M a n g a Co lo r iza t io n

Y in g g e QuT ie n -Ts in W o n g

Ph en g -A n n H e n g

The Chinese University of Hong Kong

MXMLLN Montgomery

Ou t l in e

Paper•Introduction

– Motivation– Previous Work

•Contributions– Pattern Segmentation– Colorization

●ResultsCritique

•Motivation•Technique Generalization

MXMLLN Montgomery

Introduction Contributions Results Critique

b

M o t iv a t io n

ProblemI. Manga are seldom colored due to the time and labor involved.

II. The fine artistic details used to create the visual content and atmosphere are ill-suited for digital colorization techniques, i.e.,

I.Half-toning

II.Screening

III.Hatching

Introduction Contributions Results Critique

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Pr ev io u s W o r k

User-Directed Colorization●User scribbles color in desired regions●Using constraint quadratic optimization problem, colorization is achieved under the assumption that adjacent pixels with similar intensities should be similarly colored

Introduction Contributions Results Critique

MXMLLN Montgomery

Pr ev io u s W o r k

Semi-Automated Colorization●Colorization by matching swatches of greyscale image to reference color image●Auto regression filtering from the relationship between A and A', applied to input image B to create B'●Colorization by transferring color from an example segmented image using high-level pixel context

Introduction Contributions Results Critique

MXMLLN Montgomery

MXMLLN Montgomery

Introduction Contributions Results Critique

Pr ev io u s W o r k

Limitations●Works for intensity continuity, like photographs and videos ●Is unable to handle pattern continuity, like illustrations

Pr ev io u s W o r k

Texture-Based Segmentation●Texture is classified, segmented, and synthesized based on texture properties of repeated elements:

● Size● Aspect ratio● Orientation● Brightness● Density

Introduction Contributions Results Critique

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Im p lem en t a t io n

Color propagation employs a zero surface, geometric, level set method

For more details, please refer to the text

Introduction Contributions Results Critique

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Co n t r ib u t io n s

Pattern-continuous regions● Uniformly sample along user scribble to compute pattern features:

● Cluster feature patterns● Identify major cluster● Find average of major cluster

● Allows some error in scribbling over unintended areas

Introduction Contributions Results Critique

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Co n t r ib u t io n s

Pattern-continuous regions● Propagate color until pattern reaches abrupt change● This step allows both splitting and merging between boundaries

● Disjoint regions can be colored with single scribble

Introduction Contributions Results Critique

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Co n t r ib u t io n s

Intensity-continuous regions● Leak proofing prevents propagation from leaking through gaps

Introduction Contributions Results Critique

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Co n t r ib u t io n s

Colorization● Stroke-preserving colorization

● Colorization is achieved by bleeding out from strokes and patterns

Introduction Contributions Results Critique

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Co n t r ib u t io n s

Colorization● Pattern-to-shading

● Hatching and screening shading effects can be portrayed smoothly by color shading

Introduction Contributions Results Critique

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Co n t r ib u t io n s

Colorization● Multi-color transition

● Colors are blended together based on their distance from the user scribble

Introduction Contributions Results Critique

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Res u lt s

Limitations● System regards overlapped patterns as distinct

Introduction Contributions Results Critique

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Cr it iq u e

Motivation● Mangas are not colored because of the extensive printing cost● Many techniques, such as hatching and screening shading, may actually be less labor intensive in color

Introduction Contributions Results Critique

MXMLLN Montgomery

Cr it iq u e

Technique generalization● The authors never identify other applications of their technique

● More broadly than manga, their work is suitable for any intensity-homogenous images and videos.

● Including additional applications broadens the scope and reader base of a publication

Introduction Contributions Results Critique

MXMLLN Montgomery