Your painting is for sure great! Very smooth and precise.
But, I still think that the whole picture looks blue, rather than just the background. In some cameras the white balance has to be changed manually, try and take a picture of a pure white surface, and if it turns out blue, you'll have to change these settings. I hope this is helpful and that you don't see it as critique, I had this problem myself for a long time with my new camera before a friend told me what was the problem.