Legal pitfalls.
A legal pitfall connected to editing and using graphics is copyright. If someone has created a drawing, logo or movie then they have the copyright to these creations. If someone else uses the image without the creators permission then this is a breach of the copyright.
Even if the image colour or resolution is changed, It is still not a different image therefore in breach of the copyright.
Another legal pitfall connected to editing and using graphics is plagiarism. Plagiarism is the practice of taking someone else's work and claiming it as your own.
Trademark infringement is when the rights of a trademark are violated due to the unauthorized use of the trademarked logo or product. The only way to get around this is to get authorization from the owner.