METHOD AND APPARATUS FOR MAKING A COLOR STRIP MAP OF THERMAL VARIATIONS

• US 3,752,914 A
• Filed: 11/26/1971
• Issued: 08/14/1973
• Est. Priority Date: 11/26/1971
• Status: Expired due to Term

• Current Assignee: Dwight Allen Warner, George England
• Original Assignee: Dwight Allen Warner, George England
• Inventors: Warner, Dwight Allen, England, George
• Primary Examiner(s): Moffitt, James W.
• Application Number:
  US05/202,552
• Time in Patent Office: 627 Days
• Field of Search: 178/DIG.8,DIG.20,DIG.34,6.6R,6.7R,6.8
• US Class Current: 348/32
• CPC Class Codes: H04N 9/43 Conversion of monochrome picture signals to colour picture signals for colour picture display

Abstract

Thermal ground data and thermal reference data acquired by an airborne scanner are recorded on magnetic tape along with timing signals synchronized with the scanning. At some later time, the signals are played back and processed to produce a color image on a line-scanned cathode ray tube and the image is recorded on a continuous color film strip. Ground data signals are processed by a particular analog-to-digital converter to provide signals according to the instantaneous level of the thermal ground data compared to discrete reference levels which in turn are calibrated according to the thermal reference data. The digital signals gate color guns in the cathode ray tube at fixed intensity levels so that the color image is composed of a predetermined number of colors.

Claims

1. In the method of processing recorded electrical signals representing thermal variations in a scene to produce a color strip map thereof, said electrical signals being recorded on recording media with at least a first of said signals representing thermal variations in said scene acquired a line at a time along transverse scan lines and a second of said signals representing timing for said scan lines, the steps of extracting said first signal and said second signal from said recording media, processing said first signal to obtain a plurality of output signals each of which indicates when said first signal exceeds a respective predetermined reference level, selectively energizing a plurality of electron beam generating means in a line-scanned color display means at predetermined fixed intensity levels according to said output signals so that only a predetermined number of colors are displayed according to said predetermined reference levels while simultaneously causing a color display of said thermal variations in said ground scene to be generated a line at a time at said display means by initiating each line at said display means at substantially the same display position in accordance with said second signals so that each display scan line corresponds to a respective acquired scan line, said display scan lines being reoccurring horizontal scan lines at the same vertical position on said display means, and exposing a continuous strip of color film to said color display by moving said film strip past said display in a direction generally perpendicular to the direction of line scanning at said display to thereby produce a continuous strip map of said thermal variations in said scene.

2. The method set forth in claim 1 wherein said first signal is processed by continuously comparing said first signal to said reference levels to develop said output signals in digital form of predetermined fixed amplitude whereby said beam generating means are energized at fixed predetermined intensity levels according to said predetermined fixed amplitudes of said output signals.

3. The method set forth in claim 2 wherein said reference levels are selected to define a predetermined amplitude range having an upper amplitude limit, a lower amplitude limit and a predetermined number of amplitude subranges within said range, said upper limit reference level, said lower limit reference level and said subrange reference levels are compared against the instantaneous amplitude of said extracted data signal to develop said output signals in digital form so that a predetermined color in said display corresponds to said first signal being within a predetermined amplitude suurange and said display contains a predetermined number of basic colors as determined by said predetermined number of amplitude subranges.

4. The method of making a color strip map of thermal variations in a ground scene, said method being implemented by line-scanned color display means having a plurality of electron beam generating means therein adapted to be selectively energized to produce color variations at said display means, said method comprising flying an aircraft along a predetermined flight path over said ground scene while simultaneously acquiring thermal ground data from said ground scene taken a line at a time along scan lines generally transverse to said flight path, generating electrical data signals representing said thermal ground data, generating electrical timing signals having a predetermined timing relationship to acquisition of data along each of said ground scan lines, storing said data signals and said timing signals on recording media, subsequently extracting said data signals and said timing signals from said recording media, processing said extracted data signals to obtain a plurality of output signals each of which indicates when said extracted data signals exceed a respeCtive predetermined reference level, selectively energizing said beam generating means at predetermined fixed intensity levels according to said output signals so that only a predetermined number of colors are displayed according to said predetermined reference levels while simultaneously causing a color display of thermal variations in said ground scene to be generated a line at a time at said display means by initiating each line at said display means at substantially the same display position in accordance with said extracted timing signals such that each display scan line corresponds to a respective ground scan line, said display scan lines being reoccurring horizontal scan lines at the same vertical position on said display means, and exposing a continuous strip of color film to said color display by moving said film strip past said display in a direction generally perpendicular to the direction of line scanning at said display to thereby produce a continuous color strip map of thermal variations in said ground scene.

5. The method set forth in claim 4 wherein said data signals and said timing signals are recorded on magnetic tape on a real-time basis substantially coincidental with acquisition of said thermal ground data, and wherein said data signals and said timing signals are subsequently extracted from said magnetic tape.

6. The method set forth in claim 4 wherein 70mm color film is exposed from said display as said film is moved past said display in a direction generally transverse to scan lines on said display.

7. The method set forth in claim 4 wherein the steps of subsequently extracting and processing said signals, energizing said beam generating means while generating said color display and exposing said film are all performed at a ground location.

8. The method set forth in claim 7 wherein said extracted data signals are processed by continuously comparing said extracted data signals to said reference levels to develop said output signals in digital form of predetermined fixed amplitude whereby said beam generating means are energizd at fixed predetermined intensity levels according to said predetermined fixed amplitudes of said output signals.

9. The method set forth in claim 8 wherein said reference levels are selected to define a predetermined amplitude range having an upper amplitude limit, a lower amplitude limit and a predetermined number of amplitude subranges within said range, said upper limit reference level, said lower limit reference level and said subrange reference levels are compared against the instantaneous amplitude of said extracted data signal to develop said output signals in digital form so that a predetermined color in said display corresponds to said extracted data signal being within a predetermined amplitude subrange and said display contains a predetermined number of basic colors as determined by said predetermined number of amplitude subranges.

10. The method set forth in claim 9 wherein said amplitude range is divided into six subranges of substantially equal amplitude increments and said display is composed of six basic colors.

11. The method set forth in claim 10 wherein a first additional digital signal is generated when said amplitude of said extracted data signal is below said lower limit and a second additional digital signal is generated when said extracted data signal exceeds said upper limit, and wherein two additional colors are generated at said display in response to said first and second additional signals.

12. The method set forth in claim 11 wherein the color black is generated at said display in response to one of said additional digital signals and the color white is generated at said display in accordance with the other of said additional signals.

13. Apparatus for processing recorded electrical signals representing thermal variations in a scene to produce a color strip map thereof, said electrical signals being recorded on recording media with at least a first of said sigNals representing thermal variations in said scene acquired a line at a time along transverse scan lines and a second of said signals representing timing for said scan lines, comprising transducer means for extracting said first and second signals from said recording media, first reference source means providing a first amplitude reference, a second amplitude reference and a plurality of subrange amplitude references intermediate said first and second references, a plurality of level detection circuits each of which has a reference level input coupled to said reference source means to be responsive to a respective one of said first, second and subrange references, each of said detection circuits also being operatively coupled to said transducer means and responsive to its respective reference and said first signal to provide a respective digital output signal when said first signal exceeds a respective reference, line-scanned display means having a plurality of electron beam generating means for generating different colors on said display, circuit means coupled to said level detection circuits and to said beam generating means and responsive to predetermined selected combinations of said output signals to develop gating signals for energizing predetermined selected combinations of said beam generating means at predetermined fixed intensity levels to obtain a predetermined number of colors in said display, said line-scanned display means being responsive to said gating signals and said second signals to cause said display to be generated a line at a time with each display line beginning at substantially the same display position so that said display scan lines are reoccurring horizontal scan lines at the same vertical position, and means for exposing a continuous strip of color film to said color display by moving said film strip past said display in a direction generally perpendicular to the direction of line scanning at said display to thereby produce a continuous color strip map of said thermal variations in said scene.