SUBJECTIVE SHARPNESS OF IMAGES 



573 



4. Horizontal and Vertical Resolutions 



The effect of unequal horizontal and vertical resolutions upon sharp- 

 ness is shown in Fig. 5. The various rectangular figures of confusion, 

 which were intercompared in a manner which will be described pres- 



115,000 



2 



<o 



WIDTH TO HEIGHT RATIO OF FIGURE OF CONFUSION 



Fig. 5 — Sharpness of small-sized motion pictures as a function of the relative 

 values of horizontal and vertical resolutions. The conventional field of view is a 

 rectangle whose height is 1/4 the viewing distance and whose width is 4/3 the height. 

 Each point represents 150 observations at a viewing distance of 30 inches. 



ently, are shown along the axis of abscissae, positioned according to the 

 logarithm of the ratio of width to height, for the sake of symmetry. 

 Three curves are shown, each for a different constant value of the area 

 of the figure of confusion, which determines the sharpness for the 

 central square shape (as in Fig. 1). At the right the relative areas are 

 illustrated and specified in terms of the number of figures of confusion 

 in the conventional field of view, whose width is 4/3 of its height and 

 which is viewed at 4 times its height. 



Sharpness, the subjective variable, is plotted along the axis of 

 ordinates in liminal units. This unit denotes a difference in sharpness 



