Illustration essay is introduced in case of necessity to demonstrate visual type of information to a receiver. That does not necessarily means that the essay is not provided with verbal media. The text can be represented in a plane of references, explanatory thesis, indicating issues, lines of descriptive information, etc. Practically these are descriptive blocks of text.
As most receptors ignore detailed text information preferring it to next illustrative sources.
The distribution of illustrations through the text explains the controversial point of illustration essay writing when critics oppose that today it is text that is distributed through the images content.
The progress of informational media consumption explains this redistribution. It is not a secret that only about decades ago newspaper and journal style of publishing was different from what is displayed on the pages of any illustrative info media.
Who is a supervisor of images search, filtration and distribution is not really important if it all is not about unlicensed copying, distribution and illegal production of brutal images content. The essay producer is obligatory to get all necessary licenses for installation and distribution of the images no matter what type of media, newspaper (book, web-site, movie, video, etc.) is available for transmission of material.
If it is personal type essay the author has a right to introduce images of private content. In case of links occurrence from other media it is safe to put paroles on essay cover and provide the receiver with all needed extraction codes.