In my last post, I use real image block data to test the DCT transform. Using this data, we can check the advantage of using DCT for image coding. Here is our first test data. By following code, we can get the inverse result of DCT transform. [code lang=“python”] # inverse transform, calculate the S by coefficients & basis S_inverse = np.zeros([N, N]) for k in range(0, 2): for j in range(0, 2): S_inverse = S_inverse + T[k][j]*U[k][j] [/code]

Last Post I have written The Basis Patterns of DCT and iDCT Transform – Part 1 as 1D array’s DCT transform. Now I try to produce the result of 2D matrix, which is usually used in Image & video processing. When reading Iain E. Richardson’s book: The H.264 Advanced Video Compression Standard, 2nd edition, there are 4x4 DCT basis patterns & 8x8 DCT basis patterns on page 45. And beyond this book, these patterns come out almost at every book about Image Processing or Video Coding technology.

Last post I have written about DCT and iDCT transform of a 2D image which is also a 2D matrix. There is a A matrix which is used to calculate DCT transform Y of original matrix X. The A is provided by the book directly, but how A is calculated out? Today I will talk about the original of matrix A. This is the first part of the topic which will focus on 1D vector transform.

Recently, I re-read Iain E. Richardson’s book: The H.264 Advanced Video Compression Standard, 2nd edition. I always focused on the theoretically part of the book and never pay attention to the detail of the calculation. But today I hit upon to check calculation of the book using Python for fun. The first part of the calculation I tried to check is about DCT which is printed on page 43-48. And I found that there maybe a mistake of figure 3.

Once when I updating my Windows 10, I restart my computer by accident. The update doesn’t finish and I try to re-update it again but failed. I get the Error Code 0x80070570. The solution is very simple: go to C:\Windows\SoftwareDistribution\Download and delete the folder called like this: dbaba752a8aa7203217c758502d7fddd