ARTDECO magazine.
It was an incoming 64 pages mock up made in MicroSoft PowerPoint. But our printing factory accepts only pdf-files. MicroSoft PowerPoint program works with RGB colour system. It's good for presentation but bad for printing.
I met following problems:
1. Wrong size (U.S. Letter page size, but customer expected A4 size)
2. RGB colour system (not CMYK)
3. There was Image's resolution from 72 ppi to 150 ppi (pixel per inch)
4. No bleed.
4. an RGB Black colour is not a CMYK BlacK colour. As a result, in pdf-file we had few black colour with different shades) at different places. Sometimes you cannot see the difference on your screen (on your display) - it depends on your monitor. But you will see this difference on a printed version of your mockup.
The cover is a face of a magazine. In order to get a cover of good quality with A4 page size I had to add a missing black area with exactly the same black colour. It wasn't enough. The PowerPoint program supports only rectangular-shape images. As you can see the main image has rounded corners. In fact it was a rectangular image with black areas at the corners. And that black colour differs from surrounded black colour.
Inside of the magazine we had pages with white background what doesn't make any problem to create missing bleed. Where it was possible I replaced low resolution images to good quality pictures.
This is one thing of hundreds of my prepress experience.