Method and apparatus for improving time variant image details on a raster display

• US 5,929,842 A
• Filed: 07/31/1996
• Issued: 07/27/1999
• Est. Priority Date: 07/31/1996
• Status: Expired due to Fees

• Current Assignee: Fluke Corporation (Fortive Corp.)
• Original Assignee: Fluke Corporation (Fortive Corp.)
• Inventors: Rey, William, Vertregt, Maarten
• Primary Examiner(s): Powell, Mark R.
• Assistant Examiner(s): SAID, MANSOUR M
• Application Number:
  US08/692,833
• Time in Patent Office: 1,091 Days
• Field of Search: 345/147, 345/88, 345/87, 345/77, 345/63, 345/53, 345/35, 345/20, 345/13, 345/23, 345/134, 345/132, 345/89
• US Class Current: 345/690
• CPC Class Codes: G01R 13/02 for displaying measured electric variables in digital form
• CPC Class Codes: G01R 13/342 for displaying periodic H.F. signals G01R13/345 takes precedence
• CPC Class Codes: G01R 13/403 using passive display devices, e.g. liquid crystal display or Kerr effect display devices
• CPC Class Codes: G09G 1/162 for displaying digital inputs as analog magnitudes, e.g. curves, bar graphs, coordinate axes, singly or in combination with alpha-numeric characters cathode-ray oscilloscopes for displaying analog inputs, singly or in combination with alpha-numeric characters G01R13/20; television receiver circuitry for displaying supplementary, e.g. alpha-numeric, information H04N5/445

Abstract

A method of displaying digital samples with enhanced image details on a raster display using a limited set of brightness values is provided. Digital samples are interpolated and stored as pixel information in high resolution intensity memory. An adaptive mapping process maps the high resolution intensity information to low intensity brightness information in a manner so as to maximize image details. An equal number of brightness levels from light to dark are allocated in each column along the sweep. An adaptive recombination process combines past and present brightness information in a manner that best preserves image details when the temporal behavior of the display image is changing. A raster display device is employed to display the image which is stored in the display memory as pixels arranged by row and column.

Claims

1. In a raster display device, an apparatus for improving display image details, comprising:

(a) an intensity memory having a row and column arrangement for receiving and storing intensity information over a plurality of sweeps; and

(b) an adaptive mapping process coupled to said intensity memory for converting said intensity information into present brightness levels from a set of brightness levels having less resolution than said intensity information wherein said adaptive mapping process produces predetermined portions of each of said brightness levels from said set of brightness levels within each of said columns.

2. An apparatus for improving display image details according to claim 1 further comprising:

(a) a display memory for storing said present brightness values according to said row and column arrangement; and

(b) a raster display having a matrix of pixels according to said row and column arrangement coupled to said display memory for receiving said present brightness values and displaying said display image.

3. An apparatus for improving display image details according to claim 2 further comprising an adaptive recombination process interposed between said adaptive process and said display memory for receiving said present brightness values from said adaptive mapping process and past brightness values from said display memory wherein said adaptive recombination process combines said past and present brightness values according to a composite indicator responsive to said past brightness values to produce new brightness values to be stored in said display memory.

4. An apparatus for improving display image details according to claim 3 wherein said composite indicator comprises a series of control states.

5. An apparatus for improving display image details according to claim 4 wherein said adaptive recombination process combines said past brightness values and said present brightness values according to a selected truth table from a set of truth tables responsive to said series of control states.

6. An apparatus for improving display image details according to claim 5 wherein said set of truth tables comprises OR, SUM, DECREMENT PAST, and INTERMEDIATE.

7. An apparatus for improving display image details according to claim 3 wherein said adaptive recombination process combines said past and present brightness values in a proportional manner according to said composite indicator.

8. An apparatus for improving display image details according to claim 1 wherein said intensity information is interpolated from digital samples.

9. An apparatus for improving display image details according to claim 2 wherein said adaptive mapping process maps equal numbers of each of said brightness levels from said set of brightness levels within each of said columns.

10. An apparatus for improving display image details according to claim 1 wherein said adaptive mapping process maps said intensity information to said set of brightness levels according to a set of quantiles.

11. An apparatus for improving display image details according to claim 1 wherein said intensity memory stores each of said intensity values with a resolution of 4,096 levels.

12. An apparatus for improving display image details according to claim 2 wherein said display memory stores each of said brightness levels with a resolution of four levels.

13. A raster display device for displaying a display image with improved details, comprising:

(a) an intensity memory having a row and column arrangement for receiving and storing intensity information over each sweep;

(b) an adaptive mapping process coupled to said intensity memory for receiving and converting said intensity information into present brightness levels from a set of brightness levels wherein said set of brightness levels has less resolution than said intensity information and said adaptive mapping process produces predetermined portions of each of said brightness levels from said set of brightness levels within each of said columns;

(c) a display memory for storing said present brightness values according to said row and column arrangement; and

(d) a raster display having a matrix of pixels according to said row and column arrangement coupled to said display memory for receiving said brightness values and displaying said display image developed over at least one of said sweeps.

14. A raster display device according to claim 13 further comprising an adaptive recombination process interposed between said adaptive process and said display memory for receiving said present brightness values from said adaptive mapping process and past brightness values from said display memory wherein said adaptive recombination process combines said past and present brightness values according to a composite indicator responsive to said past brightness values to produce new brightness values to be stored in said display memory.

15. A raster display device according to claim 14 wherein said composite indicator comprises a series of control states.

16. A raster display device according to claim 15 wherein said adaptive recombination process combines said past brightness values and said present brightness values according to a selected truth table from a set of truth tables responsive to said series of control states.

17. A raster display device according to claim 16 wherein said set of truth tables comprises OR, SUM, DECREMENT PAST, and INTERMEDIATE.

18. A raster display device according to claim 14 wherein said adaptive recombination process combines said past and present brightness values in a proportional manner responsive to said composite indicator.

19. A raster display device according to claim 13 wherein said intensity information is interpolated from digital samples.

20. A raster display device according to claim 13 wherein said adaptive mapping process maps equal numbers of each of said brightness levels from said set of brightness levels within each of said columns.

21. A raster display device according to claim 13 wherein said adaptive mapping process maps said intensity information to said set of brightness levels according to a set of quantiles.

22. A raster display device according to claim 13 wherein said intensity memory stores each of said intensity values with a resolution of 4,096 levels.

23. A raster display device according to claim 13 wherein said display memory stores each of said brightness levels with a resolution of four levels.

24. In a raster display device, a method for displaying a display image with improved details, comprising:

(a) storing intensity information in a row and column arrangement in an intensity memory during each of a plurality of sweeps; and

(b) adaptively converting said intensity information into present brightness values, said present brightness levels having lower resolution than said intensity information, wherein predetermined portions of each of said brightness levels from said set of brightness levels are produced within each of said columns.

25. A method for displaying a display image with improved details according to claim 24 further comprising:

(a) storing said present brightness values in a display memory according to said row and column arrangement; and

(b) displaying said display image on a raster display having a matrix of pixels corresponding to said row and column arrangement responsive to said present brightness values received from said display memory.

26. A method for displaying a display image with improved details according to claim 24 further comprising adaptively recombining said brightness values with past brightness values from said display memory according to a composite indicator responsive to said past brightness values to produce new brightness values to be stored in said display memory.

27. A method for displaying a display image with improved details according to claim 26 further comprising generating a series of control states according to said composite indicator.

28. A method for displaying a display image with improved details according to claim 27 further comprising combining said past and present brightness values according to a selected truth table from a set of truth tables responsive to said series of control states.

29. A method for displaying a display image with improved details according to claim 28 wherein said set of truth tables comprises OR, SUM, DECREMENT PAST, and INTERMEDIATE.

30. A method for displaying a display image with improved details according to claim 26 further comprising adaptively recombining said past and present brightness values in a proportional manner responsive to said composite indicator.

31. A method for displaying a display image with improved details according to claim 24 further comprising interpolating said intensity information from digital samples.

32. A method for displaying a display image with improved details according to claim 24 wherein said predetermined portions of each of said brightness levels within each of said columns are equal.

33. A method for displaying a display image with improved details according to claim 24 further comprising adaptively mapping said intensity information to said set of brightness levels according to a set of quantiles.