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EP2188775A2 - Method and device for improving chrominance sharpness - Google Patents

Method and device for improving chrominance sharpness

Info

Publication number
EP2188775A2
EP2188775A2 EP08807264A EP08807264A EP2188775A2 EP 2188775 A2 EP2188775 A2 EP 2188775A2 EP 08807264 A EP08807264 A EP 08807264A EP 08807264 A EP08807264 A EP 08807264A EP 2188775 A2 EP2188775 A2 EP 2188775A2
Authority
EP
European Patent Office
Prior art keywords
signal
steepness
incoming
gain
sharpness
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP08807264A
Other languages
German (de)
French (fr)
Inventor
Volker Blume
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Trident Microsystems (Far East) Ltd
Original Assignee
NXP BV
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by NXP BV filed Critical NXP BV
Priority to EP08807264A priority Critical patent/EP2188775A2/en
Publication of EP2188775A2 publication Critical patent/EP2188775A2/en
Withdrawn legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N9/00—Details of colour television systems
    • H04N9/64—Circuits for processing colour signals
    • H04N9/646—Circuits for processing colour signals for image enhancement, e.g. vertical detail restoration, cross-colour elimination, contour correction, chrominance trapping filters
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
    • G06T5/00—Image enhancement or restoration
    • G06T5/73—Deblurring; Sharpening
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
    • G06T2207/00—Indexing scheme for image analysis or image enhancement
    • G06T2207/10—Image acquisition modality
    • G06T2207/10016—Video; Image sequence
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
    • G06T2207/00—Indexing scheme for image analysis or image enhancement
    • G06T2207/10—Image acquisition modality
    • G06T2207/10024—Color image
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
    • G06T2207/00—Indexing scheme for image analysis or image enhancement
    • G06T2207/20—Special algorithmic details
    • G06T2207/20172—Image enhancement details
    • G06T2207/20192—Edge enhancement; Edge preservation

Definitions

  • the invention relates to a method for improving chrominance sharpness and an electronic device to use the method.
  • Such CTI method is disclosed by EP 0 805 603 Al where three signals are created and processed while a device creates a median of the three created signals.
  • the above mentioned problems is solved by a method for improving chrominance sharpness of an incoming signal, wherein the signal is split into its frequency spectrum components, the filtered signal is amplified according to the steepness of the incoming edge of the signal and the amplified signal is clipped on a predetermined range of the transient.
  • This method allows the improvement of the crominance sharpness while every component of the incoming signal can be processed individually and independently from each other without any interference of signal contributions.
  • the method further includes the use of a colour band pass filter to select the respective frequencies of the incoming signal.
  • the steepness dependent amplification of the signal is performed using a fixed gain below a predetermined steepness, a linear increase of the gain with increasing steepness and a maximum gain above a predetermined value of the steepness.
  • an other functionality can be used instead of the linear relationship between steepness and gain, e.g. a quadratic or a non- linear function.
  • the object of the invention regarding a device to achieve the improvement is solved by an electronic device for improving chrominance sharpness of an incoming signal, wherein the device contains a colour band pass filter to split the signal into its frequency spectrum components, further containing an amplifier to amplify the filtered signal according to the steepness of the incoming edge of the signal and a clipping device to clip the amplified signals on a predetermined range of the transient.
  • the device contains a colour band pass filter to split the signal into its frequency spectrum components, further containing an amplifier to amplify the filtered signal according to the steepness of the incoming edge of the signal and a clipping device to clip the amplified signals on a predetermined range of the transient.
  • the device is very advantageous that the device is realised within an electronic microchip.
  • At least the filter is implemented as software product within the microchip.
  • Fig. 1 shows a block diagram
  • Fig. 2 shows a block diagram
  • Fig. 3 shows a diagram
  • Fig. 4 shows a diagram
  • Fig. 1 shows a block diagram 1 to explain the peaking process.
  • Peaking is a linear methodology which means that additional frequencies can not be added to a signal spectrum of an incoming signal 2.
  • Peaking mainly consist of a linear filter 3 like a HP-Filter, which boost the middle or higher frequency part of an incoming signal 2 spectrum of an incoming signal to create an output signal 4.
  • Peaking is a well known methodology for improving the subjective impressed sharpness of images and video signals 2. Normally peaking is reserved for the use on Luminance signals only. In that domain even the non linear methodology of Transient Improvement is well established, known as LTI. LTI benefits from the non linear adaptation of the peaking principle. The counterpart in the chrominance domain is the so called Chrominance Transient Improvement (CTI) and its digital representation was designed according to its analogue predecessor.
  • CTI Chrominance Transient Improvement
  • non-linear methods can add new frequency components that are not present in the original input video signal.
  • CTI Chrominance Transient Improvement
  • the benefit of the proposed inventive CTI concept over the traditional CTI is that there is no need to determine the edge center. Edge center determination is a critical process, especially under noisy conditions, and requires sub-pixel accuracy in the discrete domain.
  • p which stands for peaking in front of the abbreviation for chrominance transient improvement that results as "pCTI”.
  • the traditional CTI is indicated as DCTI, where D stands for Digital.
  • the block diagram 10 of Fig. 2 shows the processing principle of the inventive method called pCTI.
  • Each component of the chrominance signal is processed independently from each other.
  • the incoming signal 11 is split into its frequency spectrum components by a Colour Band Pass Filter (CBPF) 12.
  • CBPF Colour Band Pass Filter
  • the filtered signal 13 is amplified with an amplifier 14 depending on the steepness of the incoming edge which is analysed in block 16 and feed to block 14. This way of processing allows the exclusion of transients with small amplitudes, which are normally typical for noise.
  • the next step in the processing order is the clipping routine 15, which clip the signal on the prior determined Minimum (Min) and Maximum (Max) level of the transient, which is determined by block 17.
  • the characteristics the amplitude as a function of frequency of the above described Colour Band Pass Filters is shown in Fig. 3, where two different CBPF filters are represented.
  • the line or curve 21 of diagram 20 represents one CBPF called SD/HD while the line or curve 22 represents a second CBPF called SD/SD HD/HD.
  • the characteristic frequency of the first filter (line 21) lies almost half times lower than the characteristic frequency of the second filter (line 22).
  • Fig. 4 shows a diagram 25 of the gain as a function of the steepness.
  • the line or curve 26 starts at a certain value of the gain 27 being constant until a predetermined value of the steepness 29 is achieved. Between the values of 29 and 30 of the steepness the gain will increase and after reaching the predetermined value 30 of the steepness the gain will be constant at a maximum gain level 28.

Landscapes

  • Engineering & Computer Science (AREA)
  • Multimedia (AREA)
  • Signal Processing (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Theoretical Computer Science (AREA)
  • Processing Of Color Television Signals (AREA)
  • Picture Signal Circuits (AREA)

Abstract

The invention relates to a method and an electronic device for improving chrominance sharpness of an incoming signal (11), wherein the signal is split into its frequency spectrum components (12), the filtered signal is amplified (14) according to the steepness of the incoming edge of the signal and the amplified signals are clipped on a predetermined range of the transient (15).

Description

Method and Device for improving Chrominance Sharpness
FIELD OF THE INVENTION
The invention relates to a method for improving chrominance sharpness and an electronic device to use the method.
BACKGROUND OF THE INVENTION
The use of images and video signals is growing due to new technologies within the field of computer technology but also in the field of data transmission. Therefore the quality of such image or video data is very important for the acceptance of a new technology or a new product. To improve the subjective impressed sharpness of images and video signals, peaking is a well known linear methodology. This peaking methodology is reserved for the use on Luminance signals only. In that domain the non linear methodology of Transient Improvement is well established, known as LTI, and benefits from the non linear adaptation of the peaking principle. The counterpart in the Chrominance domain is the Chrominance Transient Improvement (CTI) and its digital representation was designed according to its analogue implementation.
Several improvements has been made since that time, but a list of disadvantages like the sensitivity of the concept against noise and jitter couldn't be solved to an acceptable degree. Furthermore new displays with High Definition resolution demand for an video processing concept that allows to use CTI after a scaling process.
Such CTI method is disclosed by EP 0 805 603 Al where three signals are created and processed while a device creates a median of the three created signals.
Additionally US 6,909,813 B2 discloses a contour correction circuit and a contour correction method.
SUMMARY OF THE INVENTION
It is an object of the inventions to improve the crominance sharpness while achieving the improvement without additionally very high costs.
The above mentioned problems is solved by a method for improving chrominance sharpness of an incoming signal, wherein the signal is split into its frequency spectrum components, the filtered signal is amplified according to the steepness of the incoming edge of the signal and the amplified signal is clipped on a predetermined range of the transient. This method allows the improvement of the crominance sharpness while every component of the incoming signal can be processed individually and independently from each other without any interference of signal contributions.
According to an other inventive embodiment the method further includes the use of a colour band pass filter to select the respective frequencies of the incoming signal.
According to an other embodiment it is of advantage that the steepness dependent amplification of the signal is performed using a fixed gain below a predetermined steepness, a linear increase of the gain with increasing steepness and a maximum gain above a predetermined value of the steepness. But it can be further of advantage that an other functionality can be used instead of the linear relationship between steepness and gain, e.g. a quadratic or a non- linear function.
The object of the invention regarding a device to achieve the improvement is solved by an electronic device for improving chrominance sharpness of an incoming signal, wherein the device contains a colour band pass filter to split the signal into its frequency spectrum components, further containing an amplifier to amplify the filtered signal according to the steepness of the incoming edge of the signal and a clipping device to clip the amplified signals on a predetermined range of the transient.
According to an embodiment of the invention it is very advantageous that the device is realised within an electronic microchip.
Additionally it is of advantage that at least the filter is implemented as software product within the microchip.
BRIEF DESCRIPTION OF THE DRAWINGS
The above and other features and advantages of the invention will be apparent from the following description of an exemplary embodiment of the invention with reference to the accompanying drawings, in which:
Fig. 1 shows a block diagram; Fig. 2 shows a block diagram;
Fig. 3 shows a diagram; and
Fig. 4 shows a diagram.
DETAILED DESCRIPTION OF THE DRAWINGS
Fig. 1 shows a block diagram 1 to explain the peaking process. Peaking is a linear methodology which means that additional frequencies can not be added to a signal spectrum of an incoming signal 2. Peaking mainly consist of a linear filter 3 like a HP-Filter, which boost the middle or higher frequency part of an incoming signal 2 spectrum of an incoming signal to create an output signal 4.
Peaking is a well known methodology for improving the subjective impressed sharpness of images and video signals 2. Normally peaking is reserved for the use on Luminance signals only. In that domain even the non linear methodology of Transient Improvement is well established, known as LTI. LTI benefits from the non linear adaptation of the peaking principle. The counterpart in the chrominance domain is the so called Chrominance Transient Improvement (CTI) and its digital representation was designed according to its analogue predecessor. Several Improvements have been made since that time, but a list of disadvantages of the concept like the sensitivity against noise and jitter couldn't be solved.
As a result of the selective frequency boosting the so called over- and undershoots are introduced or amplified whether they are present in the signal.
Additionally non-linear methods can add new frequency components that are not present in the original input video signal. A good example of a non- linear methodology is Chrominance Transient Improvement (CTI).
The benefit of the proposed inventive CTI concept over the traditional CTI is that there is no need to determine the edge center. Edge center determination is a critical process, especially under noisy conditions, and requires sub-pixel accuracy in the discrete domain. In order to differentiate the traditional CTI concept from the new peaking based we add a "p", which stands for peaking in front of the abbreviation for chrominance transient improvement that results as "pCTI". The traditional CTI is indicated as DCTI, where D stands for Digital.
The block diagram 10 of Fig. 2 shows the processing principle of the inventive method called pCTI. Each component of the chrominance signal is processed independently from each other. The incoming signal 11 is split into its frequency spectrum components by a Colour Band Pass Filter (CBPF) 12.
The filtered signal 13 is amplified with an amplifier 14 depending on the steepness of the incoming edge which is analysed in block 16 and feed to block 14. This way of processing allows the exclusion of transients with small amplitudes, which are normally typical for noise. The next step in the processing order is the clipping routine 15, which clip the signal on the prior determined Minimum (Min) and Maximum (Max) level of the transient, which is determined by block 17.
The characteristics the amplitude as a function of frequency of the above described Colour Band Pass Filters is shown in Fig. 3, where two different CBPF filters are represented. The line or curve 21 of diagram 20 represents one CBPF called SD/HD while the line or curve 22 represents a second CBPF called SD/SD HD/HD. As it is visible from the diagram of Fig. 3 the characteristic frequency of the first filter (line 21) lies almost half times lower than the characteristic frequency of the second filter (line 22).
In case that both filters are cascaded they can be controlled individually by its gain. Fig. 4 shows a diagram 25 of the gain as a function of the steepness. The line or curve 26 starts at a certain value of the gain 27 being constant until a predetermined value of the steepness 29 is achieved. Between the values of 29 and 30 of the steepness the gain will increase and after reaching the predetermined value 30 of the steepness the gain will be constant at a maximum gain level 28. References
1 block diagram
2 incoming signal
3 filter
4 output signal
10 block diagram
11 incoming signal
12 colour band pass filter
13 filtered signal
14 amplifier
15 clipping device or routine
16 device to analyse the steepness of the incoming signal
17 block to clip the incoming signal
20 diagram
21 line/curve
22 line/curve
25 diagram
26 line/curve
27 gain
28 gain level
29 predetermined value of steepness
30 predetermined value of steepness

Claims

1. Method for improving chrominance sharpness of an incoming signal (11), wherein the signal (11) is split into its frequency spectrum components, the filtered signal is amplified according to the steepness of the incoming edge of the signal (14) and the amplified signal is clipped on a predetermined range of the transient (15).
2. Method for improving chrominance sharpness according to claim 1 further includes the use of a colour band pass filter (12) to select the respective frequencies of the incoming signal.
3. Method according to claim 1 wherein the steepness dependent amplification of the signal is performed using a fixed gain below a predetermined steepness, a linear increase of the gain with increasing steepness and a maximum gain above a predetermined value of the steepness.
4. Method according to claim 3, wherein an other functionality is used instead of the linear relationship between steepness and gain.
5. Electronic device for improving chrominance sharpness of an incoming signal, wherein the device contains a colour band pass filter (12) to split the signal into its frequency spectrum components, further containing an amplifier (14) to amplify the filtered signal according to the steepness of the incoming edge of the signal and a clipping device (15) to clip the amplified signals on a predetermined range of the transient.
6. Device according to claim 5 wherein the device is realised within an electronic microchip.
7. Device according to claim 5, wherein at least the filter is implemented as software product within the microchip.
EP08807264A 2007-08-20 2008-08-07 Method and device for improving chrominance sharpness Withdrawn EP2188775A2 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
EP08807264A EP2188775A2 (en) 2007-08-20 2008-08-07 Method and device for improving chrominance sharpness

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
EP07114583 2007-08-20
EP08807264A EP2188775A2 (en) 2007-08-20 2008-08-07 Method and device for improving chrominance sharpness
PCT/IB2008/053179 WO2009024885A2 (en) 2007-08-20 2008-08-07 Method and device for improving chrominance sharpness

Publications (1)

Publication Number Publication Date
EP2188775A2 true EP2188775A2 (en) 2010-05-26

Family

ID=40378759

Family Applications (1)

Application Number Title Priority Date Filing Date
EP08807264A Withdrawn EP2188775A2 (en) 2007-08-20 2008-08-07 Method and device for improving chrominance sharpness

Country Status (3)

Country Link
EP (1) EP2188775A2 (en)
CN (1) CN101779221B (en)
WO (1) WO2009024885A2 (en)

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8805114B2 (en) * 2012-11-27 2014-08-12 Texas Instruments Incorporated Content adaptive edge and detail enhancement for image and video processing
CN105809644B (en) * 2016-03-15 2018-05-15 深圳英飞拓科技股份有限公司 Image border fake color inhibition method and device

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0805603A1 (en) * 1996-01-11 1997-11-05 Texas Instruments Incorporated Improvements in or relating to signal processing circuits
US7271851B2 (en) * 2003-01-16 2007-09-18 Samsung Electronics Co., Ltd. Adaptive color transient improvement
SG115540A1 (en) * 2003-05-17 2005-10-28 St Microelectronics Asia An edge enhancement process and system
US7454081B2 (en) * 2004-01-30 2008-11-18 Broadcom Corporation Method and system for video edge enhancement
US7653257B2 (en) * 2005-07-19 2010-01-26 Intel Corporation Enhancing video sequence sharpness by adaptive peaking
KR100757731B1 (en) * 2006-02-16 2007-09-11 삼성전자주식회사 Method for adaptive image signal transient improvement, and image quality improvement device for the same

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO2009024885A3 *

Also Published As

Publication number Publication date
CN101779221A (en) 2010-07-14
WO2009024885A3 (en) 2009-06-25
CN101779221B (en) 2012-10-03
WO2009024885A2 (en) 2009-02-26

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