21. One or more non-transitory computer-readable media maintaining instructions executable by one or more processors to perform operations comprising: obtaining an image including text; identifying one or more text components in the image by analyzing pixels of the image to identify neighboring pixels that share at least one pixel property within a threshold range of values for the at least one pixel property; determining a legibility of individual ones of the identified text components by: generating a gray-level histogram based at least in part on the individual text component; and generating a confidence level for the legibility of an individual text component based at least in part on at least one of a first number of a bin of the gray-level histogram, a last number of a bin of the gray level histogram; or a difference between the first bin number and the last bin number; and comparing the confidence level with a legibility threshold, the legibility threshold based at least in part on a determined legibility of one or more images of training data used to train a classifier; classifying, based at least on the determining the legibility of the individual ones of the text components, the image as illegible; and sending a message indicating that the image has been determined to be illegible.
27. The one or more non-transitory computer-readable media of claim 21 , wherein the operations further comprise removing the content item from a library that is available to one or more users.