Slashdot Mirror

← Back to Stories (view on slashdot.org)

Ask Slashdot: How To Catch Photoshop Plagiarism?

Posted by timothy on from the when-google-images-isn't-enough dept.

First time accepted submitter jemenake writes "A friend of mine teaches electronic media (Photoshop, Premiere, etc.) at a local high-school. Right now, they're doing Photoshop, and each chapter in the book starts with an 'end result' file which shows what they're going to construct in that chapter, and then, given the basic graphical assets (background textures, photos, etc.), the students need to duplicate the same look in the final-result file. The problem, of course, is that some students just grab the final-result file and rename it and turn it in. Some are a little less brazen and they rename a few layers, maybe alter the colors on a few images, etc. So, it becomes time-consuming for her to open each file alongside the final-result file to see if it's 'too perfect.'" How to look for images closer than they should be to the original? Read on for more details. jemenake continues: "When I first discovered that she was doing this, my first reaction was that there's got to be some automated way of catching the cheaters. Of course, my first idea of just doing MD5 hashes of each file won't work, since most kids alter the file a little bit.

A second idea I had was to alter the final-result file in a way that isn't obvious, like removing someone's shoelace, mis-spelling a word in the background, or removing/adding some dust-specks. (I know map publishers and music transcribers use this trick to catch copiers). But this still requires that she look for the alteration in each file. I'd think that Photoshop, after all these years, would have some kind of scripting language which also supports some digital watermarking, but I've just never dabbled in that realm.

And, of course, I guess another solution would be for her to not provide the end-result file in Photoshop format, but to export it as a flat image. But I'm still intrigued by the notion of being able to "fuzzily" compare two photoshop files or images to find the ones which are too similar in certain aspects (color histograms, where the edges are, level of noise, whatever).

Anybody else have any clever ideas for this?"

14 of 284 comments (clear)

  1. Invent your own exercises by Anonymous Coward · · Score: 5, Insightful

    That's what a teacher is supposed to do anyway.

    1. Re:Invent your own exercises by im_thatoneguy · · Score: 1, Insightful

      Or view exercises for what they are... exercises. The test/final project is what it is. Maybe your students don't need the exercises because they already have a strong grasp of the task.

    2. Re:Invent your own exercises by Z00L00K · · Score: 5, Insightful

      It's of course easy to invent your own exercises, but even better would be to have the students to use pictures they have taken themselves to be used in the exercise. And almost everyone has a mobile phone with a camera these days so that would be a minor problem. Or provide a collection of pictures that can be used in the exercise and let them play around.

      Just state the basic points, then let each student do what they can and let them rate each others results. Don't force the students to use the same template, let them have their artistic freedom.

      And isn't the whole point behind the exercise to learn how to use Photoshop and other tools - not to try to mimic a creation?

      --
      If builders built buildings the way programmers wrote programs, then the first woodpecker would destroy civilization.
    3. Re:Invent your own exercises by Anonymous Coward · · Score: 2, Insightful

      (I am a music teacher, but want to add to the discussion from an arts perspective)

      Not every person in every discipline should re-invent the wheel at all times. Though as an expert (assumably) you should be coming up with your own material, there are other instances where there are resources which are as good as anything you'd put together on your own. Including assignments.

      In this case, however, I think there's an important consideration. Even if the primary focus is to learn Photoshop, this is an arts class. Instead of foisting my own opinions on you here, let's turn to artist, qualitative researcher and arts pedagogy expert Elliot Eisner, taken from a speech in 2008 entitled "What Education Can Learn from the Arts":

      "There’s so much at school where uniformity of outcome is the aspiration. In the arts it’s just the opposite, what you want is heterogeneity, you want diversity, you want idiosyncrasy. You don’t want 30 yellow ducks made by 30 kids in the 4th grade all looking alike. That’s an artistic, pedagogical disaster. ...See, a spelling teacher doesn’t want her students to be innovative. That’s not the location for it. That’s uniformity. In art, it’s just the opposite"

      So, though it's more work for the teacher and student, in this instance making your own assignment wherein students have to show they used all of the techniques they were taught while creating their own subject is not only a solution to avoid plagiarism but is also a more artistically sound education.

      m!

    4. Re:Invent your own exercises by j-beda · · Score: 4, Insightful

      Or require students to also hand in the intermediate steps for the homework just like old school math.

      At the start of the course have a discussion about ethics and expectations. Have a class discussion of the purpose of the exercises. Have the class participate in designing the evaluation scheme (percentages for HW, tests, etc.) Get them to buy into the course so they view it as something they are participating in because they see value in their participation. Have them turn in some intermediate steps, and maybe some commentary on things they found challenging or interesting about the activities.

      Record transgressors and use the policies of your institution to at the very least get it into their institutional record if they commit any accredited dishonesty so that if they have a pattern of that type of behaviour they can be tracked.

    5. Re:Invent your own exercises by shawn(at)fsu · · Score: 3, Insightful

      There are some good problems that have been asked over and over again because they teach good lessons. My data structures professor started one of our assignments off with the following quote "More time has been spent on undergraduates recreating the Ackerman function than any other problem in computer science, and you all will be no different"

      Sure there are other problems that have double recursion but why try to find something new and different when a good problem already exists? Plus there is something unifying about it. If I meet someone who graduated years before me or years after and they also had to do the Ackerman function in some language maybe the same one I used it kind of give you something in common. I like that; a common thread the ties us all together.

      --
      500 dollar reward for tip(s) leading to the arrest of the person(s) who stole my sig.
    6. Re:Invent your own exercises by egranlund · · Score: 3, Insightful

      Newsflash: Students usually cheat because they DON'T have a strong grasp of the task.

      Not necessarily. There are many reasons that people cheat:
      1) They are lazy
      2) They "don't have the time"
      3) They think they're getting away with something

      In these cases they use "I don't know how to do it" as the excuse to just cheat, rather than expend the effort required to ask for clarification or practice further until they do grasp the task/concept that they are performing.

      For some reason in college (at least my college), people cheating is totally normal and students talk about it like it's no big deal. To me, there is no purpose going to college if you're not going to do any of the work that would teach you something.

    7. Re:Invent your own exercises by jarbrewer · · Score: 5, Insightful

      On the grading machine, keep the history window open. It's stored as part of the file. File history should give a very good idea if the student is resorting to shenanigans. Yes, a student could delete the file's history, but the teacher could require 'showing your work' through the history.

  2. Final result should just be a flattened image? by Anonymous Coward · · Score: 4, Insightful

    Why not just flatten the final result into a simple image? The students can still see what the end result is supposed to look like, but they obviously can't just hand in that file.

  3. Don't Give Them The File? by Anonymous Coward · · Score: 2, Insightful

    How about simply not giving them the final file? Why not a printed copy?
    If they must have an electronic version of the picture give them a low res thumbnail version.
    Project the image on a screen and tell them to draw that.

    Your problem is that you are over thinking the tech angle when low tech methods will be super effective.

  4. Simple Solution by hubang · · Score: 4, Insightful

    The solution is simple:

    Give a token homework grade (like ~ 10%) for participating and make everything in the final grade else be based on original projects and tests. Make the students use given files.

    Then, if they cheat, they only cheat themselves.

  5. MOD PARENT UP! - Re:Final result should just be by corychristison · · Score: 5, Insightful

    Why not just flatten the final result into a simple image? The students can still see what the end result is supposed to look like, but they obviously can't just hand in that file.

    Offer flat JPG in medium quality as an "end result". Maybe even include a digital metadata watermark?

    Require high quality JPEG and PSD for assignment. First check for metadata watermark, then compare quality of JPEG. If it looks too close then open up the PSD and check the layers.

  6. Re:FindImageDupes by Anonymous Coward · · Score: 2, Insightful

    Given that the students are supposed to reproduce the images, I guess they will get a high visual similarity, unless they failed.

  7. Change the assignment by Mr.+Freeman · · Score: 3, Insightful

    For one thing, you can prevent plagiarism by not asking students for plagiarism. You're giving students a file and then asking them to duplicate it. That's pretty much the definition of plagiarism and, frankly, probably of very little educational benefit.

    The teacher needs to stop trying to figure out ways to catch people cheating on an exercise designed for cheating and start teaching the damn course. Teaching doesn't just mean lecturing and assigning exercises out of some book, it means developing exercises, homework problems, and exams from scratch as well.

    --
    -1 disagree is not a modifier for a reason. -1 troll, flaimbait, redundant, overrated are NOT acceptable substitutes.