How can I modify the size at which images in the media library are displayed when viewing the media library?
I use a function to disable generation/modification of images, and manually edit to 750x250px then upload.
When viewing the media library, I want them to display in this rectangular format (although smaller than actual) rather than the default square.
settings -> media
. There add your required resolution either for Medium or for large and save changes. If you have change resolution for Medium option then On upload of image there is an option appear on right side to select size of image (thumbnail, medium, large etc). Choose medium and you will get your desire resolution. See if that helps.