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Pages Two (2) 

To: R. Buchanan 

Subject: Optical Evaluation Procedures Date: October 10, 1967 

1. Attachment #1 is the generalized Test Plan which will be used for the evaluation of the MDS ATS optics breadboard. Besides allowing for qualitative 

and quantitative visual inspection (i. e. , tribar targets), it will generate 

sufficient optical performance data (i. e. , point spread functions, contrast 

transmittance, etc. ) to allow the Visibility Laboratory to produce realistic 

image photographs. This will enable the following to be done: 

Allow for comparisons to be made of similarly produced images using 

the predicted ATS AVE optical characteristics, thereby assuring a 

more complete understanding of image simulation requirements. 

Determine whether the proposed substitution of an "AVE like" ATS 

eyepiece into the MDS at a later date will actually produce a more 

appropriate image. If not, suggested modifications to its design can 

be made sufficiently early. 

Assess the posSibility of using the MDS design fdr the MMSE. 

d. Develop confidence in the GE/ITEK capability to develop proper optics 

for simulator use. 

e. Develop tests procedures for use in acceptance testing of the AVE ATS 

optics. 

2. Attachment #2 gives more complete details of how we plan to use the quantitative optical performance data at the Visibility Laboratory. For this 

present effort, we will rely upon photographs produced using the predicted 

characteristics of the AVE ATS as a diffraction limited system (perfect 

optics) and the MDS actual optical performance photographic images in a 

comparative manner. Appropriate objects have already been selected, 

i. e. , fighter on runup pad, various types of trucks in a parking lot, helicopters and a variety of aircraft on a ramp. J. Harris has already incorporated these images in his computer programs along with scale size to 

produce 127 X magnification, contrast degradation appropriate to presently 

conceived atmospheric models, etc. When the MDS Bench Data are 

therefore available, J. Harris, in a very short order will be able to produce 

the appropriate photographs to be used in our evaluations. 

3. Page 3 and 4 of Attachment #2 detail work that we hope to accomplish in 

a. 

b. 

c. 
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the future. This will give further information as to the visual performance 

capacity to detect and hopefully rapidly assess objects as seen in the HP.A 

task. Ranges of size and form complexity can therefore be developed to 

help further identify the general categories to be used as activity indicators. 

V 

F. Doppelt 

L. Thomas 

2 Atchs: 

(1) Ltr, Aug 31, 1967, WHS-434, Subj: Generalized Test Plan 

for Evaluation of the Breadboard for the IvIDS 

(Composed of Optical Elements and Mirrors), 4 Pages 

Memo, 13 Sep 1967, Subj: Simulation and Analysis of 

Imagery for Visual Optical Instruments, 4 Pages, 

UNCLASSIFIED 

Cys to: 

Bernstein 

F. Doppelt 

C. Gandy 

L. Thomas 

D. Truly 

( 2) 
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Pages:Four (4) 

To: R. A. Marott 

Subject: Generalized Test Plan for Evaluation of the Date: August 31, 1967 

ATS Breadboard for the MDS 

(Composed of Optical Elements and Mirrors) 

The test program is to be divided into two general inspection categories. The 

first to be a qualitative inspection, the purpose of which is to obtain a general 

feeling for the quality of the device and to assist in defining some of the specific parameters to be measured in the second category. This second category 

is a quantitative inspection and will additionally serve to generate data which 

can be input to computer programs whose function is to determine the fitness 

of the system. All tests should be run at 150-200 ft. Lamberts equivalent at 

eyepiece- exit pupil. 

The qualitative inspection will be done by observing at the simulator reticle 

plane the images of various objects. This inspection will be done without 

an eyepiece but using a traveling microscope of suitable power, with and 

without the presence of the anamorphic lens system. The objects to be 

used are: 

1. Bar target resolution chart' 

a. low about (2.0:1) contrast - standard Itek supplied chart of 

known to contra ,ct. 

2. Point/source (artificial_stir) generated by Itek. 

3. Color bar targets (TBD re: Discussion between Gehrke and 

Shannon). 

Images of these objects will be viewed on axis and off-axis (in many azimuths 

sufficient to delineate the points where maximum image change occurs) at 

various settings throughout the zoom range (with and without the flip lens) 

and at various representative settings of the anamorphic lenses-(0°, 30°, 

60° and 90° angles between the anamorphic axes). Red, green and blue 

narrow band filters will be used as well as white light illumination. The 
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The purpose of this examination will be to observe: 

1. General quality 

2. Apparent resolving power 

3.. Visual contrast rendition 

4. Field curvature 

5. Degree of correction of off-axis aberrations (coma, astigmatism, 

etc.) 

6. Chromatic aberrations 

7. Visual effect of system spectral transmission 

In addition, appropriate scene material, supplied by Itch at 2:1, 10:1 and 

30:1 contrast levels at 100 line pairs, will be viewed as a further check on 

overall quality. This material will be viewed with a typical eyepiece instead 

of the microscope and should be of proper scale. The effect of anamorphic 

and other distortions will be observed as well as the general appearance of 

the image. 

The quantitative inspection will be made at the reticle plane for all tests 

and through an eyepiece for. resolution tests as well. The quantitative tests 

will consist of: 

1. Bar chart resolution 

a. low contrast (same as used for qualitative tests) 

b. high contrast (MIL-STD 150A). This test will be to determine 

compliance with resolution specs. These tests are to be made 

on axis and at off-axis points as established in the qualitative . 

inspection and at various zoom and anamorphic settings. 

2. System transmission 

a. The percentage transmission of the system to a uniformly 

-illuminated source will be measured. 

b. The contrast transmittance for small objects will be measured. 

This will be measured by scanning the image of a relatively 

small opaque object with a- microphotometer which will have 

photometric precision of 10% or better. If NBis the background brightness, N* is the minimum brightness of the image 

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of the opaque object and T is the system transmittance, the 

contrast transmittance is defined as: 

Go 1 + N* 1 

NB T 

3 Point spread measurements of images of artifical stars. These 

measurements will be made.on axis and at selected off-axis points 

at various zoom and anamorphic lens settings (as determined by 

qualitative tests). They will be measured using "white" light as 

well as through red,. green and blue filters (as time allows). The 

measurements will be made with either or both the Itek scanning 

microphotometer or a microphotometer capable of measuring 

the point spread function in the sagittal and tangential planes. 

The scanning aperture of either photometer will be a pinhole 

whose diameter is 1/10 of the diameter of the image of the point 

source where the intensity of the image is 1/10 of the maximum 

• intensity. 

1.0 

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pinhole diam < To 

From the test data described above, the following comparisons, image 

. effects and performance predictions can be accomplished: 

1. Compare the optical characteristics of the breadboard with those 

predicted for the ATS AVE. 

2. Through computerized correlation techniques, the quadratic content of scenes of known quality as affected by the characteristics 

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of the measured system can be determined and the "image egradation" demonstrated. 

3. By utilizing the information developed in 2. and a psycho-physical 

data bank maintained by the Visibility Laboratory, the probabilities 

of accomplishing certain binary visual-perceptual tasks (presenceabsence, same-different) can be computed. 

F. F. Doppelt 

L. L. Thomas 
SANTA BARBARA • SANTA CRUZ 

F ts 1.4 NW. 

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UNIVERSITY OF CALIFORNIA, SAN DIEGO 

BERKELEY • DAVIS • IRVINE • LOS ANGELES • RIVERSIDE • SAN DIEGO • SAN FRANCISCO 

VISIBILITY LABORATORY SAN DIEGO, GALIF011111A 92152 

SCRIPPS INSTITUTION OF OCEANOCRAPIIY 

13 September 1967 

MEMORANDUM 

TO: Dr. S. Q. Duntley 

SUBJECT: Simulation and Analysis of Imagery 

for Visual Optical Instruments 

The purpose of this memorandum is to describe the 

study of computer simulation of optical imagery for visual use on 

telescopic and microscopic systems. 

Background and General Description 

At various stages in the design and development of an 

optical system for visual use, information with respect to the system 

.resolution is evolved, first in the form of design calculations, and 

later in the form of optical bench test data on components of the system. This information may be in the form of point spread functions 

or optical transfer functions. While it is true that information in this 

form does.properly define the system resolution, it is an extremely 

difficult and sometimes nearly impossible task to picture on the basis 

of these data how the images of real objects of interest will appear. 

Every optical system is designed and built with some specific data acquisition tasks in mind, and it is important to know at the earliest possible moment, how the performance of these tasks will be affected by 

the system resolution. 

In the present study, high resolution photographs of selected objects of interest will be cnvolved with point spread function 

data to produce pictures which represent predictions of the imagery 

which will result from the completed optical instrument. By viewing 

these images and attempting to perform typical recognition and identification functions, it is believed that a more nearly correct judgement 

can be made as to the adequacy of the system resolution than can be 

made from numerical definitions of resolution or from viewing either 

point spread function of optical transfer function data. 
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Digitizing of Photographic Images 

After selection of high resolution images of objects of 

interest, positive transparancies of these images will be made with 

scanning and digitizing of these films accomplished by means of our • 

image processing film scanning equipments. The positive transparancies will be made at an enlargement such that the maximum object dimension on the film will be slightly less than 6.4 mm in order , 

that digitizing can be performed on a 64 x 64 element matrix with 100 

micron distance between elements.' Each image so scanned will produce a deck of IBM cards. Digitized pictures will be made at the time 

of scan by means of the cathode-ray-tube display system in order that 

the resolution limitations associated with the scanning operations can 

be seen clearly. A proper criterion should be that, when viewed at the 

correct angular subtense, the discrete nature of the digitized images is 

not apparent. 

Convolution Operations 

The convolution operations will be accomplished with 

Fourier transform operations using existing computer programs. The 

first step in the procedure will be to Fourier transform the point spread 

function data to derive the two-dimensional complex, i. e. amplitude 

and phase, optical transfer function.- The next step will be to Fourier 

transform the digitized images previously described. Complex multiplication of the two spectra will be performed to yield the degraded image 

spectrum. An inverse transform of this degraded spectrum will yield 

the degraded image. These operations will be performed on the UCSD 

CDC 3600. 

Generation of Pictures of the Degraded Images 

For each degraded image the computer will produce a deck 

of cards defining the image on a 64 x 64 matrix of points with 100 linear 

gray scale steps, i. e. , each point in the degraded image will have an 

integer value between 0 and 99. These "picture decks" will serve as input to our image processing picture generation equipment in which the 

data is used to modulate a cathode-ray-tube display. which is photographed 

by means of a Polaroid oscilloscope camera. Type PN film will be used 

in order that a photographic negative is obtained. 

Positive transparancies will be made from these negatives 

and arrangements made for viewing of these films at the proper angular 

subtense. Positive transparancies will also be made from the original 

undegraded images so that a direct comparison of the effect of the degradation can be made. 

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Theoretical Back-Ups 

It is probable that the viewing of the computer generated 

degraded images will be sufficient to answer questions as to the adequacy of the resolution of the optical system. There are a number of 

quantatative analysis techniques which can be applied to the problem 

if their application seems necessary. These techniques allow calculation of the probability of correctly performing specific binary decision 

tasks. For example, if we have a degraded image and we know a'priori, 

that the image is due to either object A or object B, then there are several mathematical formulations which allow us to be quantitative about 

the ability to decide correctly between the object alternatives based on 

the image information. 

The first of these involves the concept of the summative 

function of the human visual system. It has been demonstrated that, for 

the purpose of determining visual detection thresholds, the visual system 

can be approximated by a linear spatial filter. This spatial filter is called 

the summative function. If the sum/native function is convolved with the 

object to be detected, detection will occur if the peak value of this convolution exceeds a threshold value which can be determined from existing basic 

vision data. An extension of this concept to the case of binary decisions has 

been made with limited but successful experimental verification. In the case 

of the binary decision it is first necessary to overlay the degraded images 

which would result from object A and object B with a position and orientation 

which maximizes the cross-correlation between the two images. A point-bypoint difference is then taken and this "difference image" convolved with the 

summative function with the criterion that if the difference image is visually 

detectable, the binary decision can be properly made. 

A second formulation of the binary decision process also involves 

the difference image as defined above. In this second formulation, however, 

the difference image is operated upon by the optical transfer function for the 

optical system of the human visual system in order to determine the retinal 

image which would be produced by the difference image. This retinal image 

is squared at each point and spatially integrated to determine the "quadratic 

content." This numerical value, coupled with retinal noise level, inferred 

from basic psychophysical data, allows statements to be made as to the probability of correctly making the required binary decision. 

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Psychophysical Back-Uas 

Pairs of degraded pictures involving some typical binary 

decision can be generated by the techniques previously described and, 

used as the basis of a forced choice vision experiment in which probability of correct decision is experimentally determined as a function 

of a variable such as a scale factor on the point spread function. This 

is probably not required for most applications because as the point 

spread function is scaled in size, the transition from certain identification to no identification is quite rapid and the subjective judgements 

described earlier can usually bracket the transition range rather well. 

James L. Harris, Sr. 

Associate Director 

JLH:pw 

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