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Light Range Extending Method

IP.com Disclosure Number: IPCOM000076743D
Original Publication Date: 1972-Apr-01
Included in the Prior Art Database: 2005-Feb-24
Document File: 2 page(s) / 42K

Publishing Venue

IBM

Related People

Hauke, FE: AUTHOR [+2]

Abstract

The range of light amplitude values recordable on photographic film is enhanced by forming a composite of separately exposed films. This is especially applicable in spatial filtering where the Fourier transform of a light pattern involves an unusually wide range of light values, which normally exceed the range of values recordable on standard film, as shown in Fig. 1. Step 1.

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Light Range Extending Method

The range of light amplitude values recordable on photographic film is enhanced by forming a composite of separately exposed films. This is especially applicable in spatial filtering where the Fourier transform of a light pattern involves an unusually wide range of light values, which normally exceed the range of values recordable on standard film, as shown in Fig. 1. Step 1.

The image is focused on emulsion "A" through a glass or plastic base "A" (an emulsion and a base together forming a photoplate) for a relatively short exposure, on the order of less than one second, depending upon the film type, object, and intensity of light source. This will record the high-intensity areas. Step
2.

Develop emulsion A, leaving it in a holder which allows exact replacement in setup. Step 3.

Cover the high-intensity area of emulsion A of photoplate A with an opaque masking fluid or substance. This step is not intrinsic to the procedure, but under certain conditions can improve the image. Step 4.

Expose emulsion "B" through photoplate A for a relatively long exposure, on the order of greater than one second. This records the low-intensity image areas, the high-intensity areas being blocked by emulsion A and the masking of Step 3. Step 5.

Remove one of the plates and develop emulsion B. Step 6.

Strip the masking from emulsion A. Step 7.

Replace the photoplate removed in Step 5, so that both plates are in coincidence to form a final composite through...