COMPARISON OF SUBJECTIVE AND OBJECTIVE MEASUREMENTS WITH THE SINE-WAVE TESTING EQUIPMENT

• Document Type: CREST
• Collection: NGA Records (Formerly NIMA)
• Document Number (FOIA) /ESDN (CREST): CIA-RDP78B04747A002000030010-6
• Release Decision: RIFPUB
• Original Classification: K
• Document Page Count: 1
• Document Creation Date: December 28, 2016
• Document Release Date: January 22, 2001
• Sequence Number: 10
• Content Type: SUMMARY

Approved For Rose 2001/03/03 : CIA-RDP78B90 7AO02000030010-6
Comparison of subjective and objective measuremeazs with the Sine-Wave
Testing Equipment
Subjective: The eye is presented with resolution targets in a clear field,
within the eyepiece. The observer determines the highest
frequency he can see with a given target modulation which he
can vary. By making enough of these target modulation changes,
he can acquire enough data points to de transfer function.
This is accomplished by determining the ratio of his cut-off
modulation to the input target modulation.
The key here is the observer's cut-off modulation, and will
vary from observer to observer, with frequency. His judgements
are also affected by the level of illumination during his
observations. These two factors are strictly the observer's.,
and any transfer function determinations therefore include him
as part of the data.
Objective: To remove the observer from the me,#surements it is necessary
to hold the intensity of observation constant and to provide
a comparison object, in the eyepiece which holds cut-off
frequency of the eye constant, as well as the cutoff modulation.
This is accomplished by the sine-wave of low modulation. The
observer now adjusts frequency to match the sine-wave, varies
input (target) modulation until the sine-wave and target image
blend into a plain, flat density region and records his
input contrast. Now, everything about the observer is removed;
he is being used as a detector whose response is flat over all
frequencies of interest. Only the instru is being tested.
Declass Review by NIMA/DOD
Approved For Release 2001/03/03 : CIA-RDP78BO4747AO02000030010-6