Foveated Display Dithering With Fixed Blocks to Prevent Ghosting

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Solution Overview

Problem

Visual artifacts such as image retention and ghost images occur in dynamically foveated content due to changing dither patterns over time, which are perceptible to the human eye as the gaze-dependent dither patterns shift with the viewer's gaze.

Innovation Solution

Implement gaze-independent dither techniques by defining dither blocks based on the native locations of pixels rather than foveation groups, using a multi-step linear-feedback shift register to map differently-sized foveation groups to these blocks, thereby maintaining uniform dither patterns across frames.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If gaze-dependent dither patterns are used to adapt to viewer's gaze in dynamically foveated content, then the dithering adapts to the foveated regions, but visual artifacts such as image retention and ghost images occur due to changing dither patterns between frames

Engineering Contradiction:

Improvedither pattern adaptation to gazeVSAvoidvisual artifacts

Core Design Contradiction:

Adaptability or versatilityVSObject-affected harmful factors

Solution Approach 1:

The display area is divided into multiple dither blocks with fixed boundaries, and each block is processed with a consistent dither pattern. This segmentation approach ensures that while the overall dithering adapts to gaze through foveated content processing, each local block maintains pattern consistency, preventing visual artifacts caused by pattern changes between frames.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Instead of making dither patterns change with gaze (gaze-dependent), the patent inverts the approach by using fixed dither patterns regardless of gaze position. The adaptation to foveated content is achieved through other means while maintaining static dither patterns, thereby eliminating the visual artifacts caused by dynamic pattern changes.

Inventive Principle:

Principle #13The other way round (Inversion)

2Adaptability or versatility

If dither patterns change between frames to follow gaze movement, then the dithering remains optimized for the current foveated region, but the human eye perceives the changing patterns as perceptible visual artifacts

Engineering Contradiction:

Improvedither pattern following gazeVSAvoiddither pattern uniformity

Core Design Contradiction:

Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The display is segmented into fixed dither blocks that maintain consistent boundaries across frames. Each block uses a stable dither pattern, ensuring uniformity within blocks. The gaze adaptation occurs at the content level rather than through pattern changes, resolving the conflict between adaptability and uniformity.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent changes the parameter of dither pattern stability by making patterns invariant with respect to gaze position. While other parameters (such as content resolution or processing) may change to adapt to gaze, the dither pattern parameter remains constant, ensuring manufacturing precision and eliminating perceptible artifacts.

Inventive Principle:

Principle #35Parameter changes

3Adaptability or versatility

If dither blocks are defined based on foveation groups that move between frames, then the dithering can adapt to different foveated regions, but foveation boundary mismatches cause dither patterns to change between frames

Engineering Contradiction:

Improvedither blocks with foveation groupsVSAvoiddither pattern consistency

Core Design Contradiction:

Adaptability or versatilityVSStability of the object's composition

Solution Approach 1:

The patent segments the display into fixed dither blocks with stable boundaries that do not move between frames. This segmentation is independent of foveation group movements, ensuring that each block maintains consistent dither patterns while the overall system adapts to different foveated regions through content processing rather than block reconfiguration.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Instead of defining dither blocks based on moving foveation groups, the patent inverts the approach by defining fixed dither blocks first and then adapting the content within those fixed blocks. This inversion ensures pattern consistency while maintaining adaptability through content-level processing.

Inventive Principle:

Principle #13The other way round (Inversion)

Data Source

PatentUS12512034B2Systems and methods for dithering for dynamically foveated content

Publication Date: 2025.12.30 APPLE INC

AI summary

An electronic device that includes a display and an eye tracker configured to collect eye tracking data regarding a gaze of one or more of a user's eyes across the display. The electronic device also includes processing circuitry that is operatively coupled to the display and configured to generate pixel data for frames of content based on the eye tracking data such that the content is configured to be shown on the display in a dynamically foveated manner. The processing circuitry is configured to determine dither blocks, each of which corresponds to a subset of the plurality of pixels. The processing circuitry is configured to apply a dither pattern to the frames of the plurality of frames of content independent of the gaze of one or more of the user's eyes and based on the dither blocks.