RIP SETTINGS
Any objects that have a fill or stroke of 100% black will be automatically overprinted when the file is sent to the RIP (where the press plates are made). You will need to keep this in mind especially when placing black objects over images etc as the image will more than likely have a greater ink mix than 100% black and therefore appear darker (showing through the black object, see examples below).
To compensate for this we recommend you do either of the following:

OPTION A:
Set your black object to 99% black, this will then not be overprinted when it is processed by the RIP and being 99% it will fill in to become solid when printed.

OPTION B:
You can change your black object to include 40-60% Cyan this will intensify the black object helping to cover the difference between the pic and object.

OPTION C:
You could simply crop the image to suit, and either make the black object just large enough to cover the pic or
you could put a .3pt black stroke set to overprint on the black object to give you the trapping needed (see Trapping and Overprinting Tutorials).

OPTION D:
If the image that the black object is covering has a particularly high ink load (contains high percentages of Cyan, Magenta, Yellow and Black) then it may be better to make your object a similar intensity, this however is a last resort not your first option as any white text or objects place over such a rich black may not register well.

Rich black example: If the pic has large areas containing a high colour mix e.g. 77% Cyan, 60% Magenta, 40% Yellow and 76% Black, then you may need to change your top object from 100% black, 0% Cyan, 0% Yellow, 0% Magenta to 60% Cyan, 40% Magenta, 5% Yellow, 100% Black. Remember this is a last resort if you have white or light coloured text above the black object. It is always preferable to use option A, B or C for best results.

RELATED TOPICS:
See also the Overprinting and Trapping Tutorials

Example of what you will see on your screen with a 100% BLACK object covering a picture


Example of how this same example will appear when printed


Disclaimer: Print Domain offers this advice free of responsibility. It is the sole responsibility of the client to provide files to our specification, any error in provided files and resulting printing is the responsibility of the client.