Discrete Cosine Transform?
Could someone explain how Discrete Cosine Transform (DCT) in image compression is used as simple as possible?
Best is to use Wikipedia, google etc, to get a synopsis of what DCT does.
For a full explanation, there are hundreds of monographs on the web.
However, the best way to comprehend what it does is 1) use a sheet of graph paper
2) create any image you can on paper
3) follow DCT algorithm to generate a block
4) then decompose that block.
You can see that the decomposed block does not exactly match the original, but it is close enough.
It is a "lossy" form of compression and saves a bunch of memory.
You take the 2-D DCT of the block, most of the coefficients are small and discarded, the large coefficients are retained and has a smaller file size than the original data that constituted the image.
When the image is reconstructed from the highest coefficients it will be a good representation of the original if enough coefficients have been retained.
The compression is lossy because information has been discarded.