In the case where there are purples in the image that you want to keep (as Gordon explained) you can use masks
It's really easy and cool to work with masks in photoshop.
With a mask you can add a layer above your original layer, then totally distort the copied layer. Remove a color (example remove purple) or whatever you would like to do, and then use the brush to paint in the mask to make the parts of the original image to come forward (or vise versa depending on how you order your layers).
Here is an example where i made a duplicate of the original layer and removed all blue color. Then i placed a mask on that layer and painted on the mask to make the original image to come forward.
Here is what it looks like in PS: