Encoder-Optimized Text Rendering for Sparse Transform Coding
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Solution Overview
Problem
Existing image coding processes struggle to efficiently encode text strings within digital raster images, particularly when the text is rendered concurrently with image synthesis, as they lack methods to optimize the layout for block-wise transform coding, leading to suboptimal bandwidth and storage usage.
Innovation Solution
A method for rendering text strings in digital raster images that involves partitioning the image area into coding blocks, representing the text as graphical elements, and applying a spectrum sparsening operation to modify the layout, ensuring the spectrum is sparser, thus reducing the number of nonzero transform coefficients and enabling more efficient encoding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If text is rendered using conventional methods without spectrum sparsening, then the text string is preserved accurately, but the bitrate required for encoding increases and compression efficiency deteriorates
Solution Approach 1:
The patent applies spectrum sparsening operations to the tentative layout of graphical elements before rendering the final image. This preliminary modification of the layout (adjusting positions, orientations, or sizes of text elements) optimizes the spectral characteristics of the image blocks, ensuring that the subsequent transform coding produces sparser coefficients without altering the perceived text content.
2Loss of energy
If the tentative layout is modified to achieve spectrum sparsening, then the bitrate for encoding is reduced, but the layout constraints may be violated
Solution Approach 1:
The patent modifies parameters of the graphical elements (position, orientation, size) within the tentative layout to achieve spectrum sparsening. These parameter changes are constrained to maintain compliance with specified layout requirements, thereby reducing bitrate without violating layout constraints.
3Device complexity
If conventional text rendering is used without optimization for block-wise transform coding, then the rendering process is simple, but the compression performance deteriorates
Solution Approach 1:
The patent introduces a preliminary spectrum sparsening step that modifies the tentative layout of graphical elements before rendering. This additional processing step optimizes the spectral characteristics of the image blocks, leading to sparser transform coefficients and improved compression efficiency without significantly complicating the overall rendering pipeline.
Data Source
AI summary
A method for rendering a text string in a digital raster image suitable for block-wise transform coding, the method comprising: obtaining a partition of an image area into coding blocks for the block-wise transform coding; representing the text string as a plurality of graphical elements from a typeface which are arranged according to a tentative layout in the image area, wherein the tentative layout defines at least a position, orientation and size of each graphical element; modifying the tentative layout by applying a spectrum sparsening operation to at least one nonempty coding block, thereby obtaining a modified layout; and rendering a digital raster image of the graphical elements arranged according to the modified layout.