JPEG Chroma Low-Pass Filter for Blocking Artifact Removal

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

JPEG compression introduces artifacts such as blocking artifacts in decompressed images due to its lossy nature and down-sampling of chroma components.

Innovation Solution

Applying a low-pass filter to the de-quantized and upsampled Chroma data in JPEG decompressed images to reduce or eliminate blocking artifacts, thereby maintaining image quality.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of substance

If JPEG compression is applied to reduce image data size, then compression efficiency is improved, but blocking artifacts are introduced into the decompressed image

Engineering Contradiction:

Improveimage data sizeVSAvoidblocking artifacts

Core Design Contradiction:

Loss of substanceVSObject-affected harmful factors

Solution Approach 1:

The patent applies a low-pass filter to the decompressed Chroma channel to convert the harmful blocking artifacts into beneficial smooth transitions. The filter removes high-frequency components that cause visible blocking while preserving the overall color information, effectively transforming the artifact problem into a solution that maintains both compression efficiency and visual quality

Inventive Principle:

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

2Loss of substance

If Chroma channel is down-sampled to reduce data, then compression ratio is improved, but color accuracy deteriorates

Engineering Contradiction:

ImproveChroma data volumeVSAvoidcolor accuracy

Core Design Contradiction:

Loss of substanceVSManufacturing precision

Solution Approach 1:

The patent applies different processing to different channels: the Luma channel is preserved with high fidelity while the Chroma channel receives low-pass filtering after decompression. This local quality approach maintains brightness accuracy where it matters most while applying smoothing to color information where human perception is less sensitive, thereby preserving overall color accuracy despite down-sampling

Inventive Principle:

Principle #3Local quality

3Productivity

If DCT coefficients are quantized to eliminate high frequencies, then compression efficiency is improved, but image detail is lost

Engineering Contradiction:

Improvecompression efficiencyVSAvoidimage detail

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The patent changes the processing parameter of the Chroma channel by applying a low-pass filter after decompression rather than relying solely on DCT quantization. This additional filtering step smoothly transitions the quantized coefficients, eliminating blocking artifacts while preserving the compression efficiency achieved through quantization of the most important Luma details

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS12309427B2Image compression

Publication Date: 2025.05.20 CONTRAST INC

AI summary

The invention provides methods that improve image compression and/or quality within the JPEG process by using a low-pass filter to remove high frequency components from image data, which removes blocking artifacts. Preferred embodiments apply the low-pass filter to the Chroma components after decompression prior to conversion into RGB color space.