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'*********************************************************************************** ' ' File name: MimFFT.vb ' Location: See Matrox Example Launcher in the MIL Control Center ' ' ' Synopsis: This program uses the Fast Fourier Transform to filter an image. '*********************************************************************************** Imports Microsoft.VisualBasic Imports System Imports System.Collections.Generic Imports System.Text Imports Matrox.MatroxImagingLibrary Namespace MImFFT Friend Class Program ' Target image specifications. Private Const NOISY_IMAGE As String = MIL.M_IMAGE_PATH & "noise.mim" Private Const IMAGE_WIDTH As Integer = 256 Private Const IMAGE_HEIGHT As Integer = 256 Private Const X_NEGATIVE_FREQUENCY_POSITION As Integer = 63 Private Const X_POSITIVE_FREQUENCY_POSITION As Integer = 191 Private Const Y_FREQUENCY_POSITION As Integer = 127 Private Const CIRCLE_WIDTH As Integer = 9 Shared Sub Main(ByVal args() As String) Dim MilApplication As MIL_ID = MIL.M_NULL ' Application identifier. Dim MilSystem As MIL_ID = MIL.M_NULL ' System identifier. Dim MilDisplay As MIL_ID = MIL.M_NULL ' Display identifier. Dim MilImage As MIL_ID = MIL.M_NULL ' Image buffer identifier. Dim MilOverlayImage As MIL_ID = MIL.M_NULL ' Overlay image buffer identifier. Dim MilSubImage00 As MIL_ID = MIL.M_NULL ' Child buffer identifier. Dim MilSubImage01 As MIL_ID = MIL.M_NULL ' Child buffer identifier. Dim MilSubImage10 As MIL_ID = MIL.M_NULL ' Child buffer identifier. Dim MilSubImage11 As MIL_ID = MIL.M_NULL ' Child buffer identifier. Dim MilTransformReal As MIL_ID = MIL.M_NULL ' Real part of the transformed image. Dim MilTransformIm As MIL_ID = MIL.M_NULL ' Imaginary part of the transformed image. Dim ZeroVal(0) As Single ZeroVal(0) = 0.0F ' Allocate defaults. MIL.MappAllocDefault(MIL.M_DEFAULT, MilApplication, MilSystem, MilDisplay, CType(MIL.M_NULL, IntPtr), CType(MIL.M_NULL, IntPtr)) ' 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, 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, MilOverlayImage) ' Allocate child buffers in the 4 quadrants of the display image. MIL.MbufChild2d(MilImage, 0, 0, IMAGE_WIDTH, IMAGE_HEIGHT, MilSubImage00) MIL.MbufChild2d(MilImage, IMAGE_WIDTH, 0, IMAGE_WIDTH, IMAGE_HEIGHT, MilSubImage01) MIL.MbufChild2d(MilImage, 0, IMAGE_HEIGHT, IMAGE_WIDTH, IMAGE_HEIGHT, MilSubImage10) MIL.MbufChild2d(MilImage, IMAGE_WIDTH, IMAGE_HEIGHT, IMAGE_WIDTH, IMAGE_HEIGHT, MilSubImage11) ' Allocate processing buffers. MIL.MbufAlloc2d(MilSystem, IMAGE_WIDTH, IMAGE_HEIGHT, 32 + MIL.M_FLOAT, MIL.M_IMAGE + MIL.M_PROC, MilTransformReal) MIL.MbufAlloc2d(MilSystem, IMAGE_WIDTH, IMAGE_HEIGHT, 32 + MIL.M_FLOAT, MIL.M_IMAGE + MIL.M_PROC, MilTransformIm) ' Load a noisy image. MIL.MbufLoad(NOISY_IMAGE, MilSubImage00) ' Print a message on the screen. Console.Write(Constants.vbLf + "FFT:" + Constants.vbLf) Console.Write("----" + Constants.vbLf + Constants.vbLf) Console.Write("The frequency spectrum of a noisy image will be computed to remove the periodic noise." + Constants.vbLf) Console.Write("Press <Enter> to continue." + Constants.vbLf + Constants.vbLf) 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." + Constants.vbLf) Console.Write("The noise was removed by setting these frequency components to zero." + Constants.vbLf) Console.Write("Press <Enter> to end." + Constants.vbLf + Constants.vbLf) 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) End Sub End Class End Namespace