DCT is used in JPEG standard along with Huffman encoding to further compress the result. I understand that most of the data in spatial domain which is an image is "present in low frequencies". This is because most adjacent pixels change only little in the color value.
An image which is represented numerically in signal processing, with numbers representing the pixel color intensity. When we do a DCT on it we still get numbers in result. Where exactly does data get compressed via DCT?