Film Grain Parameter Estimation for Lower-Bitrate Video Coding
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Solution Overview
Problem
Existing video compression methods suppress film grain, a desirable feature for enhancing video quality, without the possibility of reconstructing it, leading to loss of visual appeal and increased bitrate.
Innovation Solution
A method for estimating film grain parameters using scaling factors based on original video content statistics, allowing for precise film grain synthesis at the decoder side, reducing bitrate and improving visual quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If film grain is preserved in the original video content, then visual quality and natural appearance are improved, but compression efficiency deteriorates and bitrate increases
Solution Approach 1:
The patent extracts film grain as a separate component from the video content. The encoder identifies and separates film grain characteristics (such as noise patterns and texture) from the main video signal, allowing the grain to be removed before compression. This extraction enables the compressed video to be reconstructed with synthesized film grain, maintaining visual quality while improving compression efficiency.
Solution Approach 2:
The patent applies preliminary film grain synthesis during the encoding process. By pre-generating film grain parameters and characteristics before compression, the system can efficiently compress the video content without the grain, then reconstruct the grain during decoding. This preliminary action separates the grain preservation task from the compression task, resolving the contradiction between visual quality and compression efficiency.
2Productivity
If film grain is removed prior to compression, then compression efficiency is improved, but the original film grain appearance is lost
Solution Approach 1:
The patent creates a copy or model of the film grain characteristics during encoding. By analyzing the original video content and extracting grain parameters (such as spectral characteristics, intensity, and spatial distribution), the system generates a compact representation of the grain. This copy is transmitted alongside the compressed video, enabling accurate grain reconstruction at the decoder without losing the original appearance.
Solution Approach 2:
The patent transforms film grain from a spatial-domain signal into frequency-domain parameters. By converting grain characteristics into spectral parameters (such as power spectral density, cutoff frequencies, and statistical properties), the system efficiently encodes the grain information with minimal bitrate. These parameter changes enable compact representation that can be used for high-fidelity grain synthesis during decoding.
3Ease of manufacture
If manual film grain parameters are used, then implementation simplicity is maintained, but parameter precision and adaptability deteriorate
Solution Approach 1:
The patent implements automatic film grain parameter estimation that performs self-analysis of the video content. The encoder automatically detects and extracts film grain characteristics from the input video without requiring manual intervention. This self-service approach analyzes statistical properties, spectral characteristics, and spatial patterns of the grain, generating precise parameters tailored to each specific video content, thereby eliminating the need for manual parameter selection while maintaining implementation simplicity.
Data Source
AI summary
At least a method and an apparatus are presented for efficiently processing film grain while encoding or decoding video. For example, the method comprises estimating film grain parameters for a plurality of image blocks in an image with film grain, wherein the film grain parameters comprise at least one scaling factor. The estimating further comprises obtaining a plurality of film grain blocks, a film grain block being representative of a film grain estimate in an image block; obtaining a plurality of filtered blocks, a filtered block being representative of an image block without film grain; and determining at least one scaling factor for the plurality of images blocks in the image wherein the at least one scaling factor is adapted to statistics based on the plurality of film grain blocks and on the plurality of filtered blocks.