MimFFT
This program uses the Fast Fourier Transform to filter an image.
Language: C++
Functions used: MappAlloc, MappFree, MbufAlloc2d, MbufChild2d, MbufClear, MbufCopy, MbufFree, MbufLoad, MbufPut2d, MdispAlloc, MdispControl, MdispFree, MdispInquire, MdispSelect, MgraArc, MimTransform, MsysAlloc, MsysFree
Categories: Overview, General, Industries, Electronics, Applications, Preprocessing, Modules, Buffer, Display, Graphics, Image Processing, What's New, Older
///////////////////////////////////////////////////////////////////////////////
// Aurora Imaging Library
// Filename: MImFFT.cpp
//
// Description: This program uses the Fast Fourier Transform to filter an image.
//
// (C) 1992-2026 Zebra Technologies Corp. and/or its affiliates
// All Rights Reserved
///////////////////////////////////////////////////////////////////////////////
#include <AIL.h>
#include <math.h>
// Target image specifications.
#define NOISY_IMAGE M_IMAGE_PATH AIL_TEXT("noise.mim")
#define IMAGE_WIDTH 256
#define IMAGE_HEIGHT 256
#define X_NEGATIVE_FREQUENCY_POSITION 63
#define X_POSITIVE_FREQUENCY_POSITION 191
#define Y_FREQUENCY_POSITION 127
#define CIRCLE_WIDTH 9
int MosMain(void)
{
AIL_ID AilApplication, // Application identifier.
AilSystem, // System identifier.
AilDisplay, // Display identifier.
AilImage, // Image buffer identifier.
AilOverlayImage, // Overlay image buffer identifier.
AilSubImage00, // Child buffer identifier.
AilSubImage01, // Child buffer identifier.
AilSubImage10, // Child buffer identifier.
AilSubImage11, // Child buffer identifier.
AilTransformReal, // Real part of the transformed image.
AilTransformIm; // Imaginary part of the transformed image.
float ZeroVal = 0.0;
// Allocate defaults.
MappAllocDefault(M_DEFAULT, &AilApplication, &AilSystem, &AilDisplay,M_NULL, M_NULL);
// Allocate a display buffer and clear it.
MbufAlloc2d(AilSystem, IMAGE_WIDTH*2, IMAGE_HEIGHT*2,
8+M_UNSIGNED, M_IMAGE+M_PROC+M_DISP, &AilImage);
MbufClear(AilImage, 0L);
// Display the image buffer and prepare for overlay annotations.
MdispSelect(AilDisplay, AilImage);
MdispControl(AilDisplay, M_OVERLAY, M_ENABLE);
MdispInquire(AilDisplay, M_OVERLAY_ID, &AilOverlayImage);
// Allocate child buffers in the 4 quadrants of the display image.
MbufChild2d(AilImage, 0L, 0L, IMAGE_WIDTH, IMAGE_HEIGHT, &AilSubImage00);
MbufChild2d(AilImage, IMAGE_WIDTH, 0L,IMAGE_WIDTH, IMAGE_HEIGHT, &AilSubImage01);
MbufChild2d(AilImage, 0L, IMAGE_HEIGHT, IMAGE_WIDTH, IMAGE_HEIGHT, &AilSubImage10);
MbufChild2d(AilImage, IMAGE_WIDTH, IMAGE_HEIGHT, IMAGE_WIDTH, IMAGE_HEIGHT,
&AilSubImage11);
// Allocate processing buffers.
MbufAlloc2d(AilSystem, IMAGE_WIDTH, IMAGE_HEIGHT, 32+M_FLOAT,
M_IMAGE+M_PROC, &AilTransformReal);
MbufAlloc2d(AilSystem, IMAGE_WIDTH, IMAGE_HEIGHT, 32+M_FLOAT,
M_IMAGE+M_PROC, &AilTransformIm);
// Load a noisy image.
MbufLoad(NOISY_IMAGE, AilSubImage00);
// Print a message on the screen.
MosPrintf(AIL_TEXT("\nFFT:\n"));
MosPrintf(AIL_TEXT("----\n\n"));
MosPrintf(AIL_TEXT("The frequency spectrum of a noisy image will be computed ")
AIL_TEXT("to remove the periodic noise.\n"));
MosPrintf(AIL_TEXT("Press any key to continue.\n\n"));
MosGetch();
// The image is Fourier transformed to obtain the magnitude of the
// spectrum. This result will be used to design the filter.
MimTransform(AilSubImage00, M_NULL, AilTransformReal, AilTransformIm,
M_FFT, M_FORWARD+M_CENTER+M_MAGNITUDE+M_LOG_SCALE);
MbufCopy(AilTransformReal, AilSubImage10);
// Draw circles in the overlay around the points of interest.
MbufCopy(AilTransformReal, AilSubImage11);
MgraControl(M_DEFAULT, M_COLOR, M_COLOR_YELLOW);
MgraArc(M_DEFAULT, AilOverlayImage, X_NEGATIVE_FREQUENCY_POSITION,
Y_FREQUENCY_POSITION+IMAGE_HEIGHT, CIRCLE_WIDTH, CIRCLE_WIDTH, 0, 360);
MgraArc(M_DEFAULT, AilOverlayImage, X_POSITIVE_FREQUENCY_POSITION,
Y_FREQUENCY_POSITION+IMAGE_HEIGHT, CIRCLE_WIDTH, CIRCLE_WIDTH, 0, 360);
MgraArc(M_DEFAULT, AilOverlayImage, X_NEGATIVE_FREQUENCY_POSITION+IMAGE_WIDTH,
Y_FREQUENCY_POSITION+IMAGE_HEIGHT, CIRCLE_WIDTH, CIRCLE_WIDTH, 0, 360);
MgraArc(M_DEFAULT, AilOverlayImage, 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.
MbufPut2d(AilSubImage11, X_NEGATIVE_FREQUENCY_POSITION,
Y_FREQUENCY_POSITION, 1, 1, &ZeroVal);
MbufPut2d(AilSubImage11, X_POSITIVE_FREQUENCY_POSITION,
Y_FREQUENCY_POSITION, 1, 1, &ZeroVal);
// Compute the Fast Fourier Transform of the image.
MimTransform(AilSubImage00, M_NULL, AilTransformReal,
AilTransformIm, M_FFT, M_FORWARD+M_CENTER);
// Filter the image in the frequency domain.
MbufPut2d(AilTransformReal, X_NEGATIVE_FREQUENCY_POSITION,
Y_FREQUENCY_POSITION, 1, 1, &ZeroVal);
MbufPut2d(AilTransformReal, X_POSITIVE_FREQUENCY_POSITION,
Y_FREQUENCY_POSITION, 1, 1, &ZeroVal);
MbufPut2d(AilTransformIm, X_NEGATIVE_FREQUENCY_POSITION,
Y_FREQUENCY_POSITION, 1, 1, &ZeroVal);
MbufPut2d(AilTransformIm, X_POSITIVE_FREQUENCY_POSITION,
Y_FREQUENCY_POSITION, 1, 1, &ZeroVal);
// Recover the image in the spatial domain.
MimTransform(AilTransformReal, AilTransformIm,
AilSubImage01, M_NULL, M_FFT, M_REVERSE+M_CENTER+M_SATURATION);
// Print a message.
MosPrintf(AIL_TEXT("The frequency components of the noise are located ")
AIL_TEXT("in the center of the circles.\n"));
MosPrintf(AIL_TEXT("The noise was removed by setting these frequency ")
AIL_TEXT("components to zero.\n"));
MosPrintf(AIL_TEXT("Press any key to end.\n\n"));
MosGetch();
// Free buffers.
MbufFree(AilSubImage00);
MbufFree(AilSubImage01);
MbufFree(AilSubImage10);
MbufFree(AilSubImage11);
MbufFree(AilImage);
MbufFree(AilTransformReal);
MbufFree(AilTransformIm);
// Free defaults.
MappFreeDefault(AilApplication, AilSystem, AilDisplay, M_NULL, M_NULL);
return 0;
}