Virtual Hair Coloring Using Frequency Histogram Mapping

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Solution Overview

Problem

Current virtual hair coloring techniques fail to accurately preserve the natural details and variations of hair colors, leading to unrealistic results, and are not capable of real-time processing on mobile devices, which limits their effectiveness in providing a realistic and dynamic virtual try-on experience.

Innovation Solution

A computer-implemented method and system that maps gray levels from a swatch image to a hair portion of an input image using deep neural networks and GPUs, employing a mapping table to determine swatch color values for each pixel, allowing for real-time recoloring and preserving the natural texture and brightness of hair.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If traditional virtual hair coloring methods are used, then processing speed is improved, but realism and detail preservation deteriorate

Engineering Contradiction:
Improveprocessing speedVSAvoiddetail preservation
Core Design Contradiction:
ProductivityVSManufacturing precision

Solution Approach 1:

The patent segments the hair coloring process into multiple independent components: gray level extraction, frequency histogram calculation, mapping table generation, and pixel-level color application. This segmentation allows each component to be optimized independently, enabling real-time processing while preserving detailed hair characteristics through dedicated frequency-matching operations.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent transforms the hair coloring problem from direct color replacement to a parameter-based transformation system. By converting hair pixels to gray levels, calculating frequency distributions, and mapping to target color parameters, the system maintains detailed variations while achieving realistic coloring results at real-time speeds.

Inventive Principle:
Principle #35Parameter changes

2Manufacturing precision

If complex algorithms are used to preserve hair details, then realism is improved, but processing time increases

Engineering Contradiction:
ImproverealismVSAvoidprocessing time
Core Design Contradiction:
Manufacturing precisionVSLoss of time

Solution Approach 1:

The patent performs preliminary actions by pre-calculating frequency histograms from the target swatch image and pre-generating mapping tables that define the relationship between gray levels and target colors. This preliminary processing enables the actual hair coloring to be performed rapidly by simply looking up and applying pre-determined color mappings, achieving both realism and speed.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent replaces complex iterative mechanical coloring algorithms with a direct lookup-based system. Instead of repeatedly adjusting and rendering colors, the system substitutes this with efficient frequency-matching and table-lookup operations, dramatically reducing processing time while maintaining detailed realism through frequency-based color assignment.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

3Measurement precision

If frequency matching is used to preserve color variations, then color accuracy is improved, but computational complexity increases

Engineering Contradiction:
Improvecolor accuracyVSAvoidcomputational complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent introduces frequency histograms and mapping tables as intermediary data structures that bridge the source hair image and target color swatch. These intermediaries simplify the computational process by pre-organizing color relationships, allowing accurate color matching without requiring complex real-time calculations during the actual coloring operation.

Inventive Principle:
Principle #24Intermediary (Mediator)

Data Source

PatentUS20240273857A1Methods and systems for virtual hair coloring
Publication Date: 2024.08.15 LOREAL SA
  • US20240273857A1 patent drawing
  • US20240273857A1 patent drawing
  • US20240273857A1 patent drawing

AI summary

There is provided methods and systems for a hair virtual try on. Gray levels from a swatch image and gray levels from a hair portion of an input image are mapped by matching their respective frequencies to establish a map relationship between the swatch image and the hair portion, wherein the gray levels of the swatch image are associated to respective swatch color values. A pixel in the hair portion is colored based on a swatch color value determined using a gray level of the pixel and the map relationship.