Density discrimination can be accomplished through use of special photographic contouring material which has two sensitive layers (one negative, one positive) on single support. Process will be of interest to investigators who require finer discrimination of densities of original photograph for purposes such as identification of crops and analysis of energy levels of radiating objects

Godding, R. A.

English

NASA Technical Reports Server

February 1974	 B73-10441 
NASA TECH BRIEF 
Lyndon B. Johnson Space Center 
NASA Tech Briefs announce new technology derived from the U.S. space program. They are issued to encourage 
commercial application. Tech Briefs are available on a subscription basis from the National Technical Information 
Service, Springfield, Virginia 22151. Requests for individual copies or questions relating to the Tech Brief program may 
be directed to the Technology Utilization Office, NASA, Code KT, Washington, D.C. 20546. 
Improved Discrimination in Photographic Density Contouring 
The problem: 
Important scientific information can be extracted 
from aerial photography by I isolating or identifying 
those areas of a photograph which have equal densities. 
These densities may represent areas of the same re-
flectivity, such as a single crop, or areas of equal 
energy, such as equal temperatures of a hot glowing 
object. Standard techniques of density discrimination 
are either too complicated or too expensive for use by 
the average investigator. The technique previously used 
at the Johnson Space Center did not provide the fine 
discrimination that was required in some cases. 
The solution: 
Density i discrimination can be accomplished through 
the use of a special photographic contouring material 
(Agfacontour Professional film or an equivalent) which 
has two sensitive layers (one negative, one positive) on a 
single support. One layer has the normal characteristic 
of a negative film - an increase in exposure causes 
(after processing) an increase in density of opacity. The 
other layer reacts just the reverse - an increase in 
exposure results in a decrease in density. The relative 
sensitivity of the two layers is such that at a particular 
intermediate exposure level, both layers have low 
density. 
When a print is made onto the contour film from a 
black-and-white photograph, all those areas of the 
original photograph having a particular narrow range of 
densities will be reproduced as clear on the print. Those 
areas of the original which were darker I or lighter than 
that specific density range will be reproduced as black. 
The specific band of densities thus isolated can be 
changed by varying the intensity of the printing light or
the time of exposure. However, the range of this band 
of isolated densities (0.30) is not adequate for some 
requirements. Therefore, a technique for reducing the 
range of isolated densities has been developed. 
How it's done: 
Using the same contour film reduplicated 'in a high 
contrast mode, the range of isolated densities can be 
decreased to less than 0.08. Specifically, the contour 
film which has been exposed through a deep yellow 
filter (such as CC150Y) is printed onto a high contrast 
photographic film. I The first generation print is then 
reprinted onto the same high contrast material to make 
a duplicate. This i results in an overall reproduction 
gamma of approximately 22.0. The limit to which this 
reduction can be carried is a function of the statistical 
variation of the densities of the original contour 
material or the original photographic subject. Caution 
should be exercised in processing the photographic 
materials, and in maintaining Iaccuracy in the exposure 
determination\for the original contour film. 
Notes: 
1. This process will be of interest to investigators who 
require a finer discrimination of the densities of an 
original photograph for purposes such as identification 
of crops and analysis of energy levels of a radiating 
object. 
2. Requests for further information may be directed to: 
Technology Utilization Officer 
Johnson Space Center 
Code AT3 
Houston, Texas 77058 
Reference: T5P73-10441 
(continued overleaf) 
This document was prepared under the sponsorship of the National
	
Government assumes any liability resulting from the use of the 
Aeronautics and Space Administration. Neither the United States 	 information contained in this document, or warrants that such use 
Government nor any person acting on behalf of the United States 	 will be free from privately owned rights.
.
https://ntrs.nasa.gov/search.jsp?R=19730000441 2020-03-17T07:29:46+00:00Z
Patent status: 
Inquiries concerning rights for the commercial use of 
this invention should be addressed to: 
Patent Counsel 
Johnson Space Center 
Code AM 
Houston, Texas 77058 
Source: R. A. Goodding of
Technicolor Graphic Services, Inc. 
under contract to

Johnson Space Center 
(MSC-12588)
. 
B73-10441	 I	 Category 03


Improved discrimination in photographic density contouring

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