Subtitle Color Gamut Adjustment for Video Superimposition
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Solution Overview
Problem
In existing video broadcasting systems, there is no clear method to ensure high image quality when combining video data with subtitle data, particularly when the color gamut and dynamic range of the two differ, leading to potential quality issues during superposition.
Innovation Solution
A reception device that adjusts the color gamut and luminance of subtitle data to match the video data, using identification information from both streams to ensure compatibility and superimpose them effectively, while also incorporating a video level adjustment unit to prevent subtitle obstruction by high luminance backgrounds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If subtitle data with different color gamut is superimposed on video data without adjustment, then processing is simple, but image quality deteriorates
Solution Approach 1:
The patent applies preliminary action by performing color gamut adjustment on subtitle data before superposition. The adjustment unit converts subtitle color gamut to match video color gamut in advance, using identification information to determine the target color gamut. This prevents quality deterioration while maintaining relatively simple processing by establishing a one-time conversion rule based on metadata.
Solution Approach 2:
The patent applies parameter changes by modifying the color gamut parameters of subtitle data. The adjustment unit changes the color space parameters (e.g., from sRGB to BT.2020) based on identification information from the video stream, enabling accurate color representation without complex real-time processing during superposition.
2Manufacturing precision
If subtitle data with different dynamic range is superimposed on video data without adjustment, then processing is simple, but image quality deteriorates
Solution Approach 1:
The patent applies preliminary action by performing dynamic range adjustment on subtitle data before superposition. The adjustment unit converts SDR subtitle data to HDR in advance using identification information to determine the target dynamic range, preventing luminance mismatch and quality deterioration while keeping processing manageable through pre-established conversion rules.
Solution Approach 2:
The patent applies parameter changes by modifying the dynamic range parameters of subtitle data. The adjustment unit changes luminance range parameters (e.g., from SDR 0-255 to HDR 0-1000 nits) based on identification information from the video stream, enabling accurate luminance representation without complex real-time processing during superposition.
3Manufacturing precision
If high luminance background video is displayed, then video quality is high, but subtitle readability deteriorates
Solution Approach 1:
The patent applies local quality by adjusting the luminance of video data specifically in the subtitle display region. The adjustment unit detects high luminance areas within the subtitle region and applies localized luminance reduction only where subtitles will be displayed, preserving overall video quality while improving subtitle readability in critical areas.
Solution Approach 2:
The patent applies the intermediary principle by introducing a luminance adjustment mechanism as a mediator between the high luminance video background and the subtitle data. The adjustment unit acts as an intermediary that modifies video luminance in the subtitle region to create optimal viewing conditions, balancing video quality and subtitle readability.
Data Source
AI summary
The technology is directed to keeping high image quality when a subtitle is superimposed on a video. A reception device includes circuitry configured to receive a video stream and a subtitle stream. The circuitry processes the video stream to obtain video data of a video. The circuitry processes the subtitle stream to obtain subtitle bitmap data of a subtitle bitmap image. The circuitry adjusts a color gamut of the subtitle bitmap data to a color gamut of the video data. The color gamut of the subtitle bitmap data is adjusted based on color gamut identification information of the subtitle bitmap data and color gamut identification information of the video data. The circuitry further superimposes, on the video, the color gamut adjusted subtitle bitmap image.