Two-Stage Image Decoding for Large Images
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Solution Overview
Problem
Existing image decoding methods for portable devices are either excessively time-consuming when decoding non-displayed portions of large images or compromise image quality by generating thumbnail images.
Innovation Solution
A method that decodes a minimum code unit (MCU) of a compressed image bit stream in two stages: a first stage generates a temporary decoding result, and if the MCU requires display, a second stage produces display data, optimizing processing for only the necessary image portions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the entire image is fully decoded for display, then the selected portion can be displayed with full image quality, but the processing time becomes excessively long
Solution Approach 1:
The patent divides the image into multiple minimum code units (MCUs), each containing multiple 8x8 blocks. The decoding process is segmented into two stages: a first stage that decodes all MCUs to generate temporary results, and a second stage that only processes MCUs required for display. This segmentation allows the system to avoid fully decoding the entire large image while maintaining quality for the displayed portion.
Solution Approach 2:
The patent performs partial decoding by executing the first decoding stage for all MCUs but only executing the second decoding stage for MCUs that contain pixels within the selected display region. This partial action approach decodes only the necessary portions of the image at full quality, avoiding the excessive processing time of decoding the entire image.
2Loss of time
If a thumbnail image is generated and enlarged for display, then the processing time is reduced, but the image quality deteriorates
Solution Approach 1:
The patent segments the decoding process into two distinct stages. The first stage decodes all MCUs to generate temporary results that contain essential information. The second stage selectively processes only those MCUs that correspond to the selected display region, applying full decoding to maintain image quality while avoiding processing of non-displayed areas.
Solution Approach 2:
The first decoding stage serves as a preliminary action that prepares temporary results for all MCUs without completing the full decoding process. This preliminary decoding provides sufficient information to determine which MCUs are needed for the selected region, enabling the system to skip unnecessary full decoding operations and thus reduce processing time while maintaining quality for displayed portions.
3Adaptability or versatility
If non-displayed portions of the image are decoded, then the complete image is available for future operations, but the processing time increases unnecessarily
Solution Approach 1:
The patent performs partial decoding by executing the first stage for all MCUs to ensure complete image availability for future operations, but limits the second stage to only those MCUs required for the current display. This approach balances adaptability with efficiency, maintaining the option to access any part of the image while avoiding unnecessary processing time for currently non-displayed portions.
Data Source
AI summary
An embodiment of a method for decoding large images performed by a processing unit, comprises the following steps. A compressed bit stream of a minimum code unit (MCU) of an image is acquired. The acquired bit stream is decoded by performing a first stage of a image decoding procedure to generate a temporary decoding result of the acquired bit stream. It is determined whether the MCU requires display. If so, the generated temporary decoding result is decoded by performing a second stage of the image decoding procedure to generate display data of the acquired bit stream. The temporary decoding result of the acquired bit stream is utilized to decode another MCU of the bit stream.