ae TEE N 
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117 | 
PHOTOGRA PHIC INTERPRETABILITY 11 rom | 
liate |] 
tions are plotted in Figure 11 on an equal energy basis. These Ru 
functions are an imaged exponential, a gaussian, and a equivalent 4th teps 
degree gaussian, the 
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FOCAL POSITIONS - MICRONS RESOLUTION - LINES /MM and 
IDEALIZED SPREAD cns Am ore 
FIGURE II FIGURE I2 to 
The predicted contrast-resolution relationships for these three ho- 
spread functions are shown in Figure 12. These data show that high ess 
contrast resolution is not necessarily an advantage in the actual aerial his 
photographic operating area, since the lens which performed best at 
high contrast might actually be poorest at the low contrasts which 
exist in actual usage. The graphs of Figure 12 which are plotted on 
an equivalent energy basis, might also be plotted on the basis of equal 
resolution at maximum contrast. When this is done it becomes apparent tell 
that the fourth degree function is almost four times better than the ex- he 
ponential at a contrast of .05 and the gaussian is three times better. ial 
From the standpoint of performance appraisal and practical test- 
ing, spread function evaluation is difficult to handle. A method of 
greater practical interest seems to be available in the newly explored n- 
area of sine wave response or frequency response measurement. In In 
this method, bar test charts are used wherein the illumination amplitude les 
across the bars varies sinusoidally. Images of such charts at the focal he 
position of a lens are measured photoelectrically to determine the n- 
reduction in illumination amplitude as a function of bar spacing in the 
test chart, The illumination amplitude is equivalent to contrast and the lis 
bar spacing is referred to as the line frequency. ls 
Such data is illustrated in Figure 13. Curves A and B indicate 
the frequency-response curves for lenses. The response may be con- | 
sidered as related to image contrast. In particular, curves A and B may hc | 
be considered as corresponding to the A and B positions respectively t | 
in Figures 9 and 10. al | 
in | 
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9 S x: TT A fr eA YG CN ld ord — | 
Fr Are there questions pertaining to Mr acteristic of the particular emulsion. Does this | 
| Maruyasu’s presentation? answer your question? | 
Archives 6