Entropy. Take a colored pixel. It is connected to a four other pixels each could be one of say 256 colors but are more likely likely to be a shade similar to each other. So you have roughly 1000 options. But then take a given English word. How many possible words might come after the word "the"? The set of possible connections between words in a paragraph are larger than the set of possible pixel colors in a given image (a realworld image, not white noise/static/random pixels.)