Color correction system and method with scene-change detection

• US 4,694,329 A
• Filed: 04/12/1985
• Issued: 09/15/1987
• Est. Priority Date: 04/09/1984
• Status: Expired due to Term

• Current Assignee: Cintel SRL
• Original Assignee: Corporate Communications Consultants, Inc. (Aduddell Industries, Inc.)
• Inventors: Chayka, Stanley J., Belmares-Sarabia, Armand
• Primary Examiner(s): Shepperd, John W.
• Application Number:
  US06/722,801
• Time in Patent Office: 886 Days
• Field of Search: 358/22, 358/29, 358/105, 358/183
• US Class Current: 348/586
• CPC Class Codes: H04N 19/142 Detection of scene cut or scene change
• CPC Class Codes: H04N 19/179 the unit being a scene or a shot
• CPC Class Codes: H04N 19/87 involving scene cut or scene change detection in combination with video compression
• CPC Class Codes: H04N 5/147 Scene change detection
• CPC Class Codes: H04N 9/73 Colour balance circuits, e.g. white balance circuits or colour temperature control camera processing pipelines for colour balance H04N23/88

Abstract

In a scene-by-scene color corrector, automatic color correction circuitry produces color correction signals which are stored and utilized in preparing color-corrected video tape. Preferably, the automatic correction circuit tests only a pre-selected portion of the video picture displayed on a monitor. This portion or "window" is visible on the monitor screen, and its position and size can be changed as desired. The use of the "window" permits the exclusion of portions of the picture on which the automatic circuitry is less than fully effective, or which do not have components desirable for use in automatic color correction. If a separately variable luminance signal is produced, the automatic color correction circuitry preferably uses the luminance signal as a reference, thus allowing one to maintain color balance despite changes in the luminance signal. A scene-change analyzer determines whether the average window signal level in at least a portion of one field is different from the average window signal level in at least a portion of another field by a predetermined amount, and if so, it provides a suitable output signal. A scene-change analyzer may be used in a color corrector for scene-by-scene corrections. The film or tape transport may be stopped after a scene-change signal is produced, and the color correction values may be adjusted while the film or tape is stopped. Alternatively, the transport may continue to move the film or tape after a scene-change signal is produced, and the color correction values may be adjusted while the film or tape is moving.

Claims

1. A color correction system for color correcting video picture signals representative of images stored by an image recording medium, comprising:

means for moving the image recording medium and producing video picture signals representative of each of the images stored by the image recording medium;

display means responsive to said video picture signals for displaying pictures corresponding to each of the images stored by the image recording medium;

scene analysis means for analyzing at least one of the video picture signals in each of a plurality of pictures to detect a scene change, said scene analysis means automatically producing a scene-change signal in response to a scene change, said scene analysis means including means for determining a first average level of a video signal corresponding to a color component of the video picture signals in a portion of a first field, means for determining a second average level of said video signal in said portion of a second field, means for evaluating the difference between the first and second average levels based upon a predetermined standard, and means for automatically producing said scene-change signal if the predetermined standard is satisfied, said scene analysis means further including means for selectively changing the size and position of said portion of the first and second fields;

color correction means for selectively producing color correction signals for said video picture signals;

first storage means for selectively storing said color correction signals in response to a first manual command;

position signal means for producing position signals indicative of the position of each of the images stored by the image recording medium;

means for determining the location of an initial image of a new scene from the scene-change signal and from the position signals, said location determining means producing a location signal representative of the location of the initial image of the new scene;

second storage means for selectively storing said signal representative of the location of the initial image of the new scene in response to a second manual command;

readout means for reading from said first and second storage means said color correction signals and said location signals, respectively; and

combining means for selectively combining color correction signals read from said first storage means with said video picture signals, said combining means being responsive to the location signals read from said second storage means and to the position signals from said position signal means.

2. A color correction system as in claim 1, wherein said first storage means and said second storage means store color correction signals and a location signal, respectively, in response to the same manual command.

3. A color correction system as in claim 1, wherein said transport means stops moving the image recording medium after a scene-change signal is produced by said scene analysis means.

4. A color correction system as in claim 1, wherein said color correction means includes means for automatically producing said color correction signals in response to a third manual command.

5. A method for color correcting video picture signals representative of images stored by an image recording medium, comprising the steps of:

moving the image recording medium;

producing video picture signals representative of each of the images stored by the image recording medium;

displaying pictures corresponding to each of the images stored by the image recording medium;

analyzing at least one of the video picture signals in each of a plurality of pictures to detect a scene change, said analyzing step including the steps of determining a first average level of a video signal corresponding to a color component of the video picture signals in a portion of a first field, determining a second average level of said video signal in said portion of a second field, evaluating the difference between the first and second average levels based upon the predetermined standard, said analyzing step further including the step of selectively changing the size and position of said portion of the first and second fields;

automatically producing a scene-change signal if the predetermined standard is satisfied;

selectively producing color correction signals for at least one of said video picture signals;

selectively storing said color correction signals in response to a first manual command;

producing position signals indicative of the position of each of the images stored by the image recording medium;

determining the location of an initial image of a new scene from said scene-change signal and from said position signals;

producing a location signal representative of the location of the initial image of the new scene;

selectively storing said location signal in response to a second manual command;

reading said color correction signals and said location signals; and

selectively combining said color correction signals with said video picture signals in response to said location signals and said position signals.

6. A method as in claim 5, wherein the storing steps are accomplished in response to the same manual command.

7. A method as in claim 5, further comprising the step of stopping the image recording medium after a scene-change signal is produced.

8. A method as in claim 5, wherein the step of selectively producing color correction signals includes automatically producing said color correction signals in response to a third manual command.