modified
There is a technical word to define the modifications a painter can bring to his works, those changes are called “repentances”. Usually, instead of taking the colour off, artists use to cover the mistake and draw it again according to new parameters (they could be dictated by technical reasons, but also by those who commissioned the painting). It is rare to be able to see repentances with the naked eye, as in this case. On the contrary, they are usually visible through an X-ray analysis of the picture. Repentances are usually considered as a guarantee for the authenticity of a painting (somebody who intended to copy a picture would not need to make changes to its structure).