Over the past century a number of factors have been observed to improve the quality of sampled images. Three of these phenomena are reviewed. The reasons for improvement based on perception studies are given, the improvements are quantified, and how they can be used in a practical television system is shown. Interlaced scanning reduces vertical resolution for several reasons involving spatial and temporal masking effects in visual perception. A progressive scan avoids these limitations. Because of the oblique effect in vision and the statistical orientation of lines in scenes, diagonal sampling reduces the required number of pixels in an image. Quantitatively, our measurements show that the number of pixels is reduced by a factor of 1.4 for the same perceived sharpness. In addition, by taking advantage of the octave-wide tuning bands in visual perception, our measurements show that the perceived resolution in the vertical direction for a progressive scan can be double that of an interlaced scan. Using diagonal sampling, a 1920×1080 image with progressive scan at 60 frames/s requires the same transmission bit rate as a 1920×1080 Cartesian sampled image scanned interlaced at 30 frames/s. This results in an image that appears to be much sharper than the 1080 line interlaced format without the interlace artifacts.
William E. Glenn,
"Visual perception studies to improve the perceived sharpness of television images," Journal of Electronic Imaging 13(3), (1 July 2004). https://doi.org/10.1117/1.1762887