Colour correct on digital image of watercolour painting.

I have a high-resolution scan of a watercolour painting that lost some of its subtlety in the process. A faint pinkish cast has crept into every area that should read as clean, nuanced white—both in the paper background and within the lighter passages of the subject itself... (Budget: £20 - £250 GBP, Jobs: Color Grading, Digital Art, Graphic Design, Illustrator, Image Analysis, Image Processing, Photo Editing, Photoshop, Photoshop Design, Visual Arts)