For many years, the widening use of digital imaging products, e.g., digital cameras, has given rise to much attention in
the market of consumer electronics. However, it is important to measure and enhance the imaging performance of the
digital ones, compared to that of conventional cameras (with photographic films). For example, the effect of diffraction
arising from the miniaturization of the optical modules tends to decrease the image resolution. As a figure of merit,
modulation transfer function (MTF) has been broadly employed to estimate the image quality. Therefore, the objective of
this paper is to design and implement an accurate and cost-effective MTF measurement system for the digital camera.
Once the MTF of the sensor array is provided, that of the optical module can be then obtained. In this approach, a spatial
light modulator (SLM) is employed to modulate the spatial frequency of light emitted from the light-source. The
modulated light going through the camera under test is consecutively detected by the sensors. The corresponding images
formed from the camera are acquired by a computer and then, they are processed by an algorithm for computing the
MTF. Finally, through the investigation on the measurement accuracy from various methods, such as from bar-target and
spread-function methods, it appears that our approach gives quite satisfactory results.