1 files changed, 154 insertions, 0 deletions
diff --git a/html/download/proc_fourier.cpp b/html/download/proc_fourier.cpp
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+/* IM 3 sample that calculates the Forward FFT, 
+  process in the domain frequency, 
+  and calculates the Inverse FFT.
+
+  Needs "im.lib" and "im_fftw.lib".
+
+  Usage: proc_fourier <input_file_name> <output_file_name> <output_format>
+
+    Example: proc_fourier test.tif test_proc.tif TIFF
+*/
+
+#include <im.h>
+#include <im_image.h>
+#include <im_process.h>
+#include <im_convert.h>
+#include <im_complex.h>
+
+#include <stdio.h>
+
+void FreqDomainProc(imImage* fft_image)
+{
+  // a loop for all the color planes
+  for (int d = 0; d < fft_image->depth; d++)
+  {
+    imcfloat* data = (imcfloat*)fft_image->data[d];
+
+    for (int y = 0; y < fft_image->height; y++)
+    {
+      for (int x = 0; x < fft_image->width; x++)
+      {
+        // Do something
+        // Remeber that the zero frequency is at the center
+        int offset = y * fft_image->width + x;
+
+        data[offset].imag = 0; // notice in the result that the imaginary part has an important hole.
+      }
+    }
+  }
+}
+
+void PrintError(int error)
+{
+  switch (error)
+  {
+  case IM_ERR_OPEN:
+    printf("Error Opening File.\n");
+    break;
+  case IM_ERR_MEM:
+    printf("Insuficient memory.\n");
+    break;
+  case IM_ERR_ACCESS:
+    printf("Error Accessing File.\n");
+    break;
+  case IM_ERR_DATA:
+    printf("Image type not Suported.\n");
+    break;
+  case IM_ERR_FORMAT:
+    printf("Invalid Format.\n");
+    break;
+  case IM_ERR_COMPRESS:
+    printf("Invalid or unsupported compression.\n");
+    break;
+  default:
+    printf("Unknown Error.\n");
+  }
+}
+
+imImage* LoadImage(const char* file_name)
+{
+  int error;
+  imFile* ifile = imFileOpen(file_name, &error);
+  if (!ifile) 
+  {
+    PrintError(error);
+    return 0;
+  }
+  
+  imImage* image = imFileLoadImage(ifile, 0, &error);  // load the first image in the file.
+  if (!image)
+    PrintError(error);
+    
+  imFileClose(ifile);  
+
+  return image;
+}
+
+void SaveImage(imImage* image, const char* file_name, const char* format)
+{
+  int error;
+  imFile* ifile = imFileNew(file_name, format, &error);
+  if (!ifile)
+  {
+    PrintError(error);
+    return;
+  }
+  
+  error = imFileSaveImage(ifile, image);
+  if (error != IM_ERR_NONE)
+    PrintError(error);
+
+  imFileClose(ifile);  
+}
+
+int main(int argc, char* argv[])
+{
+  if (argc < 4)
+  {
+    printf("Invalid number of arguments.\n");
+    return 0;
+  }
+
+  // Loads the image from file
+  imImage* image = LoadImage(argv[1]);
+  if (!image)
+    return 0;
+
+  // Creates a new image similar of the original but with complex data type.
+  // FFTW does not requires that the image size is a power of 2.
+  imImage* fft_image = imImageCreate(image->width, image->height, image->color_space, IM_CFLOAT);
+  if (!image)
+    return 0;
+
+  // Forward FFT
+  imProcessFFTW(image, fft_image);
+
+  // The user processing
+  FreqDomainProc(fft_image);
+
+  // The inverse is still a complex image
+  imImage* ifft_image = imImageClone(fft_image);
+  if (!image)
+    return 0;
+
+  // Inverse FFT
+  imProcessIFFTW(fft_image, ifft_image);
+
+  // Converts the complex image to the same type of the original image 
+  // so we can reuse its buffer
+  // (usually will be a bitmap image so we can also view the result)
+  if (image->data_type != IM_CFLOAT)
+  {
+    // This function will scan for min and max values before converting the data type
+    // There wiil be no gamma conversion, use abssolute values, and only the real part will be considered.
+    imConvertDataType(ifft_image, image, IM_CPX_REAL, IM_GAMMA_LINEAR, 1, IM_CAST_MINMAX);
+  }
+
+  SaveImage(image, argv[2], argv[3]);
+
+  imImageDestroy(image);
+  imImageDestroy(fft_image);
+  imImageDestroy(ifft_image);
+
+  return 1;
+}