Color Space Conversion Pipeline with Invalid Pixel Handling

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Solution Overview

Problem

Color space conversion, particularly from YCbCr to RGB, can result in invalid pixel values in the RGB color space, leading to inaccurate representation and visual discrepancies in displayed images.

Innovation Solution

A video processing system that includes a video pipe for converting pixels from a first color space (e.g., YCbCr) to a second color space (e.g., RGB), with a blend unit that handles invalid values by converting them back to the original color space, ensuring accurate representation and display on various devices.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If color space conversion is performed from YCbCr to RGB, then the video processing system can operate in a different color space for blending operations, but invalid pixel values are generated that cannot be accurately represented in the RGB color space

Engineering Contradiction:

Improvecolor space flexibilityVSAvoidcolor value accuracy

Core Design Contradiction:

Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The system performs color space conversion from YCbCr to RGB in advance before blending operations, allowing the blender unit to work in RGB color space. However, when invalid values are detected after blending, the system converts them back to YCbCr space to maintain accuracy, thus resolving the contradiction between operational flexibility and measurement precision.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent introduces an intermediary conversion process that temporarily stores invalid RGB values and converts them back to YCbCr space. This intermediary mechanism allows the system to benefit from RGB operations while maintaining YCbCr accuracy for colors that cannot be represented in RGB, thus resolving the contradiction between color space flexibility and color value accuracy.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Ease of manufacture

If color values are converted from YCbCr to RGB, then blending operations can be performed in RGB color space, but colors from YCbCr space with wider gamut cannot be adequately represented in RGB space

Engineering Contradiction:

Improveblending operation compatibilityVSAvoidcolor information loss

Core Design Contradiction:

Ease of manufactureVSLoss of information

Solution Approach 1:

The system implements a feedback mechanism that detects invalid RGB values resulting from YCbCr to RGB conversion. When invalid values are detected, the system converts them back to YCbCr space, providing feedback that preserves color information that would otherwise be lost due to RGB's limited gamut compared to YCbCr.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent changes the color space parameter dynamically based on the validity of converted values. When RGB conversion produces valid values, operations proceed in RGB space for ease of blending. When invalid values are detected, the system switches back to YCbCr parameter space to preserve color information, thus resolving the contradiction between operational ease and information preservation.

Inventive Principle:

Principle #35Parameter changes

3Productivity

If invalid RGB values are used in blending operations, then processing can continue without interruption, but visual discrepancies occur in the displayed images

Engineering Contradiction:

Improveprocessing continuityVSAvoidvisual accuracy

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent converts the harmful effect of invalid RGB values into a beneficial process by detecting these invalid values and automatically converting them back to YCbCr space. This transformation turns the harmful invalid values into valid YCbCr values, maintaining both processing continuity and visual accuracy, thus resolving the contradiction between productivity and reliability.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The system replaces the mechanical continuation of processing with a corrective conversion mechanism. Instead of simply continuing processing with invalid values, the system substitutes a conversion step that transforms invalid RGB values into valid YCbCr values, ensuring both continuous processing and accurate visual output.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Data Source

PatentUS8773457B2Color space conversion

Publication Date: 2014.07.08 APPLE INC

AI summary

A display pipe may include a video pipe outputting pixels of a video stream in a first color space, e.g. YCbCr color space. The display pipe may also include a first color space converter to convert the output pixels to a second color space, e.g. to RGB color space, producing a conversion output in which some of the converted output pixels have values that are invalid pixel values in the second color space. The display pipe may also include a blend unit that performs blending operations in the second color space on the converted output pixels to produce a blended conversion output that includes blended pixels in the second color space. A second color space converter in the display pipe may convert the blended pixels from the second color space to the first color space, and correctly display the converted blended pixels on a display screen.