With the release of the iPhone in 2007, the trend in interface graphics turned the majority of designs dimensional. Every object morphed into an imitation of the physical space, gaining highlights, shdows, texture and dimension. Backgrounds became soft gradients. The illusion of space, artificially created by visual tricks, became the norm for our interactive world.
The 2013 release of the iPhone officially catches it up with what other interfaces have been moving to already... flat design. And now this aesthetic has been quickly trickling into corporate sites and communications.
To successfully implement a flat color design, designers and marketers need to take a closer look at hue. In the world of bubbly objects and shadows, hue (commonly referred to as color) is pretty forgiving as the eye can pick out the most pleasing shade. If you take the same colors and turn them into flat graphics, you no longer have the highlights and shadows that make the object 'pop' off the background and become visible. The hues butt up against one another and you're left with only color relationships to create visibility.
In order to ensure enough contrast is present to see and read objects well, it's important to take a closer look at the contrast created between the two colors. In the example above, the background was adjusted to a cooler gray, and the colors were shifted to a lighter, mintier hue to increase contrast.
The best thing to remember when shifting your brand to flat graphics is that color is completely relational.