<title>Low-frequency MTF estimation for digital imaging devices using slanted-edge analysis</title>

Abstract

Modulation transfer function (MTF) metrology and interpretation for digital image capture devices has usually concentrated on mid-to high-frequency information, relative to the half-sampling frequency. These regions typically quantify characteristics and operations such as sharpening, limiting resolution, and aliasing. However, a potential wealth of low-frequency, visually significant information is often masked in existing measurement results because of spatial data truncation. For print or document scanners, this influences measurements in the spatial frequency range of 0 to 2.0 cycles/mm, where the effects of veiling flare, micro flare, and integrating cavity effect (ICE) often manifest themselves. Using a form of edge-gradient analysis based on slanted edges, we present a method for measurement of these characteristics. By carefully adapting this well-established technique, these phenomena can be quantified. We also show how, in many cases, these effects can be treated as other spread-function or device-MTF components. The theory and field metrology of several devices using the adapted technique are also presented.

Temporal and Spatial Resolution Limit Study of Radiation Imaging Systems: Notions and Elements of Super Resolution

“…The candidate edge must also meet contrast and noise requirements for selection (Jain, 1989). This is because, the MTF value obtained with high contrast edge target is always larger than that obtained with lower contrast target for a given spatial frequency; therefore, when the MTF of a system is presented, the contrast of the line pair used to measure the MTF should be given (Williams, 2004). In our case the maximum contrast of the target image obtained is 37.68% calculated by Michelson formula (Michelson, 1927).…”

Resolution and light sensitivity tradeoff with pixel size

“…We measured the system MTF using the ISO standard ISO 12233 [6]. This method measures the system response to a slanted edge.…”

Applications of the phase transfer function of digital incoherent imaging systems

“…Yet another image-based method would be to utilize an edge target akin to the widely used slantededge measurement method [17][18][19]. While this method yields reliable MTF data, care should be exercised in extending this approach to PTF measurement, because the latter is highly sensitive to sampling phase.…”