For example, I have inserted a purple rectangle into my InDesign document, on top of this I have placed a solid white PSD file of a hoover with a transparent background.
When working in InDesign, you are not able to differentiate between the outline of the graphic and the purple rectangle - they look seamless and the hoover just looks like a simple white graphic on top of the rectangle. However, after exporting to PDF and printing, the box in which I placed the hoover seems to be a different shade of purple! Any ideas why this could happen?
The pictures don't show it all that well, but I can ensure you that it's easy to spot on hard copies!!