Every now and then I'm grading students and catch a case of plagiarism. Often, some part of the work stands out because it's better than what the student normally does. Usually, I just take a screenshot of the suspicious part, remove any clutter around it and reverse Google it. If I'm not successful and still have doubts, I'll try with the flipped image. Also, sometimes I'll add a keyword or two along with the image and it does the job.
I was checking an image today and had tons of hits of similar images. I had a feeling that the cropping really made a difference but I didn't have the original, just a modified flattened version of what I think might be plagiarized.
I ended up asking the student for their original image. I figured it looks bad if they are not willing to provide it...
Are there other tricks which can be leveraged to help with reverse searching an image?