Influence of image resolution on image quality in telepathology

Image quality is a crucial factor in the diagnostic practice of telepathology. Because of technical and financial limitations there has to be made a compromise between high image quality and fast image transmission. There are no standardized thresholds defining minimal requirements in respect to the image quality during telepathological diagnostics with the purpose to guarantee diagnostic accuracy. Aim of this study is the investigation of the influence of the resolution of digital histological images on subjective perception. Observers were asked to compare a set of 50 image pairs projected by a slide projector. Each image pair consisted of a reference image of 1800 dpi resolution and a test image of lower resolution. Both were sampled out of an original photographic transparency. According to our results it would be recommendable to use the following resolutions in pixel per micrometer for the purpose of histopathological telediagnosis to meet the claims of viewers with high visual acuity: objective 1x: 0,19 pixel per µm; objective 4x: 0,43 pixel per µm; objective 10x: 1,09 pixel per µm; objective 20x: 2,17 pixel per µm; objective 40x: 4,35 pixel per µm.