Visual illusions, their causes, characteristics and applications (1922)
Luckiesh, Matthew, b. 1883 · New York, D. Van Nostrand company · leaf 132
IRRADIATION AND BRIGHTNESS - CONTRAST 117 appears much brighter than the one (same gray) amid the white environment. This can be demon- strated easily to an audience by means of a figure two feet long. It is interesting to carry the experiment further and place a F of much darker gray on the black… … Fig. 63. — Illustrating brightness-contrast. is actually a much darker gray than the other. To become convinced that the two grays are of the same brightness in Fig. 63, it is only necessary to punch two holes in a white or gray card at such a distance apart that they will lie respectively over…
Optical illusions
Internet Archive · Cornell University Library · Public domain (published before 1931). Free to use for anything.
