoi);

            CUdeviceptr[] src = new CUdeviceptr[] { src0.DevicePointer, src1.DevicePointer, src2.DevicePointer };
            CUdeviceptr[] dst = new CUdeviceptr[] { dest0.DevicePointer, dest1.DevicePointer, dest2.DevicePointer };

            NppStatus status = NPPNativeMethods.NPPi.PerspectiveTransforms.nppiWarpPerspective_8u_P3R(src, src0.Size, src0.Pitch, rectIn, dst, dest0.Pitch, rectOut, coeffs, eInterpolation);
            Debug.WriteLine(String.Format("{0:G}, {1}: {2}", DateTime.Now, "nppiWarpPerspective_8u_P3R", status));
            NPPException.CheckNppStatus(status, null);
        }