Ultrasound Gray Scale Mapping Offset for Dynamic Range
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Solution Overview
Problem
Medical diagnostic ultrasound imaging systems face challenges in displaying high dynamic range ultrasound data on displays with lower true gray scale dynamic range, leading to loss of information and undesirable coloration at the ends of the scale.
Innovation Solution
The solution involves offsetting one or two color components by a small increment in ultrasound data mapping to a display, allowing for additional gray levels without noticeable color deviation, and using spatial dithering to increase perceived dynamic range, thereby maintaining the dynamic range of grayscale levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If ultrasound data with high dynamic range is mapped directly to display with lower dynamic range, then the display can show the image, but loss of dynamic range information occurs
Solution Approach 1:
The patent transforms the grayscale mapping from a one-dimensional intensity mapping to a three-dimensional color space mapping. By using RGB color components with offsets, the system exploits the additional dimensions of color space to encode more grayscale levels than the display's native gray scale capability, effectively mapping N-bit ultrasound data to M-bit display output where N > M.
Solution Approach 2:
The patent changes the mapping parameters by introducing offsets to the RGB color components. Instead of mapping ultrasound intensity directly to equal gray levels, the system applies differential offsets to red, green, and blue components, creating perceptible brightness variations while maintaining gray scale appearance. This parameter transformation allows encoding of additional grayscale information within the display's limited dynamic range.
2Loss of information
If tint maps or photopic imaging are used to increase dynamic range, then more grayscale levels can be displayed, but noticeable coloration appears at the ends of the scale
Solution Approach 1:
The patent applies local quality by using different offset strategies for different regions of the grayscale range. The offset values are carefully selected and varied across different intensity levels to maintain perceptual gray scale appearance in diagnostic regions while preserving dynamic range information. This localized adjustment of color component offsets prevents uniform coloration across the entire scale.
Solution Approach 2:
The patent utilizes subtle color changes in the RGB components to encode additional grayscale information. By making minimal, controlled deviations from true gray in the color space, the system creates perceptible brightness differences that correspond to additional ultrasound intensity levels without producing noticeable coloration that would interfere with diagnostic interpretation.
3Loss of information
If color values are offset to provide additional gray levels, then dynamic range is increased, but deviation from gray may become perceptible
Solution Approach 1:
The patent applies partial action by using small, controlled offsets in the RGB color components rather than large deviations. The offset values are carefully chosen to be just sufficient to create perceptible brightness differences for additional grayscale levels while remaining below the threshold of noticeable coloration. This partial deviation strategy maximizes the number of displayable gray levels while maintaining the perceptual appearance of gray scale imaging.
Data Source
AI summary
Gray scale information is mapped to a display with increased dynamic range. Rather than mapping ultrasound data to equal color components, the mapping is offset. The offset may provide a deviation from gray, but the deviation of such a small increment may not be perceptible. Instead, the deviation provides different brightness, which is more easily perceived. The deviation allows for additional levels of gray, such as the 64 levels on a 6-bit display plus any deviation values (e.g., 128 levels for 64 equal color components and 64 with one of the color components offset by one increment). Higher dynamic range ultrasound data maps with less or no loss of dynamic range to a display with a lower true gray scale dynamic range. Spatial dithering may alternatively or additionally increase perception of the dynamic range.