Edge-raggedness evaluation using slanted-edge analysis

The standard ISO 12233 method for the measurement of spatial frequency response (SFR) for digital still cameras and scanners is based on the analysis of slanted-edge image features. The procedure, which applies a form edge-gradient analysis to an estimated edge spread function, requires the automated finding of an edge feature in a digital test image. A frequently considered (e.g., ISO 13660 and 19751) attribute of printed text and graphics is edge raggedness. There are various metrics aimed at the evaluation of the discontinuous imaging of nominally continuous features, but they generally rely on an estimation of the spatial deviation of edge or line boundaries, the tangential edge profile (TEP). In this paper, we describe how slanted-edge analysis can be adapted to the routine evaluation of line and edge quality. After locating and analyzing the edge feature, the TEP is estimated. The estimation of RMS deviation and edge spectrum are described.