Discrete Cosine Transform help

1. Break an image-pixel array down into smaller blocks, e.g. 8 × 8 (or 16 × 16) pixels,
2. perform a discrete cosine transform (dct) on these smaller blocks,
3. apply a mask, consisting of an 8 × 8 array of zeros and ones, using array multiplication on the above dct block in order to eliminate certain high-frequency components,
4. use the inverse discrete cosine transform (idct) to reconstruct 8 × 8 image blocks, and
5. reassemble the blocks into a new image.Create your own function based on this script that will use 8×8 blocks, and will acceptthe name and type of an image together with a matrix representing the mask as input arguments2. I have looked at the ex from mathworks but it hasn't helped much. Any help would be greatly appreciated

[Azzi Abdelmalek]

And what is your question?

[Seth]

I do not even know where to start. #5 is where the prompt is

Answer 1

[Image Analyst]

To reassemble a matrix from two matrices, just stitch them together:

wideMatrix = [m1, m2];
tallMatrix = [m1; m2];

Put that into a loop where you make sure you change m1 and m2 so that they're the appropriate matrices for that location in the larger matrix you're assembling.

[Image Analyst]

Seth's "Answer" moved here since it's a question to me, not an answer to his original question above:

How would you put the matrices in a loop to where I am changing m1 and m2. Sorry I am new to image processing

[Image Analyst]

Let's say your blocks are in a cell array. Then you can do

for col = 1 : columns
  % Stitch the blocks together vertically.
  for row = 1 : rows
      thisBlock = cellArray{row, column};
      if row == 1
          thisVerticalBand = thisBlock;
      else
          thisVerticalBand = [thisRow; thisBlock];
      end
  end
  % Now we have a vertical band of the image.
  % Append it horizontally onto the prior bands.
  if col == 1
      outputImage = thisVerticalBand;
  else
      outputImage = [outputImage, thisVerticalBand];
  end
end

Or something like that. I hope you already know how to use the debugger to step through code. This is just untested, off the top of my head.