In the Swedish photo magazine Kamera & Bild you could read the following about Copyright for pictures.

“”Can I change a picture, and then publish it without the author's permission?

You may not change an image without the author's permission. It is an infringement of the non-profit right where the author has the right to decide how the image is transmitted to the public.

Can I change a picture a lot so that it almost becomes a new image, and then publish it without the author's permission?

It is only when you have changed the image into unrecognizable from what it first looked like it could possibly be considered that you have created a new work and thus have not infringed copyright. Otherwise, you must always have the author's permission”.