Digital cameras span a large range in price and performance. Consumers often
focus mainly on the resolution in pixels when shopping for a camera. Of
equal importance is the quality of the optics and the exposure response. Digital
cameras generally have a linear exposure response, but the amount of
noise and the dynamic range vary. It is difficult to obtain quantitative information
on these parameters to make an informed assessment. This work explores
and demonstrates first-principles methods to measure the exposure
response to make meaningful comparisons between different camera models.
It also shows how to make the most of a particular camera by measuring its
noise level and dynamic range, to understand the limits of its useable ISO
amplification. The methods only require a computer and free software to
download images and extract their RGB pixel values. The analysis, based on
the RGB values, uses standard spreadsheet software. The procedures are
therefore accessible to anyone with a digital camera and computer, and will
help to reduce speculation in comparing cameras, and help consumers make
an informed decision.
Johnson, Z. (2009) GetRGB software developed by The Beckman Institute Imaging Technology Group at the University of Illinois at Urbana-Champaign.