Perceptual image quality in digital dermoscopy

When using a conventional analogue dermatoscope, imperfect focus or other image quality problems are readily detected and corrected by the dermatologist. In digital dermoscopy, however, images may be inspected by the dermatologist well after their acquisition. In such a situation, there is no possibility to remedy image quality deficiencies. This demonstrates the importance of image quality in digital dermoscopy. In this paper, we investigate the effects of resolution, blur, and color consistency on the perceived quality of digital dermoscopic images. The effects are quantified using task-based adaptive measurements of human observers perceived threshold for each imaging parameter. Our results indicate that the thresholds for imaging parameters depend on the image content and the observer and that the acceptable quality threshold lies well below what is achievable with our current imaging equipment. An unexpected and interesting observation we made in the course of experiments is that a user may prefer a less colorful image to enhance visualization of certain details.