For a wide range of application areas, quantifying the ability of a spectral image to satisfy the informational requirements of an application task would be desirable. We propose that this metric may be termed the "image utility" and present a method for assessing the utility of spectral images for the subpixel target detection task. In this paper, we investigate the sensitivity of this utility metric to various image chain parameters. In particular, we examine the effect of small variations of preprocessing and target detection scenario parameters on the assessed utility of a spectral image. We offer a method of quantifying the sensitivity to facilitate a rank ordering of parameter sensitivities. This exploration constitutes an initial step towards gaining a fuller understanding of the key parameters that drive spectral image utility.