Video display device and color temperature correction method for the same

• US 20030020736A1
• Filed: 03/07/2002
• Published: 01/30/2003
• Est. Priority Date: 07/27/2001
• Status: Active Grant

• Current Assignee: Maxell, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Matono, Takaaki, Sakai, Takeshi, Takata, Haruki, Kimura, Katsunobu, Kato, Wataru
• Granted Patent: US 7,084,880 B2
• Time in Patent Office: Days
• US Class Current: 345/690
• CPC Class Codes: G09G 2320/0666 for control of colour parameters, e.g. colour temperature
• CPC Class Codes: G09G 5/02 characterised by the way in which colour is displayed details of colour display specific for CRTs G09G1/28; specific for flat matrix panels other than liquid crystal displays G09G3/2003; specific for liquid crystal displays G09G3/3607
• 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

A video display device that allows the color temperature of the signals in white color attributes having high luminance and low chroma saturation to be corrected with high precision is provided together with the color temperature correction method for the same so as to visually obtain a desirable white color on display.

The signal processing circuit for the color temperature correction according to this invention comprises an A/D converter to convert the video signals as input into digitalized signals, a matrix circuit to convert the digitalized signals as output from said A/D converter into luminance signals and at least two color difference signals, a hue conversion circuit to obtain hue signals from the color difference signals as output from said matrix circuit, a hue correction circuit to correct said hue signals, a chroma saturation conversion circuit to obtain chroma saturation signals from said color difference signals, a chroma saturation correction circuit to correct said chroma saturation signals and a color temperature correction circuit to perform the color temperature correction on the respective hue and chroma saturation signals as corrected.

Claims

1. A video display device wherein said device is provided with a means to correct a color temperature of video signals in white color attributes having a given luminance or more and a given chroma saturation or less among said video signals as input.

2. A video display device comprising a signal processing circuit provided with a color temperature correction circuit to perform a color temperature correction on video signals as input and a display device, to which device the video signals as subjected to the color temperature correction by said color temperature correction circuit are supplied for display, wherein said color temperature correction circuit is provided with a means to correct the color temperature of the video signals in white color attributes having a given luminance or more and a given chroma saturation or less among said video signals as input.

3. A video display device according to claim 2, wherein said signal processing circuit comprises an A/D converter to convert said video signals as input into digitalized signals, a matrix circuit to convert the digitalized signals as output from said A/D converter into luminance signals as well as at least two color difference signals, a hue processing circuit to obtain hue signals from the color difference signals as output from said matrix circuit, a chroma saturation processing circuit to obtain chroma saturation signals from said color difference signals and a control circuit, wherein based on set values of a given luminance level and a given chroma saturation level as supplied from said control circuit said color temperature correction circuit performs an operation to correct the color temperature of the signals in said white attributes into a higher level thereof among the hue signals as output from said hue processing circuit and the chroma saturation signals as output from said chroma saturation processing circuit.

4. A video display device according to claim 3, wherein said color temperature correction circuit comprises a first color temperature correction section to perform the color temperature correction on the signals in said white color attributes among the hue signals as output from said hue processing circuit, a second color temperature correction section to perform the color temperature correction on the signals in said white color attributes among the chroma saturation signals as output from said chroma saturation processing circuit, a first selection circuit to select and output either the signals as output from said first color temperature correction section or the hue signals as output from said hue processing circuit and a second selection circuit to select and output either the signals as output from said second color temperature correction section or the chroma saturation signals as output from said chroma saturation processing circuit.

5. A video display device according to claim 4, wherein said signal processing circuit further comprises a detection circuit to detect an area of the signals in said white color attributes having a given luminance or more and a given chroma saturation or less among said video signals as input, wherein said detection circuit upon the detection of said area outputs a control signal to said first and second selection circuits for selecting the signals to be output from said first and second color temperature correction sections.

6. A video display device according to claim 5, wherein said control circuit supplies said set values of a given luminance level and a given chroma saturation level to said detection circuit as a basis for detecting said area.

7. A video display device according to claim 6, wherein said detection circuit comprises a means to further detect the signals having a hue of a given range within the area of the signals in said white color attributes.

8. A video display device according to claim 4, wherein said signal processing circuit further comprises a color difference signal conversion circuit to convert the signals as output from the first and second selection circuits into the color difference signals and an inverse matrix conversion circuit to convert the color difference signals as output from said color difference signal conversion circuit and the luminance signals as output from said matrix circuit into R, G and B signals, which signals are supplied to said display device.

9. A video display device according to claim 3, wherein said hue processing circuit comprises a hue conversion circuit to convert the color difference signals as output from said matrix circuit into the hue signals and a hue correction circuit to correct the signals having a given range of hue among the hue signals as output from said hue conversion circuit so as to output the signals as corrected to said color temperature correction circuit, wherein said chroma saturation processing circuit comprises a chroma saturation conversion circuit to convert the color difference signals as output from said matrix circuit into the chroma saturation signals and a chroma saturation correction circuit to correct the signals having a given range of chroma saturation among the chroma saturation signals as output from said chroma saturation conversion circuit so as to output the signals as corrected to said color temperature correction circuit, wherein said control circuit sets the range and a degree of hue to be corrected by said hue correction circuit and the range and a degree of chroma saturation to be corrected by said chroma saturation circuit.

10. A video display device according to claim 4, wherein said signal processing circuit further comprises a luminance correction circuit to correct the luminance signals as output from said matrix circuit.

11. A video display device according to claim 10, wherein said luminance correction circuit comprises a black expanding circuit to control an amplitude of the signals in black color having a given black luminance or less, a white expanding circuit to control the amplitude of the signals in white color having a given white luminance or more, a contrast control circuit to control the amplitude of the signals as output from said white expanding circuit and a brightness control circuit to control a direct current level of the signals as output from said contrast control circuit.

12. A video display device according to claim 11, wherein said control circuit, based on maximum and minimum levels of the luminance signals as output from said matrix circuit, determines respective set values of a given black luminance and a given white luminance so as to supply said set values to said black and white expanding circuits while supplying the respective set values of a degree of amplitude control of the signals to said black expanding circuit, said white expanding circuit and said contrast control circuit as well as the set value of the direct current control level of the signals to said brightness control circuit.

13. A video display device in any one of claims 3, 6, 9 or 12, wherein said control circuit is a microcomputer.

14. A video display device comprising a signal processing circuit provided with a color temperature correction circuit to perform a color temperature correction on video signals as input and a display device, to which device the video signals as subjected to the color temperature correction by said color temperature correction circuit are supplied for display, wherein said signal processing circuit is provided with a conversion means to convert said video signals into digitalized hue and chroma saturation signals, wherein said color temperature correction circuit, which circuit performs the color temperature correction on the respective hue and chroma saturation signals as converted, is provided with a correction means to increase the color temperature of the signals in white color attributes having a given luminance or more and a given chroma saturation or less among said hue and chroma saturation signals.

15. A video display device according to claim 14, wherein said correction means is provided with a means to make a hue of the signals in said white color attributes closer to the hue of blue color and a means to enhance the chroma saturation of the signals in said white color attributes.

16. Color temperature correction method to perform the color temperature correction on video signals as input, wherein the color temperature correction is performed on the signals in white color attributes having a given range of luminance and chroma saturation.

17. Color temperature correction method to perform the color temperature correction on video signals as input, wherein an operation is performed to correct the color temperature of respective hue and chroma saturation components of the signals in white color attributes having a given luminance or more and a given chroma saturation or less among said signals as input.

18. Color temperature correction method according to claim 17, wherein the color temperature correction for the signals in said white color attributes is independently performed from that for the video signals other than those in said white color attributes.

19. Color temperature correction method to perform the color temperature correction on video signals as input comprising the steps of converting said video signals into digitalized signals, separating said digitalized signals into luminance signals and color difference signals, separating said color difference signals into hue signals and chroma saturation signals and performing the color temperature correction to increase the color temperature of the signals in white color attributes having a given luminance and a given chroma saturation among said hue and chroma saturation signals.

20. Color temperature correction method according to claim 19, wherein said color temperature correction comprises the steps of making a hue of the signals in said white color attributes closer to the hue of blue color and enhancing the chroma saturation of the signals in said white color attributes.