Observer-sensitivity to edge and line blur was examined by measuring just-noticeable differences of blur as a function of contrast, edge-profile shape, line width, and for white lines on black and black lines on white. At high luminance ratios, observers can discriminate a blurred image from an unblurred image when the edge-transition width (10–90% luminance points) is of the order of 25 sec of arc. However, when both images are blurred, they can be discriminated when they differ by as little as 5–10 sec of are.
© 1981 Optical Society of America
James R. Hamerly and Charles A. Dvorak, "Detection and discrimination of blur in edges and lines," J. Opt. Soc. Am. 71, 448-452 (1981)