New methods are tried for measuring the distribution of practical resolution in human vision. Subjective tests are carried out that use degraded images with low-resolution areas outside a circular area with high-resolution. Subjective answers by subjects on their impression of the degraded images with high-resolution areas of various diameters are analyzed. As an objective test, eye mark tracks in a viewing field were recorded; the subjects were told to locate a target character in a projected character array on a screen in front of the subject. Each maximum viewing angle allowing recognition of characters of various sizes was obtained by measuring the radius defined as the last saccade distance just before finding the target character. The subjective test yields the result that subjects felt that image degradation was not annoying when they looked at a test image with 1/16 times degraded resolution outside a circle with visual angle of 7.2 degrees. A curve plotting the resolution distribution was obtained by objective tests; the curve shows has shape to the density distribution curve of cone cells on the retina.
Hideaki Takamiya, Makoto Omodani, Yasusuke Takahashi, "Resolution Distribution in the Human Vision" in Proc. IS&T Int'l Conf. on Digital Printing Technologies (NIP17), 2001, pp 780 - 783, https://doi.org/10.2352/ISSN.2169-4451.2001.17.1.art00077_2