I'm currently putting together a CD cover, and haven't been working that much with printing, so CMYK tends to confuse me a bit.
I'm going to place a logo inside a frame in InDesign. I added the exact same background color to the logo in Photoshop, as the background color of my InDesign document. Still the background in InDesign is slightly darker when I export the PDF as I look at it on screen (if I look at it from different angles).
Any ideas? I use the following black for both: C: 75% M: 68% Y: 67% K: 90%
You can also see that when I'm watching two version of my PDF (with transparent PSD placed in InDesign), it gets a white line around the cut area if I zoom it in or out. If I look at it in 'actual size', it looks normal.