Images, like other documents, can be scholarly or not--and for the same reasons. Here is what makes an image scholarly:
Though Google Image Search is the easiest way to find a broad group images, it’s probably the worst. This is because the images that people use on commercial websites or blogs are frequently altered, have no clear ownership, or are of poor quality. It’s often impossible to know if they’re legitimate or who you can go to for permissions.
The University Library has more than 200 databases that contain searchable scholarly images. Always start with authentic images so you will never need to backtrack or be frustrated about getting permissions.
Once you have an image, there are several ways to test it. Al these are interrelated.
Image originality - is this the first time and place this image has appeared?
Image metadata - did the site where you obtain the image from list the creator and/or photographer? Do they securely own the image?
Image quality - is the image sharp? Is the image at least 72 dpi? What is DPI?
Image size - Related to image quality. Is this the largest image available? [use a Google Reverse Image Search or TinEye to tell]
Scholarly images frequently come with full descriptions. After all, if an image is legitimate, its owners typically want the users to know that. Even in cases where citation is not required, it is considered ethical to cite the title, creator and location of an object
Citations help readers who may want to look up your image themselves. It also proves your own knowledge of the image.
Assume an image is copyrighted unless there is an explicit indication that it is copyright free.
People and institutions frequently claim ownership to images they don’t own.