APPLICATION OF COLOR TO IMAGE ENHANCEMENT

• Document Type: CREST
• Collection: NGA Records (Formerly NIMA)
• Document Number (FOIA) /ESDN (CREST): CIA-RDP78B04747A000100070035-6
• Release Decision: RIPPUB
• Original Classification: K
• Document Page Count: 4
• Document Creation Date: December 28, 2016
• Document Release Date: July 21, 2000
• Sequence Number: 35
• Content Type: REPORT

Declass Review, NIMA/DoD
Approved For Release 01/07/30: CIA-RDP78B04747A0001070035-6
25X1A
In the process of image enhancement, we seek to detect information
which is recorded on a photograph, and, by suitable transformations, re-
present this information as a modified image in such a manner that the in-
formation is more perceptible to the human observer. The
Image Enhancement Instrument accomplishes this by a number of techniques,
such as area scan filtering, frequency filtering, contrast enhancement, auto-
matic contrast control, and line drawing representations. The instrument
functions to produce a black and white image from a black and white input
photographic transparancy.
The criterion in enhancement is the production of a new image which
better displays the information on the original photograph; this objective is
not always synonymous with the faithful reproduction of the original scene
which was photographed. Thus, a deliberate distortion (In the intensity
sense, rather than the geometric shape sense ), of the overall transfer char-
acteristic between original scene and the ultimate display, is introduced in
order to accomplish enhancement.
One very intriguing method of output display involves the use of color
for presenting the enhanced image. This may be accomplished even though
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Application to Color to Image Enhancement---continued
no color information is present at the input, i.e. the input photograph is black
and white. The colors used in the output display do not necessarily represent
the colors contained in the original scene; they are introduced in a synthetic
Y
manner, for the purpose of rendering more perceptible the original information.
In this sense, the process seeks to exploit the color perceptiveness of the
observer as a better means for "coupling" the Information source ( the original
photograph) to the output device ( the human observer).
25X1A Figure 1 shows a means for achieving this objective. At the left, portions
of the Image Enhancement Instrument are shown; an input trans-
parency is converted to a number of different electrical signals. These are com-
bined in the Color Transformation Electronics Units into three corrmponent signals,
which create, through the modulated lights source and scanner-camera-processor
chain, three images, all black and white, but differing one from the other, which
are projected simultaneously by the tri-color projector.
The criteria for the generation of the R, G, and B signals in the color
transformation electronics, as well as the settings of the individual intensities
of the three colors in the display projector, can be established by a program of
study and experimentation. One possible transformation process is depicted in
Figures II and III. In Figure II is shown a locus of colors, starting at A (blue)
and proceeding along the arrows through a complete range of colors, ending at
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Application of Color to Image Enhancement----continued
point W (white). The output display colors may be caused to progress along
this locus in accordance with the amplitude of the picture signal from any one
of the five outputs from the image enhancement electronics, thus displaying the
image in a complete range of colors, as opposed to shades of gray. The realizable
colors within the line of spectral colors on the I .C .I. diagram may be traversed
in any locus desired. The one shown is created by the transfer characteristic shown
in Figure III, which shows individual outputs of the R. B, and G signals required
to traverse the locus shown in Figure II. (Points are designated to correspond
between the two figures) . For example, point D is composed of half red and half
greeen; it is therefore yellow in color. Point W, which is created for the bright-
est spots on the input image, is an equal mixture of the three colors, and is there-
fore white in appearance.
A locus may be traversed in response to signals other than input amp4ltude.
For example, the outputs of the three channels of the enhancement instrument
might be applied individually to the three channels, R, G, and B . In this manner,
the fine detail on the picture will modulate the red, the medium detail green, and
the coarse detail the blue color components in the output display.
The effect on the output display of these processes can best be established
by a program of experimentation with actual images. It should be possible to
achieve criteria forthe design of a color enhancement "nsturment which, through
exploitation of the color sensitivity of the human eye, greatly improves the r erception
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Approved For Release 2001/07/30 : CIA-RDP78BO4747A000100070035-6