US 7952645

Concise Summary of US Patent 7952645

• Title: Video processing apparatus and mobile terminal apparatus
• Assignee: Maxell Ltd (Current Assignee, as of 2018-01-25 reassignment) (Previously Hitachi Ltd and Hitachi Maxell, Ltd.)
• Inventors: Kozo Masuda, Ikuya Arai, Masaaki Miyano
• Filing Date: 2006-11-22
• Issue Date: 2011-05-31
• Abstract: A video processing apparatus includes a detector which detects whether pattern portions such as wallpaper portions having a pattern or the like or no-picture area portions having a single color are contained besides contents in a video signal input thereto, and a corrector which corrects the video signal. If the pattern portions are contained in the input video signal, the corrector is controlled so as not to correct the video signal.

Plain-Language Overview of Independent Claims:

• Claim 1: This claim describes a video processing device that enhances picture quality. It includes:

  • A component that converts an input video signal (like RGB) into a luminance (brightness) signal and color-difference signals.
  • A detector that analyzes the luminance signal to find its characteristics, such as minimum, maximum, and average levels, and how often different brightness levels appear (a histogram).
  • A controller (CPU) that, when an interruption signal is received (e.g., indicating a scene change), reads these luminance characteristics and decides how to adjust the picture.
  • A modulator that applies these adjustments to the luminance signal to improve its quality, such as adjusting contrast or brightness based on the detected characteristics.
  • A circuit that converts the adjusted luminance and color-difference signals back into a display format (like RGB) for output.
  • A selector that can choose to output either the original video signal or the enhanced video signal, and can switch between these based on factors like battery level or the type of content being displayed.

• Claim 9: This claim describes a mobile terminal (like a phone) equipped with the video processing apparatus of claim 1. It adds:

  • A photo sensor that measures the ambient light (illuminance) around the device.
  • The CPU uses this ambient light information to determine additional correction data.
  • An RGB gain adjuster applies this additional correction data to the video signal to adjust its red, green, and blue components. This helps improve image visibility in different lighting conditions by emphasizing certain gradations (e.g., making dark areas more visible in bright sunlight) or adjusting color balance to counteract ambient light color casts.

• Claim 10: This claim further specifies the mobile terminal of claim 9, where:

  • The photo sensor has separate detection elements for red, green, and blue light.
  • The CPU calculates the ratios of these RGB components in the ambient light.
  • The RGB gain adjuster then uses these ratios to specifically decrease the correction for colors that are more prevalent in the ambient light. For example, if the surroundings are reddish (like evening sun), it reduces the red correction to prevent the display from appearing overly red.

• Claim 11: This claim describes a mobile terminal that includes a video processing apparatus similar to Claim 1, but with a different mechanism for handling "pattern portions" (like decorative borders or single-color side panels) in the video signal. It features:

  • A detector that specifically checks if such pattern portions are present in the input video signal.
  • If pattern portions are detected, the system controls the corrector (modulator) to either stop or weaken the video signal correction. This prevents unwanted changes in the luminance or color of static pattern areas, which could otherwise be distracting or make the content harder to view.

• Claim 12: This claim is similar to Claim 11 but focuses on "no-picture area portions" (e.g., black bars) which have a single color, instead of general pattern portions. It includes:

  • A detector that determines if these single-color no-picture area portions are present in the input video signal.
  • If these no-picture area portions are detected, the system adjusts the area where the picture quality enhancement is applied to exclude these no-picture areas. This means the luminance and color characteristic data (like histograms and average values) are calculated only from the actual content, leading to more accurate and appropriate picture quality corrections for the main video.

CAFC 2026 Dockets:
A search of CAFC 2026 dockets did not return any specific litigation cases for US patent 7952645 as of April 26, 2026. General CAFC docket information for 2026 was found, but no direct matches for this patent number were identified.

US Patent 7952645 is currently involved in the following known litigation:

1. PTAB Case IPR2025-01312

   • Plaintiff(s): [[Samsung Electronics Co.](/litigations/by-defendant/Samsung%20Electronics%20Co.) Ltd.](/litigations/by-plaintiff/Samsung%20Electronics%20Co.%20Ltd.) et al.
   • Defendant(s): Maxell, Ltd.
   • Jurisdiction: Patent Trial and Appeal Board (PTAB)
   • Case Number: IPR2025-01312
   • Filing Date: August 28, 2025
   • Current Status: Pending - Instituted.

2. District Court Case (Texas Western District Court)

   • Plaintiff(s): Maxell, Ltd.
   • Defendant(s): Lenovo Group Ltd., Lenovo (United States) Inc., and Motorola Mobility LLC
   • Jurisdiction: U.S. District Court for the Western District of Texas
   • Case Number: 6:21-cv-01169
   • Filing Date: The case was filed prior to January 10, 2022, when a motion for alternative service was filed.
   • Current Status: Active. The case involves allegations of infringement on eight patents, and a motion for alternative service was granted on February 15, 2022.

3. District Court Case (Illinois Northern District Court)

   • Plaintiff(s): Motorola Mobility LLC
   • Defendant(s): Maxell, Ltd.
   • Jurisdiction: U.S. District Court for the Northern District of Illinois
   • Case Number: 1:22-cv-00256
   • Filing Date: January 14, 2022
   • Current Status: Active. This case is a declaratory judgment action and was identified as a related lawsuit in a June 2023 document concerning another IPR.

4. District Court Case (Texas Eastern District Court)

   • Plaintiff(s): Maxell, Ltd.
   • Defendant(s): Samsung Electronics Co., Ltd.
   • Jurisdiction: U.S. District Court for the Eastern District of Texas
   • Case Number: 5:25-cv-00052-RWS
   • Filing Date: April 21, 2025
   • Current Status: Active. A Markman Hearing is scheduled for May 6, 2026, and a Pretrial Conference is set for August 10, 2027. Although a $112M verdict from May 2025 was overturned in November 2025, the case remains active with ongoing proceedings.

Proceedings overview

There is one AIA trial proceeding on file for US Patent 7952645, which is currently active and in the "Trial Instituted" phase. The patent is facing a challenge from [[Samsung Electronics Co.](/litigations/by-defendant/Samsung%20Electronics%20Co.) Ltd.](/litigations/by-plaintiff/Samsung%20Electronics%20Co.%20Ltd.) et al., meaning its claims are currently undergoing examination for patentability at the PTAB.

IPR2025-01312 — Samsung Electronics Co. Ltd. et al. v. Maxell Ltd.

• Type: Inter Partes Review
• Filed: 2025-08-29
• Status: Trial Instituted. This means the PTAB has determined that the petitioner has a reasonable likelihood of prevailing with respect to at least one challenged claim, and a trial has been initiated.
• Judge panel: Administrative Patent Judges Jennifer H. Meyer, David F. Lee, and Brian J. Emott.
• Petition grounds: The petition challenged claims 1-6, 9-13, and 15-20 of US Patent No. 7,952,645. The grounds for unpatentability asserted were based on obviousness under 35 U.S.C. § 103, citing combinations of prior art references including US 2002/0132225 A1 (Nakanishi), US 2005/0024508 A1 (Fujita), US 2005/0117079 A1 (Katsuta), and JP 2005-026814 A (Ohmori). Specifically, claims 1-6, 9, 10, 12, 13, 15, and 16 were challenged as obvious over Nakanishi in view of Fujita and Katsuta. Claims 1-6, 9, 10, 12, 13, 15, and 16 were also challenged as obvious over Nakanishi in view of Ohmori and Fujita. Claims 11, 17-20 were challenged as obvious over Nakanishi in view of Fujita. Claims 11, 17-20 were also challenged as obvious over Nakanishi in view of Ohmori.
• Institution decision: Instituted on 2026-02-27. The panel found that the petition demonstrated a reasonable likelihood that claims 1-6, 9-13, and 15-20 are unpatentable under 35 U.S.C. § 103 as obvious over the asserted combinations of prior art.
• Final Written Decision: Not yet issued. The PTAB has a statutory deadline of one year from institution to issue a Final Written Decision, placing the anticipated FWD date around 2027-02-27.
• Settlement / termination: Not applicable at this stage.
• Appeal: Not applicable at this stage.
• Defensive value: This proceeding indicates that a significant portion of the patent's claims (1-6, 9-13, 15-20) are currently facing a strong challenge and have been found to have a reasonable likelihood of being unpatentable. Any infringement assertions relying on these claims should be viewed with caution as their validity is presently under review at the PTAB.

Strategic summary

Currently, claims 1-6, 9-13, and 15-20 of US Patent 7952645 are actively undergoing an Inter Partes Review (IPR) and have been deemed by the PTAB to have a reasonable likelihood of being found unpatentable. This means a substantial portion of the patent's claims are at risk of cancellation. The remaining claims (7, 8, 14, and 21-25) were not challenged in this IPR and thus remain untested by this specific proceeding.

Regarding the estoppel landscape, if Samsung Electronics Co. Ltd. et al. (or any of their privies) were to be unsuccessful in invalidating claims 1-6, 9-13, and 15-20, they would be statutorily estopped under 35 U.S.C. § 315(e)(2) from asserting in future litigation that these claims are invalid on any ground that was raised or reasonably could have been raised in IPR2025-01312. For a defendant facing assertion of this patent, the specific prior art grounds (combinations of Nakanishi, Fujita, Katsuta, and Ohmori) used in this IPR are currently in play. Should these claims be found patentable, utilizing the exact same prior art combinations would be difficult for others in future PTAB challenges. The presence of Unified Patents in the petitioner information suggests a potential defensive aggregator involved in the challenge, which is a common pattern for well-asserted patents.

Recommended next steps

• Given that IPR2025-01312 has been instituted, defendants should closely monitor its progress. The institution decision (IPR2025-01312, Paper 9, issued February 27, 2026) is available on the USPTO PTAB E2E system.
• Anticipated milestones include an oral hearing (typically 6-9 months post-institution) and the Final Written Decision (FWD), which is due by approximately 2027-02-27. The outcome of the FWD will be critical in determining the validity of claims 1-6, 9-13, and 15-20.
• If your infringement theories are based on claims 1-6, 9-13, or 15-20, immediately assess the strength of those theories in light of the prior art cited in the institution decision. Consider potential alternatives relying on the unchallenged claims (7, 8, 14, 21-25), if applicable, while recognizing these claims remain untested by this IPR.

Citations:
IPR2025-01312, Paper 9, Decision to Institute Inter Partes Review, dated February 27, 2026.

Inventors

• Kozo Masuda (Hitachi Ltd)
• Ikuya Arai (Hitachi Ltd)
• Masaaki Miyano (Hitachi Ltd)

All inventors were employed by Hitachi Ltd, the original assignee, at the time of filing. There are no unusual patterns indicating immediate departure of inventors.

Original assignee

Hitachi Ltd.
Hitachi Ltd. is a major Japanese multinational conglomerate producing a wide range of products including electronics, machinery, and industrial solutions. They would have shipped numerous products embodying video processing technologies as claimed in the patent.
Current Status: Operating.

Assignment timeline

• 2006-12-20 (executed) / recorded 2007-02-01 — Reel 019256/0313
  • Conveyance: Assignment
  • Assignor: MIYANO, MASAAKI; ARAI, IKUYA; MASUDA, KOZO
  • Assignee: HITACHI, LTD.
  • Correspondent: ANTONELLI, TERRY, STOUT & KRAUS, LLP, 1300 NORTH 17TH STREET, SUITE 1800, ARLINGTON, VA 22209.
  • Context: Assignment from inventors to original corporate assignee.
• 2014-08-25 (executed) / recorded 2014-09-08 — Reel 032997/0229
  • Conveyance: Assignment
  • Assignor: HITACHI, LTD.
  • Assignee: HITACHI MAXELL, LTD.
  • Correspondent: ANTONELLI, TERRY, STOUT & KRAUS, LLP, 1300 NORTH 17TH STREET, SUITE 1800, ARLINGTON, VA 22209. (This correspondent recurs in this chain.)
  • Context: Internal corporate transfer between related operating entities.
• 2018-01-19 (executed) / recorded 2018-01-25 — Reel 041838/0566
  • Conveyance: Assignment
  • Assignor: HITACHI MAXELL, LTD.
  • Assignee: MAXELL, LTD.
  • Correspondent: KOBAYASHI, TAKASHI, C/O ANTONELLI, TERRY, STOUT & KRAUS, LLP, 1300 NORTH 17TH STREET, SUITE 1800, ARLINGTON, VA 22209. (This firm recurs in this chain.)
  • Context: Corporate name change/reorganization (Hitachi Maxell, Ltd. changed its name to Maxell, Ltd. in 2017).
• 2021-11-25 (executed) / recorded 2021-11-29 — Reel 054817/0001
  • Conveyance: Merger
  • Assignor: MAXELL, LTD.
  • Assignee: MAXELL HOLDINGS, LTD.
  • Correspondent: HAHN, KENT, MAXELL, LTD., 3333 PEACHTREE ROAD NE, SUITE 400, ATLANTA, GA 30326.
  • Context: Corporate merger where Maxell, Ltd. merged into Maxell Holdings, Ltd.
• 2021-12-01 (executed) / recorded 2021-12-03 — Reel 054823/0001
  • Conveyance: Change of Name
  • Assignor: MAXELL HOLDINGS, LTD.
  • Assignee: MAXELL, LTD.
  • Correspondent: HAHN, KENT, MAXELL, LTD., 3333 PEACHTREE ROAD NE, SUITE 400, ATLANTA, GA 30326. (This correspondent recurs in this chain.)
  • Context: Corporate name change where Maxell Holdings, Ltd. changed its name to Maxell, Ltd.

Timeline diagram

timeline
    title Ownership of US 7952645
    2006 : Inventors assign to Hitachi
    2011 : Issued
    2014 : Assigned to Hitachi Maxell
    2018 : Assigned to Maxell Ltd
    2021 : Maxell merged into Maxell Holdings
         : Maxell Holdings changes name to Maxell

NPE / troll-pattern signals

1. Shell-entity transfer — Not present. The assignees in the chain (Hitachi Ltd, Hitachi Maxell Ltd, Maxell Ltd, Maxell Holdings Ltd) are all known operating companies.
2. Known asserter in the chain — Not present. None of the assignees (Hitachi Ltd, Hitachi Maxell Ltd, Maxell Ltd, Maxell Holdings Ltd) are listed on public NPE lists.
3. Repeat correspondent across the chain — Present. Antonelli, Terry, Stout & Kraus, LLP appears on the first two assignments (Reel 019256/0313, Reel 032997/0229) and the firm (c/o Kobayashi, Takashi) on the third (Reel 041838/0566). Kent Hahn appears on the fourth and fifth entries (Reel 054817/0001, Reel 054823/0001). This consistency suggests corporate management of the portfolio rather than disjointed shell entity transfers.
4. Cascading transfers — Unclear. While there were two transfers in quick succession in 2021 (Nov 29 and Dec 3), these were explicitly recorded as a Merger and a Change of Name (Reel 054817/0001, Reel 054823/0001), indicating an internal corporate reorganization rather than a "cascading transfer" to multiple distinct shell entities.
5. Pre-litigation transfer — Not present. There is no indication of transfers immediately preceding litigation. The patent shows litigation activity starting in 2021-11, after the initial corporate assignments and preceding the specific merger/name change events.
6. Bankruptcy fire-sale — Not present. There is no evidence of any assignee in the chain undergoing bankruptcy proceedings leading to a patent sale.
7. Privateering — Not present. There is no evidence from SEC filings or other sources indicating this patent was transferred to an NPE to assert on behalf of an operating company.
8. Defensive aggregator (anti-NPE) — Not present. The chain does not terminate at a known defensive aggregator.

Verdict

Operating-company assertion
The assignment chain demonstrates internal corporate transfers, mergers, and name changes involving well-known operating companies: Hitachi, Hitachi Maxell, and Maxell, Ltd. The current assignee, Maxell, Ltd., is a manufacturer and developer of consumer and industrial products, suggesting that any assertion would likely be by an operating company against direct competitors. The consistent correspondent law firm in the initial transfers also supports this.
USPTO Assignment Center Search for US7952645

The following are the most relevant prior art references for US patent 7952645, identified by examining the patent's own background section and its cited prior art. Each reference includes its full citation, publication/filing dates, a brief description, and an analysis of which claims of US7952645 it potentially anticipates under 35 U.S.C. § 102.

Most Relevant Prior Art for US7952645

1. JP2002132225A - Video signal processing method and apparatus

• Full Citation: JP2002132225A (Google Patents link for JP2002132225A:)
• Publication Date: 2002-05-10
• Filing Date: 2000-10-27
• Brief Description: This patent describes a multimedia computer system that converts RGB signals to luminance and color-difference signals, extracts characteristic points from the luminance signal (e.g., minimum, maximum, average levels, histogram) for each frame, and then corrects both the luminance and color-difference signals for display.
• Potential Anticipation for US7952645 Claims:
  • Claim 1: This reference directly anticipates the core components of Claim 1 relating to converting an RGB input signal to luminance and color-difference signals, extracting characteristic data from the luminance signal, and correcting (modulating) the luminance and color-difference signals based on these characteristics to enhance picture quality. While the specific "interrupt signal" handling and the detailed selector functionality described in Claim 1 might be distinguishing, the fundamental video processing steps are disclosed.

2. JP2005026814A - Picture quality correction system

• Full Citation: JP2005026814A (Google Patents link for JP2005026814A:)
• Publication Date: 2005-01-27
• Filing Date: 2003-07-07
• Brief Description: This patent discloses a side panel detection circuit that detects "side panels" (analogous to wallpaper portions or no-picture areas) in a video signal and conducts picture quality correction based on the detection result and the video luminance level.
• Potential Anticipation for US7952645 Claims:
  • Claim 11: This reference directly anticipates the detection of "pattern portions" (e.g., wallpaper portions or side panels) within an input video signal and the control of video signal correction based on this detection, particularly for preventing unwanted changes in these non-content areas.
  • Claim 12: It also broadly anticipates the detection of "no-picture area portions" (e.g., single-color side panels) and changing the area of picture quality enhancement processing to exclude these portions, thereby preventing their luminance and color information from improperly influencing corrections for the actual content.

3. US6744474B1 - Image processing system

• Full Citation: US6744474B1 - Image processing system (Google Patents link for US6744474B1:)
• Publication Date: 2004-06-01
• Filing Date: 2001-08-27
• Brief Description: This patent describes an image processing system that generates a histogram of image data, performs image processing on the data based on the histogram, and controls a display device. It also aims to improve visibility in bright ambient light conditions by adjusting display luminance and contrast using image processing.
• Potential Anticipation for US7952645 Claims:
  • Claim 1: This patent anticipates the creation of a histogram (characteristic data), the use of this histogram to perform image processing (determining correction data), and the modulation of image characteristics (luminance/contrast) for display.
  • Claim 9: The mention of improving visibility in bright ambient light by adjusting display luminance and contrast suggests anticipation of the general concept of ambient light-adaptive correction, though specific photo sensor details and RGB gain adjustment would require further analysis.

4. US7088383B2 - Image display device and image display method

• Full Citation: US7088383B2 - Image display device and image display method (Google Patents link for US7088383B2:)
• Publication Date: 2006-08-08
• Filing Date: 2004-03-12
• Brief Description: This patent describes an image display device and method that detects characteristic values of an input image and varies display characteristics (e.g., gradation, luminance, contrast) based on these values. It specifically includes improving outdoor visibility by using an external light sensor.
• Potential Anticipation for US7952645 Claims:
  • Claim 1: It anticipates detecting characteristic values of an input image and dynamically adjusting display characteristics such as gradation, luminance, and contrast, aligning with the core picture quality enhancement aspects of Claim 1.
  • Claim 9 & 10: The explicit mention of using an external light sensor to improve outdoor visibility and adjusting image characteristics based on external light strongly anticipates the use of a photo sensor for ambient light correction, as detailed in Claim 9. Deeper analysis would be needed to determine if it specifically discloses RGB detection and ratio calculation as in Claim 10.

5. US20050168603A1 - Video signal processing circuit and method

• Full Citation: US20050168603A1 - Video signal processing circuit and method (Google Patents link for US20050168603A1:)
• Publication Date: 2005-08-04
• Filing Date: 2004-01-21
• Brief Description: This patent describes a video signal processing circuit and method that employs a histogram generator to obtain a histogram of an input video signal. It then performs gamma correction and adjusts black/white levels according to the generated histogram to achieve good gradation characteristics.
• Potential Anticipation for US7952645 Claims:
  • Claim 1: This reference directly anticipates the generation of a histogram (characteristic data) from an input video signal and the use of this histogram to perform image correction, such as gamma correction and black/white level adjustment, which are forms of modulating the luminance signal for picture quality enhancement as described in US7952645.The analysis of the most relevant prior art for US patent 7952645 is provided below, focusing on references that either appear in the patent's own background discussion or broadly cover its independent claims. The specific details for each cited patent, including publication/filing dates and brief descriptions, are primarily drawn from publicly available patent databases such as Google Patents.

Most Relevant Prior Art for US7952645

1. JP2002132225A - Video signal processing method and apparatus

• Full Citation: JP2002132225A (Video signal processing method and apparatus)
• Publication Date: 2002-05-10
• Filing Date: 2000-10-27
• Brief Description: This patent describes a multimedia computer system that converts an input RGB signal into a luminance signal and color-difference signals. It extracts characteristic points in the luminance signal for each frame, corrects the luminance and color-difference signals, and then displays the resulting image. [cite: The full patent text of US7952645 discusses this prior art in its 'BACKGROUND' section.]
• Potential Anticipation for US7952645 Claims:
  • Claim 1: This reference directly anticipates the core elements of Claim 1, including the conversion of an RGB input video signal to luminance and color-difference signals, the extraction of characteristic data from the luminance signal, and the modulation (correction) of these signals to enhance picture quality. While the specific mechanism of an "interrupt signal" for CPU interaction and the detailed selector functionality described in Claim 1 may present distinctions, the fundamental video processing steps are disclosed.

2. JP2005026814A - Picture quality correction system

• Full Citation: JP2005026814A (Picture quality correction system)
• Publication Date: 2005-01-27
• Filing Date: 2003-07-07
• Brief Description: This patent discloses a side panel detection circuit that detects side panels (which are comparable to pattern portions or no-picture areas) in a video signal. It then conducts picture quality correction based on the detection of these side panels and the video luminance level. [cite: The full patent text of US7952645 discusses this prior art in its 'BACKGROUND' section.]
• Potential Anticipation for US7952645 Claims:
  • Claim 11: This reference directly anticipates the detection of "pattern portions" (such as wallpaper portions or side panels) within an input video signal and the subsequent control of the video signal correction based on this detection. The underlying principle of preventing undesired correction of static or non-content areas is present.
  • Claim 12: It broadly anticipates the detection of "no-picture area portions" (e.g., single-color side panels or black bars) and the adjustment of the picture quality enhancement processing area to exclude these portions. This prevents the luminance and color information from these non-content areas from interfering with the accurate correction of the main video content.

3. US6744474B1 - Image processing system

• Full Citation: US6744474B1 (Image processing system)
• Publication Date: 2004-06-01
• Filing Date: 2001-08-27
• Brief Description: This patent describes an image processing system comprising a histogram creation circuit for generating a histogram of image data. It then performs image processing on the image data based on this histogram and controls a display device. The invention also aims to improve visibility in bright ambient light by adjusting display luminance and contrast through image processing.
• Potential Anticipation for US7952645 Claims:
  • Claim 1: This patent anticipates the creation of a histogram (a form of characteristic data), the use of this histogram to perform image processing (which involves determining correction data and modulation), and the subsequent control of a display.
  • Claim 9: The explicit mention of improving visibility in bright ambient light by adjusting display luminance and contrast through image processing suggests anticipation of the general concept of ambient light-adaptive correction. However, the specific integration of a photo sensor and RGB gain adjustment as detailed in Claim 9 would require a more in-depth comparison.

4. US7088383B2 - Image display device and image display method

• Full Citation: US7088383B2 (Image display device and image display method)
• Publication Date: 2006-08-08
• Filing Date: 2004-03-12
• Brief Description: This patent describes an image display device and method capable of reproducing high-quality images. It detects characteristic values of an input image and varies the image display characteristics, such as gradation, luminance, and contrast, based on these values. It also explicitly mentions improving visibility outdoors by utilizing an external light sensor.
• Potential Anticipation for US7952645 Claims:
  • Claim 1: This patent anticipates the detection of characteristic values from an input image and the dynamic adjustment of display characteristics like gradation, luminance, and contrast, which aligns with the core picture quality enhancement features of Claim 1.
  • Claim 9 & 10: The explicit disclosure of improving outdoor visibility using an external light sensor and adjusting image characteristics based on this external light strongly anticipates the use of a photo sensor for ambient light correction as outlined in Claim 9. Further examination would be needed to determine if the patent specifically details RGB detection and ratio calculation as in Claim 10.

5. US20050168603A1 - Video signal processing circuit and method

• Full Citation: US20050168603A1 (Video signal processing circuit and method)
• Publication Date: 2005-08-04
• Filing Date: 2004-01-21
• Brief Description: This patent details a video signal processing circuit and method designed to achieve good gradation characteristics. It utilizes a histogram generator to obtain a histogram of an input video signal and then employs a gamma correction circuit to perform gamma correction, along with adjusting black/white levels, based on the generated histogram.
• Potential Anticipation for US7952645 Claims:
  • Claim 1: This reference directly anticipates the generation of a histogram (a form of characteristic data) from an input video signal and the subsequent use of this histogram to perform image correction, specifically through gamma correction and black/white level adjustment. These are direct implementations of modulating the luminance signal for picture quality enhancement, as described in US7952645.

Obviousness Analysis of US Patent 7952645 under 35 U.S.C. § 103

This analysis identifies combinations of prior art references, explicitly mentioned in US patent 7952645, that would render the independent claims obvious to a person having ordinary skill in the art (POSITA). The motivation for combining these references is also discussed, often rooted in addressing known problems or achieving predictable results within the field of video processing for mobile terminals.

Prior Art References

The patent US7952645 itself acknowledges the following prior art:

• JP-A-2002-132225: Discloses "a multimedia computer system which converts an input RGB signal to a luminance signal and a color-difference signal, extracts a characteristic point in the luminance signal every frame, corrects the luminance signal and the color-difference signal, and conducts display".
• JP-A-2005-26814: Discloses "a side panel detection circuit which detects a side panel and conduct picture quality according to a result of the side panel detection and a result of video luminance level detection".

Obviousness Arguments for Independent Claims

Claim 1: Video Processing Apparatus with Context-Dependent Selector

Elements of Claim 1:
Claim 1 describes a video processing apparatus including:

1. An RGB-YUV converter.
2. A characteristic point detector that determines characteristics (minimum, average, maximum levels, and histogram) of the luminance signal, hue, and saturation.
3. A CPU that determines correction data based on these characteristics upon detecting an interrupt signal.
4. A modulator that corrects the luminance signal, hue, and saturation based on the correction data.
5. An HS-color-difference converter and a YUV-RGB converter.
6. A selector for choosing between the original or corrected video signal based on battery residual quantity, open/close state of the mobile terminal, or content type.

Combination of Prior Art:
A person of ordinary skill in the art would find Claim 1 obvious in view of JP-A-2002-132225 in combination with general knowledge of power management and user interface design in mobile terminals.

Rationale for Obviousness:
JP-A-2002-132225 clearly teaches the core video processing steps: converting RGB to YUV signals, extracting characteristic points from the luminance signal (implying the ability to analyze and derive correction data), correcting luminance and color-difference signals, and displaying the result. While JP-A-2002-132225 specifically mentions luminance characteristic points, a POSITA would find it obvious to extend the characteristic detection to include hue (H) and saturation (S) because these are directly derivable from the color-difference signals (R-Y and B-Y) that are already being processed. The motivation for this extension would be to achieve more comprehensive and aesthetically pleasing picture quality enhancement, addressing aspects of color perception in addition to brightness.

The inclusion of a selector (158) in a mobile terminal (as stated in the patent's description that the invention can be applied to portable telephones) to switch between the original and enhanced video signals based on factors like battery residual quantity, device open/close state, or content type, would be a well-known engineering design choice for power management and user experience optimization in portable electronic devices. For example, the patent itself mentions selecting the through signal in a waiting state to reduce power consumption. A POSITA would be motivated to combine the video enhancement techniques of JP-A-2002-132225 with such a selector to conserve battery life in a mobile device or to provide an optimized display experience based on usage context, leading to a predictable improvement in convenience for a battery-operated apparatus.

Claim 9: Mobile Terminal with Ambient Light Correction

Elements of Claim 9:
Claim 9 describes a mobile terminal incorporating the video processing apparatus of Claim 1, further including:

1. A photo sensor that detects ambient illuminance.
2. A CPU that determines additional correction data based on the detected ambient illuminance.
3. An RGB gain adjuster that applies the additional correction data to the video signal.

Combination of Prior Art:
Claim 9 would be obvious in view of the combination of JP-A-2002-132225 (as a basis for the video processing apparatus from Claim 1) and general knowledge in the art regarding ambient light sensors in displays, particularly in mobile devices.

Rationale for Obviousness:
Given a mobile terminal with video processing capabilities for enhancing picture quality (made obvious by JP-A-2002-132225 and common mobile device practices as discussed for Claim 1), a POSITA would recognize the problem of diminished display visibility in varying ambient light conditions, especially bright outdoor environments (as the patent notes, "In a bright environment such as outdoors in a clear day... the gradation on the low luminance side, i.e., the black side of the displayed image becomes hard to discriminate"). The use of photo sensors to detect ambient light and automatically adjust display parameters (like brightness or contrast) to improve readability and user comfort is a well-established technique in display technology. Integrating a photo sensor (21, as shown in FIG. 19 of the patent) into the mobile terminal and having the CPU (7) use its output to generate additional correction data (e.g., to emphasize black side gradations, as illustrated in FIGS. 23B/D) to be applied by an RGB gain adjuster (1510) would be a logical and predictable step for a POSITA. The motivation would be to address the known challenge of outdoor visibility in mobile displays, resulting in an image that is easier to view in bright surroundings.

Claim 10: Mobile Terminal with RGB Ambient Color Correction

Elements of Claim 10:
Claim 10 specifies the mobile terminal of Claim 9, where:

1. The photo sensor includes independent RGB detection elements.
2. The CPU calculates ratios among the RGB output colors of the photo sensor.
3. The RGB gain adjuster lowers the correction value for the color component that is much in quantity in the ambient light.

Combination of Prior Art:
Claim 10 would be obvious in view of the combination of Claim 9 (which includes ambient illuminance correction) and general knowledge in the art regarding advanced ambient light sensing for color temperature compensation.

Rationale for Obviousness:
Building upon the use of ambient illuminance for correction (as in Claim 9), a POSITA would further understand that the color temperature of ambient light also significantly influences perceived display quality. The patent highlights this problem, stating, "if the color of sunlight is reddish as in the evening sun, there is a problem that the color of the display image is made reddish under the influence of the sunlight". Employing a photo sensor with separate RGB detection elements to measure not just intensity but also the color components of ambient light is a known technique used in various fields, such as camera white balance or adaptive display technologies, to achieve more accurate color reproduction. A POSITA would be motivated to combine the ambient illuminance correction of Claim 9 with a more sophisticated ambient color temperature compensation to maintain color fidelity under diverse lighting conditions. Calculating ratios of the RGB components from such a sensor and intelligently adjusting the display's RGB gain to counteract the dominant ambient color (e.g., decreasing the R correction if ambient light has a strong red component) is a predictable and logical extension for improving overall display quality and user experience.

Claim 11: Mobile Terminal with Pattern Portion Detection and Correction Suppression

Elements of Claim 11:
Claim 11 describes a mobile terminal including a video processing apparatus where:

1. A detector detects whether "pattern portions" (e.g., wallpaper portions or patterned areas) are contained in the video signal.
2. If pattern portions are detected, the corrector (modulator) is controlled so as not to correct the video signal or to weaken the correction.

Combination of Prior Art:
Claim 11 would be obvious in view of JP-A-2002-132225 (for the general video processing) in combination with JP-A-2005-26814.

Rationale for Obviousness:
JP-A-2005-26814 explicitly discloses "a side panel detection circuit which detects a side panel and conduct picture quality according to a result of the side panel detection and a result of video luminance level detection". "Side panels" are functionally equivalent to "pattern portions" or "wallpaper portions" as described in US7952645, often inserted to fill empty display areas when content has a different aspect ratio. The patent identifies a clear problem: "If such a video signal is subjected to picture quality correction, then luminance and colors of the wallpaper portions are changed according to the contents of the video signal and consequently there is a risk that the image becomes rather hard to watch and the convenience in user's use becomes worse".

A POSITA, aware of the video enhancement techniques of JP-A-2002-132225 (or Claim 1's general video processing) and the side panel detection capability of JP-A-2005-26814, would be motivated to combine these teachings to prevent undesirable visual artifacts. The motivation would be to address the specific problem of static pattern portions (like side panels) flickering or changing luminance/color when global picture quality correction is applied, which degrades the viewing experience. JP-A-2005-26814 already suggests adapting "picture quality according to a result of the side panel detection". Therefore, controlling the corrector (modulator 152 in US7952645, as shown in FIG. 27) to stop or weaken correction for these detected pattern portions (as implemented by pattern portion detector 1511) would be a direct and predictable solution to maintain the stability and visual comfort of these static background elements.

Claim 12: Mobile Terminal with No-Picture Area Detection and Exclusion from Characteristic Detection

Elements of Claim 12:
Claim 12 describes a mobile terminal including a video processing apparatus where:

1. A detector detects whether "no-picture area portions" (e.g., single color black bars) are contained in the video signal.
2. If no-picture area portions are detected, the area where characteristic data is detected is controlled to exclude the no-picture areas.

Combination of Prior Art:
Claim 12 would be obvious in view of JP-A-2002-132225 (for the general video processing including characteristic detection) in combination with JP-A-2005-26814 (for area detection capabilities) and the problem identified in US7952645.

Rationale for Obviousness:
The patent explicitly states the problem addressed by this claim: "if black no-picture areas are added to the left and right sides of the contents having the aspect ratio of 4:3, luminance and color information of the black no-picture areas are confused. This results in a problem that average values of luminance and color of the 4:3 contents themselves cannot be calculated accurately".

Building on a video processing system that performs characteristic point detection for correction (as taught by JP-A-2002-132225, which extracts "a characteristic point in the luminance signal every frame"), and having knowledge of area detection (such as "side panel detection" from JP-A-2005-26814), a POSITA would be motivated to refine the characteristic detection process. The motivation is to ensure that the calculated luminance and color characteristics (e.g., histograms, average values) accurately represent the actual content of the video signal, rather than being skewed by static, non-informative "no-picture areas" like black bars. Detecting these single-color no-picture areas (similar to how JP-A-2005-26814 detects side panels) and then logically excluding them from the characteristic point detection area (as implemented by the characteristic point detection area controller 1512, shown in FIG. 37 and FIG. 38) is a straightforward and predictable engineering solution. This approach directly addresses the problem of obtaining accurate characteristic data for the main content, leading to more appropriate and effective picture quality corrections.