JP2010128483A - Image processing apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image processing apparatus capable of displaying a moving image with high quality according to the kind of a display panel and an operation environment. <P>SOLUTION: A brightness adjustment value, which is suitable for dynamic display characteristics unique to a display panel 11 and corresponds to the brightness value of a current frame and the brightness value of a previous frame, is extracted from a look-up table LUT. A correction calculation section 12 calculates the optimal brightness value of the display panel 11 on the basis of the brightness adjustment value outputted from the look-up table LUT, and a driving section 13 drives the display panel 11 by the optimal brightness value calculated by the correction calculation section 12. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an image processing apparatus that can be suitably implemented in order to improve the display quality of a moving image of a display panel such as a liquid crystal panel.

  FIG. 1 is a diagram for explaining a technique for improving the moving image characteristics of a display panel according to the prior art. FIG. 1 (1) shows frames P1 and P2 that are adjacent in time series, and FIG. 1 schematically shows a luminance adjustment value d by underdrive with respect to the luminance, FIG. 1C schematically shows a luminance adjustment value d by overdrive with respect to the luminance, and FIG. 1D shows the luminance value of the current frame P1. The calculation procedure of the brightness adjustment value d calculated based on the brightness value of the previous frame P2 is shown. FIG. 1 (5) shows a lookup table in which the brightness value of the previous frame P2 and the brightness value of the current frame P1 are set. Show. The brightness value of the current frame P1 and the brightness value of the previous frame P2 one frame before are decomposed into, for example, 64 levels, and the set brightness adjustment value d is read for each value and added to the brightness value of the current frame P1. By doing so, the optimum luminance value is calculated. The display panel is driven by the optimum luminance value calculated in this way.

  FIG. 2 is a diagram for explaining a processing procedure of image data by a conventional image processing apparatus. The luminance adjustment value d determined based on the luminance value of the current frame P1 captured as input image data and the luminance value of the previous frame P2 one frame before is the upper 6 bits of each 8-bit luminance value (12 in total) Bit) is a value corresponding to an address, and is stored in the storage unit 1 in advance as stored data. The storage unit 1 is realized by a RAM (Random Access Memory).

  The control unit extracts a luminance adjustment value d suitable for the temperature of the use environment of the display panel from the plurality of luminance adjustment values stored in the storage unit 1, and the extracted 8-bit luminance value is sign-extended. Thus, the upper 2 bits are complemented, added to the luminance value of the current frame P1 in the correction calculation unit 2, and output as the optimum luminance value, and the display panel is driven by this optimum luminance value.

  Such a prior art is described in Patent Document 1, for example. This conventional technology realizes high-definition video display by accurately predicting the temperature of display panels such as LCD (Liquid Crystal Display) and determining the overdrive value, which is a luminance value, and under the usage environment. There has been proposed an image processing device that realizes overdrive driving suitable for a use environment after manufacture by measuring the response speed of the display panel and optimizing the overdrive value.

  Another conventional technique is described in Patent Document 2, for example. In this conventional technology, the ambient temperature of the display panel is measured, the overdrive value corresponding to the start level of the liquid crystal and the target gray level of the liquid crystal are extracted from the lookup table, and the temperature adaptive algorithm is applied to the extracted overdrive value And an adaptive overdrive value is determined. The adaptive overdrive value adjusts the difference between the measured ambient temperature and the reference temperature, and uses the appropriate overdrive value to drive the LCD to achieve the desired responsiveness.

  The overdrive value in the look-up table corresponds to the gray level transition between the previous frame and the current frame, and indicates the level at which the liquid crystal should be driven to achieve the desired response time for the gray level transition at a certain reference temperature. Represent. The processor extracts an overdrive value corresponding to the gray level transition between the previous frame and the current frame from the lookup table, and calculates an adaptive overdrive value that adjusts for the difference between the measured ambient temperature and the reference temperature. . Thus, in this prior art, the obtained adaptive overdrive value allows image processing to achieve desirable response times and reduce memory capacity without the need for multiple look-up tables calibrated at different reference temperatures. A device has been proposed.

JP 2007-219392 A JP 2008-242458 A

Each of the prior arts of Patent Documents 1 and 2 is configured to extract an overdrive value that can optimize the moving image display characteristics with respect to a change in the use environment of the display panel, from a lookup table. A change in brightness around the display panel is not configured to be reflected in the overdrive value. The overdrive values are VGA (Video Graphics Array), EGA (Enhanced Graphics Adapter), WVGA (Wide Video).
It is not set according to the type of display panel such as (Graphics Array), so it will be reflected even if the ambient brightness varies depending on the usage environment such as morning, noon, evening, or sunny, cloudy, rainy etc. Therefore, there is a problem that an optimum luminance value cannot be obtained, and therefore high display quality for a moving image cannot be realized.

  An object of the present invention is to provide an image processing apparatus capable of displaying a moving image with high quality in accordance with the type and use environment of a display panel.

The present invention (1) includes a table storing brightness adjustment values suitable for dynamic display characteristics unique to the display panel,
A correction calculation unit that calculates an optimal luminance value of the display panel based on the luminance adjustment value extracted from the table and corresponding to the luminance value of the current frame and the luminance value of the previous frame;
An image processing apparatus comprising: a drive unit that drives the display panel using the optimum luminance value calculated by the correction calculation unit.

  According to the present invention (1), the table outputs a brightness adjustment value suitable for the dynamic display characteristic unique to the display panel. The correction calculation unit calculates the optimum luminance value of the display panel based on the luminance adjustment value output from the table and corresponding to the luminance value of the current frame and the luminance value of the previous frame. Therefore, the drive unit can drive the display panel with the optimum luminance value calculated by the correction calculation unit, and can realize a high-quality moving image display without deterioration.

Further, the present invention (2) includes a table in which brightness adjustment values suitable for dynamic display characteristics are stored on the display panel according to the brightness of the usage environment,
A correction calculation unit that calculates an optimal luminance value of the display panel based on the luminance adjustment value extracted from the table and corresponding to the luminance value of the current frame and the luminance value of the previous frame;
An image processing apparatus comprising: a drive unit that drives the display panel using the optimum luminance value calculated by the correction calculation unit.

  According to the present invention (2), the table outputs a brightness adjustment value suitable for the dynamic display characteristics according to the brightness of the usage environment of the display panel. The correction calculation unit calculates the optimum luminance value of the display panel based on the luminance adjustment value output from the table and corresponding to the luminance value of the current frame and the luminance value of the previous frame. Therefore, the drive unit can drive the display panel with the optimum luminance value calculated by the correction calculation unit, and can realize a high-quality moving image display without deterioration.

  According to the present invention (1), since the display panel is driven by the drive unit with the optimum luminance value suitable for the dynamic display characteristic unique to the display panel, the display panel is unique to the display panel regardless of the display panel model. It is possible to dynamically display an image with a luminance value optimum for the moving image display characteristics, thereby realizing a clear moving image display without blur. In addition, since the display panel is driven with the optimum luminance value corresponding to the brightness of the usage environment of the display panel, it is possible to realize a good moving image display in which no blur occurs.

  Further, according to the present invention (2), the display panel is driven by the drive unit with the optimum luminance value suitable for the dynamic display characteristics in accordance with the brightness of the display panel usage environment. In addition, it is possible to dynamically display an image with a luminance value optimum for the moving image display characteristic unique to the display panel, thereby realizing a clear moving image display without blur. In addition, since the display panel is driven with the optimum luminance value corresponding to the brightness of the usage environment of the display panel, it is possible to realize a good moving image display in which no blur occurs.

  FIG. 3 is a block diagram showing an image processing apparatus 10 according to an embodiment of the present invention, and FIG. 4 is a diagram for explaining a processing procedure of image data by the image processing apparatus 10. The image processing apparatus 10 of the present embodiment extracts, from the lookup table LUT, luminance adjustment values that are suitable for dynamic display characteristics unique to the display panel 11 and that correspond to the luminance value of the current frame and the luminance value of the previous frame. Based on the extraction unit 15, the look-up table LUT in which the brightness adjustment value suitable for the dynamic display characteristic unique to the display panel 11 is set, and the brightness adjustment value output from the look-up table LUT, the display panel 11. The correction calculation unit 12 that calculates the optimal luminance value of the display unit 11 and the drive unit 13 that drives the display panel 11 with the optimal luminance value calculated by the correction calculation unit 12 are included. Such an image processing apparatus 10 is realized by a computer.

  The display panel 11 is realized by a liquid crystal display in which a liquid crystal cell having a thin film transistor (abbreviated as TFT) as an active element is operated in a normally black mode by an image signal having an optimum luminance value from the driving unit 13.

  The luminance value of the current frame and the luminance value of the previous frame one frame before are input to the lookup table LUT. The luminance value of the current frame and the luminance value of the previous frame are represented by 8 bits (256 gradations), and the lookup table LUT is a 12-bit address signal determined from the upper 6 bits of each input luminance value. A corresponding 8-bit luminance correction value is extracted.

  The brightness correction value stores a plurality of brightness adjustment values according to the type of display panel 11 such as VGA (Video Graphics Array), EGA (Enhanced Graphics Adapter), and WVGA (Wide Video Graphics Array). Has been. The lookup table LUT is realized by a RAM (Random Access Memory).

  The correction calculation unit 12 extracts a luminance adjustment value suitable for the moving image display characteristic of the display panel 11 from the plurality of luminance adjustment values stored in the lookup table LUT, and the extracted 8-bit luminance value is By sign extension, the upper 2 bits are complemented and added to the luminance value of the current frame in the correction calculation unit 12 to be output as a 10-bit optimum luminance value.

  In this optimum luminance value, the 8th bit data indicates whether the luminance value overflows, that is, whether it exceeds the upper limit (= 255) at 255 gradations, and the 9th bit data has an undervalued luminance value. It represents whether or not it is a flow, that is, whether or not it is lower than the lower limit (= 0) in 255 gradations. In the present embodiment, when the eighth bit is “1”, the luminance value is set to the upper limit value, and when the ninth bit is “1”, the luminance value is set to the lower limit value. When both bits are “0”, the luminance value is set to a halftone (= 1 to 254), and the display panel 11 is driven by such an optimal luminance value.

FIG. 5 is a diagram for explaining a method of measuring the image display characteristics of the image processing apparatus 10, FIG. 6 is a diagram showing a measurement pattern used for measuring the image display characteristics, and FIG. 7 is a measurement of the image display characteristics. It is a figure which shows the image used for. The inventor of the present invention has high relevance and linkage with the actual video visibility as one of the indexes indicating the image display characteristics of the image processing apparatus 10 according to the present invention, here, the degree of blur in moving image display. VESA (Video Electronics
A test image 20 shown in FIG. 5 is taken with a video follow-up camera based on a standard related to video display characteristics standardized by the Standards Association, and MPRT (Moving
Picture Response Time) was calculated. Actually, the adjustment value is determined not only by the MPRT value but also by actually visually confirming various images, and a small MPRT value cannot generally be said to be the best image. The adjustment value is determined by both confirmations.

  The test image 20 is obtained by photographing the blur width of the edge portion 24 as a boundary while scrolling the black area 21 with high density and the white areas 22 and 23 with low density on both sides thereof from left to right as shown in FIG. Then, the response time was calculated from the moving speed of the black area 21, and the average value was measured by changing the luminance and moving speed of the white areas 22 and 23. The test image 20 was measured for 42 sets of images obtained by dividing the entire range from all white to all black by combining seven gradations into six.

FIG. 8A is a graph showing a change in adjustment time when the luminance value is not drive-controlled, and FIG. 8B is a graph showing a change in adjustment time when the luminance value is drive-controlled. FIG. 9 is a graph showing that the blur time is reduced by correcting the luminance. 8A and 8B, the vertical axis represents luminance (Cdm ² ), and the horizontal axis represents adjustment time. FIG. 9 (1) shows the blur time when drive control is not performed, and FIG. 9 (2) shows the blur time when drive control is performed.

  As an overdrive voltage applied to a frame that switches from a halftone to a brighter gradation, a voltage higher than the gradation voltage after switching is usually applied, but a lower voltage is applied (that is, underdrive processing). The blur of the edges of the video may be improved. This is because the response characteristics of the liquid crystal of the switched frame differ depending on the combination of gradations before and after switching, and the moving image edge position varies.

  In this embodiment, in order to correct the response delay of the liquid crystal, the luminance adjustment value is extracted as described above, and an overdrive voltage or an underdrive voltage corresponding to the optimum luminance value is applied to the pixel at the time of frame transition. Apply. Thereby, the moving image quality of the display panel 11 can be improved, and motion blur and blur can be reduced.

  According to such a configuration, the lookup table LUT outputs a luminance adjustment value suitable for the dynamic display characteristic unique to the display panel 11 based on the luminance value of the current frame and the luminance value of the previous frame. The correction calculation unit 12 calculates the optimum luminance value of the display panel 11 based on the luminance adjustment value output from the lookup table LUT. Therefore, the drive unit 13 can drive the display panel 11 with the optimum luminance value calculated by the correction calculation unit 12, and can realize a high-quality moving image display without deterioration.

  FIG. 10 is a diagram showing a processing procedure of image data by the image processing apparatus 10a according to another embodiment of the present invention. Note that portions corresponding to those of the above-described embodiment are denoted by the same reference numerals, and description thereof is omitted to avoid duplication. The image processing apparatus 10a according to the present embodiment is suitable for dynamic display characteristics according to the brightness in the usage environment of the display panel 11 detected by the brightness detection sensor 16, and the brightness value of the current frame and the brightness value of the previous frame. A brightness adjustment value corresponding to the lookup table LUT, the extraction unit 15 for extracting the brightness adjustment value from the lookup table LUT, and the brightness adjustment value output from the lookup table LUT. The correction calculation unit 12 that calculates the optimal luminance value of the panel 11, the selector 27 that selects a luminance adjustment value suitable for the dynamic display characteristics according to the brightness of the usage environment, and the optimal luminance calculated by the correction calculation unit 12 And a drive unit 13 that drives the display panel 11 according to values. Such an image processing apparatus 10a is realized by a computer.

  FIG. 11 is a diagram for explaining the brightness level switching operation of the selector 27. The selector 27 detects a brightness level of a use environment in which the display panel 11 is installed, based on a brightness signal from a photodetector 28 installed in the display panel 11 or in the vicinity thereof. One look-up table LUT is selected from a plurality of look-up tables LUT created according to the brightness level, and a corrected luminance value having the same address is extracted from the look-up table LUT of the selected brightness level.

  According to such a configuration, the selector 27 is suitable for dynamic display characteristics according to the brightness of the use environment of the display panel 11 from the look-up table LUT, and converts the luminance value of the current frame and the luminance value of the previous frame. Outputs the corresponding brightness adjustment value. The correction calculation unit 12 calculates the optimum luminance value of the display panel 11 based on the luminance adjustment value output from the lookup table LUT. Therefore, the drive unit 13 can drive the display panel 11 with the optimum luminance value calculated by the correction calculation unit 12, and can realize a high-quality moving image display without deterioration.

It is a figure for demonstrating the method for improving the moving image characteristic of the display panel of a prior art, FIG. 1 (1) shows the adjacent frames P1 and P2 in time series, FIG. The brightness adjustment value d by underdrive is schematically shown. FIG. 1 (3) schematically shows the brightness adjustment value d by overdrive with respect to the brightness. FIG. 1 (4) shows the brightness value of the current frame P1 and the previous frame P2. FIG. 1 (5) shows a lookup table in which the luminance value of the previous frame P2 and the luminance value of the current frame P1 are set. It is a figure for demonstrating the process sequence of the image data by the image processing apparatus of a prior art. 1 is a block diagram illustrating an image processing apparatus 10 according to an embodiment of the present invention. FIG. 3 is a diagram for explaining a processing procedure of image data by the image processing apparatus 10. 3 is a diagram for explaining a method of measuring image display characteristics of the image processing apparatus 10. FIG. It is a figure which shows the measurement pattern used for a measurement of an image display characteristic. It is a figure which shows the image used for a measurement of an image display characteristic. It is a graph showing the change of the adjustment time when not carrying out drive control of a luminance value. It is a graph showing the change of the adjustment time at the time of drive-controlling a luminance value. FIG. 9A is a graph showing that the blur time is reduced by correcting the luminance, FIG. 9A shows the blur time when drive control is not performed, and FIG. 9B is the blur time when drive control is performed. Indicates. It is a figure which shows the process sequence of the image data by the image processing apparatus 10a of other embodiment of this invention. It is a figure for demonstrating the switching operation of the brightness level of the selector 27. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10, 10a Image processing apparatus 11 Display panel 12 Correction | amendment calculating part 13 Drive part 20 Test image LUT Look-up table

Claims (4)

A table storing brightness adjustment values suitable for dynamic display characteristics unique to the display panel;
A correction calculation unit that calculates an optimal luminance value of the display panel based on the luminance adjustment value extracted from the table and corresponding to the luminance value of the current frame and the luminance value of the previous frame;
An image processing apparatus comprising: a drive unit that drives the display panel using the optimum luminance value calculated by the correction calculation unit. A table storing brightness adjustment values suitable for dynamic display characteristics according to the brightness of the usage environment on the display panel;
A correction calculation unit that calculates an optimal luminance value of the display panel based on the luminance adjustment value extracted from the table and corresponding to the luminance value of the current frame and the luminance value of the previous frame;
An image processing apparatus comprising: a drive unit that drives the display panel using the optimum luminance value calculated by the correction calculation unit.   3. The image processing apparatus according to claim 1, wherein a value with the smallest MPRT value is set as a luminance adjustment value in the table. 4.   4. The image according to claim 1, wherein the table is set as a brightness adjustment value with a value at which the display panel has an optimum dynamic display characteristic in accordance with a time zone. Processing equipment.