Objective and Subjective Assessment of Image Recognition

Abstract

This paper describes two studies which used objective and subjective assessments to quantify the effect of target degradation on observers' recognition ability. ‘Noise’ inherent in a digital infra-red line scan system can result in a static line-to-line variation (pixel jitter) over the displayed imagery. The amount of target degradation is dependent upon both the amplitude and frequency of the pixel jitter. The results showed that, firstly, if an image is affected by pixel jitter, even with an amplitude of only 1 pixels, a significant interference in target recognition performance occurs. Secondly, the results from the subjective scaling mirrored closely the error data and therefore imply that this rating scale, may have widespread utility in target acquisition studies. Finally, the effect of pixel jitter appears to be robust. The effect was found not to be specific to a particular type of imagery and is, therefore, likely to generalise to other types of target and other imaging systems. The implication of these results for user-system specification is discussed.