Print quality for air photo interpretation

Abstract

Summary: An experiment is described in which military photo interpreters select between stereographs on the basis of information content. The 16 stereographs used were all printed from the same pair of negatives of scale 1:8,400. Each stereograph was printed differently to emphasize one or more of 13 targets in the scene. The interpreters viewed individual targets in each stereograph through an Abrams CF-8 stereoscope and recorded their choice on a questionnaire. A choice was also made for overall appearance without using the stereoscope. The results from 35 observations are: Comparison Preference Preference Percent (Averaged from N targets) Light Transparency Light Transparency 100 vs. Light Transparency Dark Transparency

Light Print Light Print 93 vs. Dark Print

Transparency Transparency 81 vs. Print

Higher Gradient Higher Gradient 80 vs. Lower Gradient (Within similar density ranges) - - - - - - - - - - - - - - - - - - - - - - *USAF Institute of 1echnology with duty station at Boston University Institute of Aerial Photography. This thesis work was supported under Contract AF 33(166)-21.

Collimated Light Collimated Light 74 Printing vs. Diffuse Light Printing

Eastman Variable Eastman Variable 66 Contrast Contrast vs. DuPont Varigam

Unferrotyped Unferrotyped Glossy 59 Glossy Surface Surface vs. Ferrotyped Glossy Surface

It is concluded that for gaining intormation under the conditions of this study military photo interpreters show: 1. Strong preference for positive transparencies instead of positive paper prints. 2. Strong preference tor positives which were printed from collimated light instead of positives printed from diffuse light. 3. Strong preference for lighter appearing instead or darker appearing positives; providing the details are neither "washed out" nor '"blocked up." There is a tendeney for very light "washed out highlights" to be accepted while "'blocked up shadows" are rejected. 4. Strong preference for positive material D-Log E Curve gradients which are higher instead of lower for the same general range of densities in the positive. 5. Moderate preference for prints made on Eastman Variable Contrast Paper (Experimental Emulsion 47763A) inetead of prints made on DuPont Varigam when both are printed with ultraviolet light for use in the toe region or their respective D-Log E curves. This does not mean that DuPont Varigam paper is unacceptable. The Eastman paper has the advantage of reaching the same Dmax for all contrasts, and of having the same directional color response as Varigam. 6. Only a slight preference for unglossed surface prints instead of glossy surface prints. The conclusions would seem to warrant expenditure of time and effort toward: 1. Development of suitable equipment for viewing positive transparencies in stereo without cutting individual frames fromm the roll. 2. Study the feasibility of using: a. Variable contrast positive transparency in roll form. b. Only variable contrast paper for continuous tone printing (instead of papers of separate contrasts). 3. Supplying a summary of the information in this report regarding the photo interpreter's preferences in Technical Order form to appropriate photofinishing agencies.