there is no sort of hidden optimization and the Prototyper should present your UI applicaton exactly as it appears on the target.
I assume that you have done some adaptations in order run the UI application on a LPC32xx device, correct? Can you ensure that the LCD is displaying the colors correctly and that it is connected correctly from hardware point of view?
You can check this by displaying some color gradients:
How does it appear on your target?
Btw: What color format are you using?