Image Filtering for Run-Length Encoding of ClearType Text
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Solution Overview
Problem
Run length encoding of images with clear type text results in inefficient encodings due to lack of repeating pixels and extra bits required for unique pixel colors, leading to increased bandwidth usage and reduced encoding efficiency.
Innovation Solution
An encoder performs image filtering by calculating the RGB Euclidean geometric distance between pixels and changing the color of a current pixel to match the prior pixel if the distance is below a threshold, reducing shade variations and increasing runs of repeating pixels, which are then encoded using run length encoding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If clear type text is used to improve text appearance and smoothness, then visual quality is improved, but encoding efficiency deteriorates due to lack of repeating pixels and extra bits required for unique pixel colors
Solution Approach 1:
The patent changes the color parameter of pixels by calculating RGB Euclidean geometric distance between current and prior pixels. When the distance is below a threshold, the current pixel's color is modified to match the prior pixel, reducing unique color values while maintaining visual quality. This parameter change enables better run length encoding efficiency.
Solution Approach 2:
The patent introduces an intermediary filtering process between image capture and encoding. This filtering step calculates color distances and modifies pixel values, acting as a mediator that bridges the gap between maintaining visual quality and achieving encoding efficiency. The threshold-based filtering serves as the intermediary mechanism.
2Manufacturing precision
If all unique pixel colors are preserved to maintain image quality, then image quality is maintained, but bandwidth usage increases due to more bits required for encoding
Solution Approach 1:
The patent modifies pixel color parameters by comparing RGB Euclidean distances and adjusting colors that fall within the threshold range. This reduces the total number of unique color values in the image, directly decreasing the bits required for encoding while keeping perceptible quality intact.
Solution Approach 2:
The patent sacrifices minor, imperceptible color variations (cheap, short-living differences) to achieve greater overall efficiency. By removing subtle shade variations that the human eye cannot detect, the system reduces encoding requirements without meaningful loss in perceived image quality.
3Ease of manufacture
If run length encoding is applied directly to images with shade variations, then encoding is simpler, but encoding efficiency is reduced due to lack of repeating pixels
Solution Approach 1:
The patent performs preliminary filtering action before the main encoding process. By pre-calculating color distances and adjusting pixel values to reduce variations, the system prepares the image data in advance to be more suitable for run length encoding, thereby improving overall encoding efficiency without complicating the encoding algorithm itself.
Solution Approach 2:
The patent changes pixel color parameters through threshold-based filtering, creating more uniform regions with repeating pixel values. This parameter modification increases the effectiveness of subsequent run length encoding by creating longer runs of identical values.
Data Source
AI summary
An encoder includes a processor and a memory coupled thereto. A digital image to be encoded is stored in the memory. The digital image includes an array of pixels, with each pixel having an RGB color value associated therewith. Image filtering is performed on the digital image and includes calculating an RGB Euclidean geometric distance between a current pixel and a prior pixel, comparing the calculated RGB Euclidean geometric distance to a threshold, and changing the RGB color value of the current pixel to the same RGB color value as the prior pixel when the calculated RGB Euclidean geometric distance is less than the threshold. Run length encoding is performed on the filtered digital image.