Method and system in video image reproduction

• US 5,115,229 A
• Filed: 06/26/1990
• Issued: 05/19/1992
• Est. Priority Date: 11/23/1988
• Status: Expired due to Fees

• Current Assignee: Hanoch Shalit
• Original Assignee: Hanoch Shalit
• Inventors: Shalit, Hanoch
• Primary Examiner(s): Weldon, Ulysses
• Application Number:
  US07/544,232
• Time in Patent Office: 693 Days
• Field of Search: 358/10, 358/69, 358/139, 358/107, 358/903, 358/76, 324/404, 340/716, 340/717, 340/793
• US Class Current: 345/2.2
• CPC Class Codes: H04N 1/4078 using gradational references, e.g. grey-scale test pattern analysis
• CPC Class Codes: H04N 1/6055 using test pattern analysis

Abstract

A system and method for the accurate reproduction of the tone and luminance of a first video monitor screen includes, in one embodiment, a first video monitor and a second video monitor, each with a CRT screen. A gray scale test pattern is shown on both screens. The test pattern on each screen is measured using a spot photometer and the results are entered into a computer memory look-up table and compared, a tone-by-tone basis. A set of corrections is obtained for each tone of the gray scale. Those compensating corrections are used to adjust the luminance, on a pixel-by-pixel basis, of the second video screen of the second video monitor, so that the second screen is compensated to produce a gray scale which reproduces the tone and luminance values of the gray scale on the first screen.

Claims

1. The method reproducing a series of images on a second video screen of a second video monitor which are accurate tone reproductions of the luminance ratios of the video images on a first video screen of a first video monitor including the steps of:

(a) forming a gray scale test video image on the first and second video screens;

wherein said second video monitor includes electronic means to vary the luminance values on said second screen on a pixel-by-pixel basis, said test images having predetermined tone scales including defined areas differing in luminance ratios;

(b) luminance measuring the differences in luminance in the gray scale on the first screen to obtain a first set of luminance difference values using a photoelectric photometer and entering the first set of luminance difference values into a computer having computer memory and storing said first set in the computer memory;

(c) luminance measuring the differences in luminance in the gray scale on the second screen to obtain a second set of luminance difference values using a photoelectric photometer and entering the second set of luminance difference values into the computer;

(d) in the computer, comparing said entered second set of luminance values with said first set of luminance values stored in computer memory;

(e) using the computer to generate a set of corrections for each luminance value for each pixel of said second screen, and

(f) altering the tones on the second video screen according to said set of computer produced corrections by altering the settings of the electronic means of said second video device.

6. The method as in claims 1, 2 or 3 wherein said second screen is a LCD (liquid crystal display).

7. The method as in claims 1, 2 or 3 wherein said second screen is the screen of a CRT (cathode ray tube).

8. The method as in claims 1, 2, 3, or 4 wherein the photometer output produces electrical signals and including the step of automatically entering said photometer signals into said computer by connecting said electrical signal output to said computer.

9. The method of claims 1 or 2 wherein said luminance sensing of said second screen and entering into the computer of the second set of sensed luminance values is done on a daily basis, during days the second video monitor is used.

10. The method of claim 1 wherein first and second sets are derived from different tone panels of the test image.

2. The method of reproducing a series of images on a second video screen of a second video monitor which are of accurately reproduced luminance values of the video images on a first video screen of a first video monitor including the steps of:

(a) forming a gray scale test video image on the first video screen and the second video screen, wherein the second video monitor includes electronic means to vary the luminance values on said second screen on a pixel-by-pixel basis, the test images having predetermined tone scales including defined areas differing in luminance and wherein said first and second video monitors each have screen brightness and contrast controls;

(b) adjusting the brightness and contrast controls of said second video monitor so that the highest and the lowest luminance values on the second video screen are the same as the highest and lowest luminance values of the first video screen;

(c) luminance sensing the luminance values in the gray scale on the first and second screens using a photoelectric photometer and entering the sensed luminance values into a computer;

(d) comparing said entered luminance values from said second screen with a set of numerical correction values stored in computer memory representing the luminance values of the measured first video screen;

(e) calculating in the computer a set of corrections for each luminance value for each pixel of said second screen, and altering the luminance values on the second video screen according to said set of computer produced corrections by altering the settings of the electronic means of said second video device.

3. The method of reproducing a series of images on a second video screen of a second video monitor which are accurate tone reproductions of the luminance ratios of the video images on a first video screen of a first video monitor including the steps of:

(a) forming a color test video image on he first and second video screens having differences in the values of hue, chroma and brightness;

wherein said second video monitor includes electronic means to vary the hue, chroma and brightness values on said second screen on a pixel-by-pixel basis;

(b) measuring the differences in hue, chroma and brightness in the test image on the first screen to obtain a first set of color values using a color photoelectric photometer and entering the first set of color values into a computer having computer memory and storing said first set in the computer memory;

(c) measuring the differences in hue, chroma and brightness in the test image on the second screen to obtain a second set of color values using a color photoelectric photometer and entering the second set of color values into the computer;

(d) in the computer, comparing said entered second set of color values with said first set of color values stored in computer memory;

(e) using the computer to generate a set of corrections for each color value for each pixel of said second screen, and

(f) altering the colors on the second video screen according to said set of computer produced corrections by altering the settings of the electronic means of said second video device.

4. The method of reproducing a series of images on a video screen of a video monitor which are accurate tone reproductions of the luminance ratios of the images of an object including the steps of:

(a) forming a gray scale test pattern at the object and a gray scale test video image on said video screen;

wherein said video monitor includes electronic means to vary the luminance values on said screen on a pixel-by-pixel basis, said test image and test pattern each having predetermined tone scales including defined areas differing in luminance ratios;

(b) measuring the differences in density in the gray scale on the test pattern to obtain a first set of values using a photoelectric densitometer and entering the first set of values into a computer having computer memory and storing said first set in the computer memory;

(c) luminance measuring the differences in luminance in the gray scale on the screen to obtain a set of luminance difference values using a photoelectric photometer and entering the set of luminance difference values into the computer;

(d) in the computer, comparing said entered second set of luminance values with said first set of values stored in computer memory;

(e) using the computer to generate a set of corrections for each luminance value for each pixel of said screen, and

(f) altering the tones on the video screen according to said set of computer produced corrections by altering the settings of the electronic means of said video device.

5. The method of reproducing a series of images on a video screen of a video monitor which are accurate color reproductions of the hue, chroma and brightness of an object, including the steps of:

(a) forming a color test video image on the video screen and a color test pattern at the object;

wherein said video monitor includes electronic means to vary the hue, chroma and brightness values on said screen on a pixel-by-pixel basis, said test image and test pattern having predetermined defined areas differing in hue, chroma and brightness;

(b) measuring the differences in hue, chroma and brightness in the test pattern to obtain a first set of color values using a photoelectric color photometer and entering the first set of color values into a computer having computer memory and storing said first set in the computer memory;

(c) measuring the differences in hue, chroma and brightness in the test image on the screen to obtain a second set of color values using a photoelectric photometer and entering the second set of color values into the computer;

(d) in the computer, comparing said entered second set of color values with said first set of color values stored in computer memory;

(e) using the computer to generate a set of corrections for each color value for each pixel of said screen, and

(f) altering the colors on the video screen according to said set of computer produced corrections by altering the settings of the electronic means of said video device.

11. A system for producing a series of images on a second video screen of a second video monitor which are accurate tone reproductions of the luminance ratios of the video images on a first video screen of a first video monitor including;

(a) first and second video monitors having first and second video screens, respectively, said second video monitor including electronic means to vary the luminance values on said second screen on a pixel-by-pixel basis.

(b) means for forming a gray scale test video image on the first and second video screens;

said test images having predetermined tone scales including defined areas differing in luminance ratios;

(c) photoelectric photometer means for measuring the luminance values in the gray scale on the first and second screens to obtain first and second sets of luminance values, a computer having a computer memory and computer interface means connected to said photometer means for entering the measured luminance values of said first set into computer memory and entering the second set into the computer;

(d) comparison means within said computer for comparing said entered second set of luminance values with said first set of values stored in computer memory;

(e) correction computer means within said computer to produce a set of corrections for each luminance value for each pixel of said second video screen based upon said comparison; and

(f) video tone altering means for altering the tones on the second video screen according to said set of computer produced corrections.

12. A system for producing a series of images on a second video screen of a second video monitor which are accurate color reproductions of the hue, chroma and brightness of the video images on a first video screen of a first video monitor including;

(a) first and second video monitors having first and second video screens, respectively, said second video monitor including electronic means to vary the color values on said second screen on a pixel-by-pixel basis.

(b) means for forming a color test video image on the first and second video screens;

said test images having predetermined defined areas differing in hue, chroma and brightness;

(c) photoelectric color photometer means for measuring the values hue, chroma and brightness on the first and second screens to obtain first and second sets of color values, a computer having computer memory and computer interface means connected to said photometer means for entering the measured color values of said first set into computer memory and entering the second set into the computer;

(d) comparison means within said computer for comparing said entered second set of color values with said first set color values stored in computer memory;

(e) correction computer means within said computer to produce a set of corrections for each color value for each pixel of said second video screen based upon said comparison; and

(f) video tone altering means for altering the tones on the second video screen according to said set of computer produced corrections.