An explanation regarding "copy", "trace", and "reference" -- originally posted on:
http://www26.atwiki.jp/yunomip/pages/18.html
(the author gives free permission to re-post this image)
1. Original
2. Copy and paste
3. Modified
4.Trace
5. Trace a part
6. Copy with drawing
7. Reference
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The following discription on "Art Plagiarism" is written by sacredflamingheart (@Deviant Art)
http://sacredflamingheart.deviantart.com/journal/What-Is-Art-Plagiarism-READ-THIS-234951828
"But, don't be fooled--just like it's art theft to combine multiple images into one image, it's art plagiarism to combine multiple "references" into a single piece. Identically copying any major element of another person's work is still art theft. (More on alluding to other works later.) If you were to give your character a keyblade that looks identical to Sora's, that's art plagiarism. You didn't make that design."
"You must have explicit permission from the original creator of a piece in order to use it in any way that you can claim as your own."
"It does NOT excuse your theft just to say that "referencing" the entirety of one picture for your own picture is "an homage to the original," or that the original "inspired you" to make the exact same piece, "only different." (More on identical reproductions later.)"
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phardil Yes, there is a DIFFERENCE between being inspired by someone and plagiarism. In your case, it is NOT inspiration, it is not even referencing.
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Yes, there are millions of other artists who uses professional artists' works for study purposes -- not copying others' works and claim it is original.
If it is an exercise for you, you should note on your image that it is an exercise/copy based on other artists (and what picture you have studied from), not just put your © on it and claim it is your original work. It is not.
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Just because others are doing it, doesn't make it the right thing to do.