WO2008018006A2 - Image rate increasing - Google Patents
Image rate increasing Download PDFInfo
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- WO2008018006A2 WO2008018006A2 PCT/IB2007/053088 IB2007053088W WO2008018006A2 WO 2008018006 A2 WO2008018006 A2 WO 2008018006A2 IB 2007053088 W IB2007053088 W IB 2007053088W WO 2008018006 A2 WO2008018006 A2 WO 2008018006A2
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- WIPO (PCT)
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- rate increasing
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Classifications
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- G—PHYSICS
- G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
- G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
- G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
- G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
- G09G3/34—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters by control of light from an independent source
- G09G3/36—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters by control of light from an independent source using liquid crystals
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- G—PHYSICS
- G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
- G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
- G09G2320/00—Control of display operating conditions
- G09G2320/02—Improving the quality of display appearance
- G09G2320/0252—Improving the response speed
-
- G—PHYSICS
- G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
- G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
- G09G2320/00—Control of display operating conditions
- G09G2320/02—Improving the quality of display appearance
- G09G2320/0261—Improving the quality of display appearance in the context of movement of objects on the screen or movement of the observer relative to the screen
Definitions
- the invention relates to image rate increasing.
- BACKGROUND OF THE INVENTION LCD displays typically suffer from motion blur, caused by a slow response time of the liquid crystal material and the hold time of the picture. In order to reduce motion blur, the hold time of the display can be reduced. Typically, increasing the refresh rate reduces the hold time of a display.
- Various techniques for generating the extra frames to achieve a higher refresh rate have been disclosed, such as black frame insertion, grey frame insertion and dynamic frame insertion. The latter one (DFI) has been disclosed by Han-Feng Chen, et. al., Smooth Frame Insertion Method for Motion-Blur Reduction in LCDs, Samsung Electronics Co., Ltd., EuroDisplay 2005, using the name Smooth Frame Insertion.
- the DFI method doubles the frame rate of a video stream by alternatingly showing blurred and peaked pictures derived from the input pictures.
- the blurred and peaked pictures are created such that the average of the peaked and blurred image is equal to the input picture.
- DFI reduces the hold time of spatial details by a factor of 2, resulting in less motion blur, while the large areas remain at the original hold time, preventing flicker.
- the DFI solution has the disadvantage that alternating blurred and peaked frames increases the frame-by- frame picture differences, which has a negative influence on the LCD panel behavior. This leads to a decrease of the LCD panel performance and the visibility of artifacts for near black and/or near white picture details. These artifacts are often more visible and annoying than motion blur.
- the invention reduces the visibility of artifacts by reducing the alternating frame differences for near black and/or near white picture details. This is done by mixing the input picture with the DFI result based on the local luminance of the input picture. By defining a proper mixing function the optimal trade-off between artifacts and motion blur visibility can be obtained.
- Fig. 1 shows a block diagram of a basic dynamic frame insertion
- Fig. 2 shows a block diagram of a luminance-dependent dynamic frame insertion in accordance with an embodiment of the present invention
- Fig. 3 shows a mixing profile for use in the embodiment of Fig. 2.
- Fig. 1 shows a basic implementation of the DFI algorithm.
- An input picture I is applied to a low-pass filter LPF and to a non-inverting input, multiplying by 2, of a subtracter ⁇ l.
- An output of the subtracter ⁇ l is a first output signal A.
- An output of the low- pass filter LPF is a second output signal B, and is applied to an inverting input of the subtracter ⁇ l .
- each input image I is converted to a peaked picture A and a blurred image B, which are displayed one after the other so as to obtain an image rate doubling.
- Fig. 2 differs from the circuit of Fig. 1 in that the output of the low-pass filter LPF is applied to a first input, multiplying by a factor (1- ⁇ ), of an adder ⁇ 2, which also has a second input, multiplying by a factor ⁇ , receiving the input signal I.
- the output of the adder ⁇ 2 is then connected as the output of the low-pass filter LPF was connected in Fig. 1.
- Another expression for an adder with weighed inputs is a mixer.
- Fig. 2 adds a controlled mixing of the input picture I with A and B where the mixing factor ⁇ is a function of the luminance of the input picture I such that
- B ⁇ x I + (l- ⁇ ) x LP, with LP being the low-pass filtered input picture.
- the mixing function is chosen as sketched in Fig. 3, where n and m are LCD panel-specific parameters, n is chosen as low as possible and m is chosen as high as possible such that DFI performance is maximized, while LCD panel artifacts are not visible.
- one aspect of the invention relates to improvements on the Dynamic Frame Insertion method that increases the picture rate of a video stream, in order to reduce the motion blur due to the LCD's sample and hold principle.
- the improvements include a luminance-dependent mixing of input and the low-pass filtered image.
- the invention can be applied in video processing pipelines for TV systems, e.g. backend-scaler ICs on the small-signal board of an LCD-TV or TCON ICs on the LCD panel itself.
- the invention is preferably applied to RGB signals, but may alternatively be applied to a composite video signal, to YUV signals or to the Y signal only.
- any reference signs placed between parentheses shall not be construed as limiting the claim.
- the word "comprising” does not exclude the presence of elements or steps other than those listed in a claim.
- the word “a” or “an” preceding an element does not exclude the presence of a plurality of such elements.
- the invention may be implemented by means of hardware comprising several distinct elements, and/or by means of a suitably programmed processor. In the device claim enumerating several means, several of these means may be embodied by one and the same item of hardware.
- the mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.
Abstract
An image rate increasing device, comprising a low-pass filter (LPF) coupled to receive an input signal (I) to provide a low-pass filtered signal (LP), a mixer (Σ2) for mixing the low-pass filtered signal (LP) and the input signal (I) to obtain a first output signal (B) with a mixing factor (α) depending on the input signal (I), and a sharpening filter (∑l) coupled to receive the input signal (I) for obtaining a second output signal (A). This image rate increasing device is advantageously used in a display device that further comprises a display unit for sequentially displaying the first (B) and second (A) output signals.
Description
Image rate increasing
FIELD OF THE INVENTION
The invention relates to image rate increasing.
BACKGROUND OF THE INVENTION LCD displays typically suffer from motion blur, caused by a slow response time of the liquid crystal material and the hold time of the picture. In order to reduce motion blur, the hold time of the display can be reduced. Typically, increasing the refresh rate reduces the hold time of a display. Various techniques for generating the extra frames to achieve a higher refresh rate have been disclosed, such as black frame insertion, grey frame insertion and dynamic frame insertion. The latter one (DFI) has been disclosed by Han-Feng Chen, et. al., Smooth Frame Insertion Method for Motion-Blur Reduction in LCDs, Samsung Electronics Co., Ltd., EuroDisplay 2005, using the name Smooth Frame Insertion.
The DFI method doubles the frame rate of a video stream by alternatingly showing blurred and peaked pictures derived from the input pictures. The blurred and peaked pictures are created such that the average of the peaked and blurred image is equal to the input picture. As such DFI reduces the hold time of spatial details by a factor of 2, resulting in less motion blur, while the large areas remain at the original hold time, preventing flicker. The DFI solution has the disadvantage that alternating blurred and peaked frames increases the frame-by- frame picture differences, which has a negative influence on the LCD panel behavior. This leads to a decrease of the LCD panel performance and the visibility of artifacts for near black and/or near white picture details. These artifacts are often more visible and annoying than motion blur.
SUMMARY OF THE INVENTION It is, inter alia, an object of the invention to provide an improved image rate increasing. The invention is defined by the independent claims. Advantageous embodiments are defined in the dependent claims.
In one embodiment, the invention reduces the visibility of artifacts by reducing the alternating frame differences for near black and/or near white picture details.
This is done by mixing the input picture with the DFI result based on the local luminance of the input picture. By defining a proper mixing function the optimal trade-off between artifacts and motion blur visibility can be obtained.
These and other aspects of the invention will be apparent from and elucidated with reference to the embodiments described hereinafter.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 shows a block diagram of a basic dynamic frame insertion; Fig. 2 shows a block diagram of a luminance-dependent dynamic frame insertion in accordance with an embodiment of the present invention; and
Fig. 3 shows a mixing profile for use in the embodiment of Fig. 2.
DESCRIPTION OF EMBODIMENTS
Fig. 1 shows a basic implementation of the DFI algorithm. An input picture I is applied to a low-pass filter LPF and to a non-inverting input, multiplying by 2, of a subtracter ∑l. An output of the subtracter ∑l is a first output signal A. An output of the low- pass filter LPF is a second output signal B, and is applied to an inverting input of the subtracter ∑l . As a result, each input image I is converted to a peaked picture A and a blurred image B, which are displayed one after the other so as to obtain an image rate doubling. Note that A = 2 x I - B, so that the average output signal equals the input signal: (A+B)/2 = I. By subtracting a low-pass filtered signal from an input signal, the subtracter ∑l acts as a sharpening filter.
The embodiment of Fig. 2 differs from the circuit of Fig. 1 in that the output of the low-pass filter LPF is applied to a first input, multiplying by a factor (1- α), of an adder Σ2, which also has a second input, multiplying by a factor α, receiving the input signal I. The output of the adder Σ2 is then connected as the output of the low-pass filter LPF was connected in Fig. 1. Another expression for an adder with weighed inputs is a mixer.
The embodiment of Fig. 2 adds a controlled mixing of the input picture I with A and B where the mixing factor α is a function of the luminance of the input picture I such that
A = (2-α) x I - (1- α) x LP and
B = α x I + (l- α) x LP, with LP being the low-pass filtered input picture.
The mixing function is chosen such that the signal range of the input picture maps to a value for α for each input pixel between 0 and 1, where α = 0 results in an output signal identical to Fig. 1 and α = 1 results in A = I and B = I. Typically the mixing function is chosen as sketched in Fig. 3, where n and m are LCD panel-specific parameters, n is chosen as low as possible and m is chosen as high as possible such that DFI performance is maximized, while LCD panel artifacts are not visible. Clearly, alternative mixing functions are possible, which preferably follow the principle that for intermediate values of the input signal the known dynamic frame insertion method is given more weight, while for extreme values of the input signal, the input signal is given more weight. On the basis of the selected mixing function, a skilled person can easily program a look-up table so as to obtain the desired result.
In sum, one aspect of the invention relates to improvements on the Dynamic Frame Insertion method that increases the picture rate of a video stream, in order to reduce the motion blur due to the LCD's sample and hold principle. In an embodiment, the improvements include a luminance-dependent mixing of input and the low-pass filtered image. The invention can be applied in video processing pipelines for TV systems, e.g. backend-scaler ICs on the small-signal board of an LCD-TV or TCON ICs on the LCD panel itself.
It should be noted that the above-mentioned embodiments illustrate rather than limit the invention, and that those skilled in the art will be able to design many alternative embodiments without departing from the scope of the appended claims. It is possible that one input image is used to obtain more than two (e.g. 3) output images, and that two input images are used to obtain less than four (e.g. 3 in a 50 to 75 Hz conversion) output images. In the claims, the first output signal B is not necessarily displayed before the second output signal A; the reverse order is equally possible. While in the preceding embodiments a subtracter ∑l is used to obtain the peaked signal A, it is alternatively possible to use other sharpening filters, such as a high-pass filter. Preferably, such alternative sharpening filter is controlled by α so that the relation (A+B)/2 = I still holds. The invention is preferably applied to RGB signals, but may alternatively be applied to a composite video signal, to YUV signals or to the Y signal only. In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. The word "comprising" does not exclude the presence of elements or steps other than those listed in a claim. The word "a" or "an" preceding an
element does not exclude the presence of a plurality of such elements. The invention may be implemented by means of hardware comprising several distinct elements, and/or by means of a suitably programmed processor. In the device claim enumerating several means, several of these means may be embodied by one and the same item of hardware. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.
Claims
1. An image rate increasing device, comprising: a low-pass filter (LPF) coupled to receive an input signal (I) to provide a low- pass filtered signal (LP); a mixer (Σ2) for mixing the low-pass filtered signal (LP) and the input signal (I) to obtain a first output signal (B) with a mixing factor (α) depending on the input signal (I); and a sharpening filter (∑l) coupled to receive the input signal (I) for obtaining a second output signal (A).
2. An image rate increasing device as claimed in claim 1, wherein the mixing factor (α) has a first mixing factor value for first and second input values of the input signal (I), and a second mixing factor value for values of the input signal (I) between said first and second input values of the input signal (I), the second mixing factor value being smaller than the first mixing factor value.
3. An image rate increasing device as claimed in claim 1, wherein the sharpening filter (∑l) includes a subtracter (∑l) coupled to receive the first output signal (B) and the input signal (I) for obtaining the second output signal (A).
4. A display device, comprising an image rate increasing device as claimed in any of the preceding claims, and a display unit for sequentially displaying the first (B) and second (A) output signals.
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US82186106P | 2006-08-09 | 2006-08-09 | |
US60/821,861 | 2006-08-09 |
Publications (2)
Publication Number | Publication Date |
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WO2008018006A2 true WO2008018006A2 (en) | 2008-02-14 |
WO2008018006A3 WO2008018006A3 (en) | 2008-08-21 |
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PCT/IB2007/053088 WO2008018006A2 (en) | 2006-08-09 | 2007-08-06 | Image rate increasing |
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Cited By (5)
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WO2009083926A2 (en) * | 2007-12-28 | 2009-07-09 | Nxp B.V. | Arrangement and approach for image data processing |
WO2009083925A1 (en) * | 2007-12-28 | 2009-07-09 | Nxp B.V. | Arrangement and approach for motion-based image data processing |
WO2009147614A1 (en) * | 2008-06-02 | 2009-12-10 | Nxp B.V. | Artifact masking for temporal up-conversion |
JP2014011501A (en) * | 2012-06-27 | 2014-01-20 | Canon Inc | Image processing apparatus and image processing method |
CN103632346A (en) * | 2013-11-27 | 2014-03-12 | 广东威创视讯科技股份有限公司 | Method and device for realizing digital video image sharpness adjustment |
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US6281933B1 (en) * | 1997-12-11 | 2001-08-28 | Chrontel, Inc. | Images in interlaced formats: a novel method of scan conversion for video imaging systems |
EP1239450A2 (en) * | 2001-03-09 | 2002-09-11 | Thomson Licensing S.A. | Reducing sparkle artifacts with low brightness filtering |
JP2002351382A (en) * | 2001-03-22 | 2002-12-06 | Victor Co Of Japan Ltd | Display device |
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Cited By (8)
Publication number | Priority date | Publication date | Assignee | Title |
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WO2009083926A2 (en) * | 2007-12-28 | 2009-07-09 | Nxp B.V. | Arrangement and approach for image data processing |
WO2009083925A1 (en) * | 2007-12-28 | 2009-07-09 | Nxp B.V. | Arrangement and approach for motion-based image data processing |
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US8531610B2 (en) | 2007-12-28 | 2013-09-10 | Entropic Communications, Inc. | Arrangement and approach for image data processing |
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JP2014011501A (en) * | 2012-06-27 | 2014-01-20 | Canon Inc | Image processing apparatus and image processing method |
CN103632346A (en) * | 2013-11-27 | 2014-03-12 | 广东威创视讯科技股份有限公司 | Method and device for realizing digital video image sharpness adjustment |
Also Published As
Publication number | Publication date |
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WO2008018006A3 (en) | 2008-08-21 |
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