Recognition of Black and White Photographic Image

• Published in: The Journal of The Society of Scientific Photography of Japan Vol. 26; no. 3; pp. 127 - 134
• Main Authors: FUJIMURA, Ikuo, HIRATA, Akifumi
• Format: Journal Article
• Language: Japanese
• Published: THE SOCIETY OF PHOTOGRAPHY AND IMAGING OF JAPAN 1963
• ISSN: 1884-6327
• DOI: 10.11454/photogrst1934.26.3_127

Experiments were performed to determine the recognition of three kinds of 16mm. black and white negative-films. At first, circle-square target was used, and only the contrast of the image was varied using an image of comparatively large size. Also, the negative image was purposely made vague by properly making it out-of-focus to make the sharpness of the optical system and the film negligible. When the recognition index of Barrow was measured by varying the negative density, developing time, and the gradation of the positive material, (1) the recognition index reached its maximum at a comparatively low negative density and with comparatively weak development, and (2) the effect of the gradation of the positive material was little, as Barrow reported. All these results are well explained by the change of graininess. The graininess is an important factor that affects the recognition. In the second experiment, the size-contrast recognition was measured under the conditions of actual photographic procedures. The recognizable size of a square target was about 0.05-0.09mm. square, when the contrast was sufficiently high. When a camera lens, having a focal length several times that of a naked eye, is used-the size of the image on a film is several times that of the image size on the retina-it is almost equal to the recognition of a normal eye.