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//*********************************************************************************** // // File name: MimFFT.cs // Location: See Matrox Example Launcher in the MIL Control Center // // // Synopsis: This program uses the Fast Fourier Transform to filter an image. //*********************************************************************************** using System; using System.Collections.Generic; using System.Text; using Matrox.MatroxImagingLibrary; namespace MImFFT { class Program { // Target image specifications. private const string NOISY_IMAGE = MIL.M_IMAGE_PATH + "noise.mim"; private const int IMAGE_WIDTH = 256; private const int IMAGE_HEIGHT = 256; private const int X_NEGATIVE_FREQUENCY_POSITION = 63; private const int X_POSITIVE_FREQUENCY_POSITION = 191; private const int Y_FREQUENCY_POSITION = 127; private const int CIRCLE_WIDTH = 9; static void Main(string[] args) { MIL_ID MilApplication = MIL.M_NULL; // Application identifier. MIL_ID MilSystem = MIL.M_NULL; // System identifier. MIL_ID MilDisplay = MIL.M_NULL; // Display identifier. MIL_ID MilImage = MIL.M_NULL; // Image buffer identifier. MIL_ID MilOverlayImage = MIL.M_NULL; // Overlay image buffer identifier. MIL_ID MilSubImage00 = MIL.M_NULL; // Child buffer identifier. MIL_ID MilSubImage01 = MIL.M_NULL; // Child buffer identifier. MIL_ID MilSubImage10 = MIL.M_NULL; // Child buffer identifier. MIL_ID MilSubImage11 = MIL.M_NULL; // Child buffer identifier. MIL_ID MilTransformReal = MIL.M_NULL; // Real part of the transformed image. MIL_ID MilTransformIm = MIL.M_NULL; // Imaginary part of the transformed image. float[] ZeroVal = new float[1]; ZeroVal[0] = 0.0F; // Allocate defaults. MIL.MappAllocDefault(MIL.M_DEFAULT, ref MilApplication, ref MilSystem, ref MilDisplay, MIL.M_NULL, MIL.M_NULL); // Allocate a display buffer and clear it. MIL.MbufAlloc2d(MilSystem, IMAGE_WIDTH * 2, IMAGE_HEIGHT * 2, 8 + MIL.M_UNSIGNED, MIL.M_IMAGE + MIL.M_PROC + MIL.M_DISP, ref MilImage); MIL.MbufClear(MilImage, 0L); // Display the image buffer and prepare for overlay annotations. MIL.MdispSelect(MilDisplay, MilImage); MIL.MdispControl(MilDisplay, MIL.M_OVERLAY, MIL.M_ENABLE); MIL.MdispInquire(MilDisplay, MIL.M_OVERLAY_ID, ref MilOverlayImage); // Allocate child buffers in the 4 quadrants of the display image. MIL.MbufChild2d(MilImage, 0, 0, IMAGE_WIDTH, IMAGE_HEIGHT, ref MilSubImage00); MIL.MbufChild2d(MilImage, IMAGE_WIDTH, 0, IMAGE_WIDTH, IMAGE_HEIGHT, ref MilSubImage01); MIL.MbufChild2d(MilImage, 0, IMAGE_HEIGHT, IMAGE_WIDTH, IMAGE_HEIGHT, ref MilSubImage10); MIL.MbufChild2d(MilImage, IMAGE_WIDTH, IMAGE_HEIGHT, IMAGE_WIDTH, IMAGE_HEIGHT, ref MilSubImage11); // Allocate processing buffers. MIL.MbufAlloc2d(MilSystem, IMAGE_WIDTH, IMAGE_HEIGHT, 32 + MIL.M_FLOAT, MIL.M_IMAGE + MIL.M_PROC, ref MilTransformReal); MIL.MbufAlloc2d(MilSystem, IMAGE_WIDTH, IMAGE_HEIGHT, 32 + MIL.M_FLOAT, MIL.M_IMAGE + MIL.M_PROC, ref MilTransformIm); // Load a noisy image. MIL.MbufLoad(NOISY_IMAGE, MilSubImage00); // Print a message on the screen. Console.Write("\nFFT:\n"); Console.Write("----\n\n"); Console.Write("The frequency spectrum of a noisy image will be computed to remove the periodic noise.\n"); Console.Write("Press <Enter> to continue.\n\n"); Console.ReadKey(); // The image is Fourier transformed to obtain the magnitude of the // spectrum. This result will be used to design the filter. MIL.MimTransform(MilSubImage00, MIL.M_NULL, MilTransformReal, MilTransformIm, MIL.M_FFT, MIL.M_FORWARD + MIL.M_CENTER + MIL.M_MAGNITUDE + MIL.M_LOG_SCALE); MIL.MbufCopy(MilTransformReal, MilSubImage10); // Draw circles in the overlay around the points of interest. MIL.MbufCopy(MilTransformReal, MilSubImage11); MIL.MgraColor(MIL.M_DEFAULT, MIL.M_COLOR_YELLOW); MIL.MgraArc(MIL.M_DEFAULT, MilOverlayImage, X_NEGATIVE_FREQUENCY_POSITION, Y_FREQUENCY_POSITION + IMAGE_HEIGHT, CIRCLE_WIDTH, CIRCLE_WIDTH, 0, 360); MIL.MgraArc(MIL.M_DEFAULT, MilOverlayImage, X_POSITIVE_FREQUENCY_POSITION, Y_FREQUENCY_POSITION + IMAGE_HEIGHT, CIRCLE_WIDTH, CIRCLE_WIDTH, 0, 360); MIL.MgraArc(MIL.M_DEFAULT, MilOverlayImage, X_NEGATIVE_FREQUENCY_POSITION + IMAGE_WIDTH, Y_FREQUENCY_POSITION + IMAGE_HEIGHT, CIRCLE_WIDTH, CIRCLE_WIDTH, 0, 360); MIL.MgraArc(MIL.M_DEFAULT, MilOverlayImage, X_POSITIVE_FREQUENCY_POSITION + IMAGE_WIDTH, Y_FREQUENCY_POSITION + IMAGE_HEIGHT, CIRCLE_WIDTH, CIRCLE_WIDTH, 0, 360); // Put zero in the spectrum where the noise is located. MIL.MbufPut2d(MilSubImage11, X_NEGATIVE_FREQUENCY_POSITION, Y_FREQUENCY_POSITION, 1, 1, ZeroVal); MIL.MbufPut2d(MilSubImage11, X_POSITIVE_FREQUENCY_POSITION, Y_FREQUENCY_POSITION, 1, 1, ZeroVal); // Compute the Fast Fourier Transform of the image. MIL.MimTransform(MilSubImage00, MIL.M_NULL, MilTransformReal, MilTransformIm, MIL.M_FFT, MIL.M_FORWARD + MIL.M_CENTER); // Filter the image in the frequency domain. MIL.MbufPut2d(MilTransformReal, X_NEGATIVE_FREQUENCY_POSITION, Y_FREQUENCY_POSITION, 1, 1, ZeroVal); MIL.MbufPut2d(MilTransformReal, X_POSITIVE_FREQUENCY_POSITION, Y_FREQUENCY_POSITION, 1, 1, ZeroVal); MIL.MbufPut2d(MilTransformIm, X_NEGATIVE_FREQUENCY_POSITION, Y_FREQUENCY_POSITION, 1, 1, ZeroVal); MIL.MbufPut2d(MilTransformIm, X_POSITIVE_FREQUENCY_POSITION, Y_FREQUENCY_POSITION, 1, 1, ZeroVal); // Recover the image in the spatial domain. MIL.MimTransform(MilTransformReal, MilTransformIm, MilSubImage01, MIL.M_NULL, MIL.M_FFT, MIL.M_REVERSE + MIL.M_CENTER + MIL.M_SATURATION); // Print a message. Console.Write("The frequency components of the noise are located in the center of the circles.\n"); Console.Write("The noise was removed by setting these frequency components to zero.\n"); Console.Write("Press <Enter> to end.\n\n"); Console.ReadKey(); // Free buffers. MIL.MbufFree(MilSubImage00); MIL.MbufFree(MilSubImage01); MIL.MbufFree(MilSubImage10); MIL.MbufFree(MilSubImage11); MIL.MbufFree(MilImage); MIL.MbufFree(MilTransformReal); MIL.MbufFree(MilTransformIm); // Free defaults. MIL.MappFreeDefault(MilApplication, MilSystem, MilDisplay, MIL.M_NULL, MIL.M_NULL); } } }