The resolution of a digital camera is defined as its ability to reproduce fine detail in an image. To test this ability methods like the Slanted Edge SFR measurement developed by Burns and Williams 1 and standardized in ISO 12233 2 are used. Since this method is -in terms of resolution measurements -only applicable to unsharpened and uncompressed data an additional method described in this paper had to be developed. This method is based on a Sinusoidal Siemens Star which is evaluated on a radius by radius or frequency by frequency basis. For the evaluation a freely available runtime program developed in MATLAB is used which creates the MTF of a camera system as the contrast over the frequency.
To measure the spectral response of digital cameras is usually a time-consuming and expensive task. One method to gain the spectral response data is the use of reflectance charts and estimation algorithms. To improve the quality of the measurement narrow-band light is necessary. Usually an expensive and complicated monochromator is used to generate the narrow-band light.This paper proposes the use of a set of narrow-band interference filters as an alternative to a monochromator. It describes the measurement setup and data processing. A detailed quality assessment of the measurement data shows, that the quality is comparable to a measurement with a monochromator. The interference filter equipment is more affordable, easier to use and faster. The characterization of one device takes less than 10 minutes. The pros and cons compared to other methods are also discussed.The setup consists of a set of 39 narrow-band interference filters, which are photographed one after another. A modified slide projector is used for illumination. Software was developed to read the camera's response to the filter and process the data.
The quality of digital cameras has undergone a magnificent development during the last 10 years. So have the methods to evaluate the quality of these cameras. At the time the first consumer digital cameras were released in 1996, the first ISO standards on test procedures were already on their way. At that time the quality was mainly evaluated using a visual analysis of images taken of test charts as well as natural scenes. The ISO standards lead the way to a couple of more objective and reproducible methods to measure characteristics such as dynamic ranges, speed, resolution and noise. This paper presents an overview of the camera characteristics, the existing evaluation methods and their development during the last years. It summarizes the basic requirements for reliable test methods, and answers the question of whether it is possible to test cameras without taking pictures of natural scenes under specific lighting conditions. In addition to the evaluation methods, this paper mentions the problems of digital cameras in the past concerning power consumption, shutter lag, etc. It also states existing deficits which need to be solved in the future such as optimized exposure and gamma control, increasing sensitivity without increasing noise, and the further reduction of shutter lag etc.
The edge-based Spatial Frequency Response (e-SFR) method is well established and has been included in the ISO 12233 standard since the first version in 2000. A new 4 th edition of the standard is proceeding, with additions and changes that are intended to broaden its application and improve reliability. We report on results for advanced edge-fitting which, although reported before, was not previously included in the standard. The application of the e-SFR method to a range of edge-feature angles is enhanced by the inclusion of an angle-based correction, and use of a new test chart.We present examples of the testing completed for a wider range of edge test features than previously addressed by ISO 12233, for nearzero-and -45-degree orientations. Various smoothing windows were compared, including the Hamming and Tukey forms. We also describe a correction for image non-uniformity, and the computing of an image sharpness measure (acutance) that will be included in the updated standard.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.