the proper camouflaging pattern is added the resulting photographic negative or print can be used to produce printed documents the alternating dot pattern could also be produced by a photoplotter although this latter method is more expensive it is much more accurate one reason for the increased accuracy is that it is not produced in a single series of film rather it is produced on a single piece of film one dot at a time the resulting screen pattern may be stored on magnetic tape and reproduced as required however regardless of the method used to produce the alternating dot pattern the result is the same increased copy proof protection and a more versatile aesthetically pleasing document the copier protection of existing systems breaks down at the darker copier settings because the higher frequency background becomes visible to the copier the cancellation phrase does not darken as quickly as the background and so the background diminishes the contrast of the copy proof feature the present alternating dot system on the other hand contains both the low frequency dots that copy over the entire copier range and the higher frequency dots which copy at the darker copier settings therefore as the copier 39 s resolution increases and the background becomes darker the cancellation phrase also darkens the application of copy proof documents has been limited by the inability of the previous technique to reproduce patterns that.