camera roll desaturates image loaded from email

Being a professional photographer using a DSLR and new to Instagram I am having some issues. Right now I email my image to my iPhone but when I push it through to my "Camera Roll" the visual quality of the image changes—it desaturates it. Am I doing something wrong?

Does anyone have experience of using dropbox to bring images from an iMac to an iPhone camera roll? Cheers, jp