Print sharpness evaluation using image analysis and a new peak area algorithm

Abstract

The sharpness of a printed image, whether it has been printed within the graphic arts industry or it is a photographic image, can be described as the rate of transition from the printed area to the non-printed area. Ultimately, this will dictate the clarity and the quality of the printed image. A new method to measure the sharpness of the edge of a printed image, called the peak area method, has been developed. This technique offers increased accuracy and reliability in a wide range of applications when compared to existing techniques. The peak area method, which uses the gradient of the grey-level profile of an image, is described in detail. This technique is compared with several existing methods on a number of replicated images of varying sharpness, before it is used to measure the sharpness of printed samples obtained from a number of different printing processes. Unlike some previously used print sharpness measurement methods, the peak area method is capable of measuring the print sharpness of any print where there is a transition from a printed to a non-printed area, thus enabling a wider range of images to be measured and quantified.

Keywords:

• print sharpness
• image analysis
• algorithm
• printing