When drawing an insert, you can add or delete pixels.

According to the query of paper network, it is possible to make the image clearer by adjusting the contrast without tampering with the original data, but it is impossible to increase or decrease the pixels.

Illustrations (including photos) contain information and express information that can be said to be beyond the reach of words in the same page. Illustration can hold a lot of information, which is one of the important reasons why the author is willing to use it widely.