Level Set Based Selection Editing

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Jaegwang Lim, Byungmoon Kim, Sunil HadapLevel Set Based Selection Editing


Photoshop Selection Tools

Quick Selection Magic Wand Magnetic Lasso

Hard to modify the selection

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【 Quick selection 】【 Magic wand 】【 Magnetic Lasso 】


Selection Using Brush-Tool

Using brush tools for selection Can modify selection boundary by painting/erasing

Not in incredibly awesome way, because Should create a separate layer Simply, brush is not designed for selection No automatic snapping to edges No interactive grow/shrink No direct control on smoothness of selection curves

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【 Brushing 】【 Selection 】【 Remove Brush layer 】


Our Idea

A New Selection Tool Use Special Selection Brush Paint region Snapping To Edge Grow/Shrink Curvature Control

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Our Idea : Grow/Shrink

Source and Sink in red region Grow and Shrink in blue region

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Sinking

【 Source, Grow 】【 Sink, Shrink 】

Sourcing

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Our Idea : Brush Definition

Hard region inside Soft region outside

Fall off function:

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Our Idea : Brush Definition

DEMO

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Our Idea : Snap

Detect edge and automatically snap to the edge Only inside the soft region

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Our Idea : Snap

DEMO

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Level Set

Level set is a distance field Selected region is where level set is negative Selection curve is where level set is zero

Selection curves moves when level set is updated by Level set advection equation: We can define the velocity

Level set can be slow when iterated for all pixels, so we Update the level set only inside the cursor Use adaptive quad tree grid

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Previous Works on Level Set Based Image Segmentation

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Cannot be used since Edge-based

Leak problem Region-based

Useful only when foreground and background have different color (statistics)

We focus on local editing


Locally Solving Level Set on Adaptive Grid

Use Grizzly quad tree template

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Snapping

Direction vector to image edge (LUMA)

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Snapping

Velocity to image edge:

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Edge of imageInterface curve

Velocity to edge


Modifying Selection

Selection could spill at weak image edge But we can easily modify selection.

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Spill

Weak Edge


Modifying Selection

We modify selection to overcome at strong image edge The closer to center of circle the stronger the velocity. Selection curve close to center of circle is easy to overcomed

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Strong edgeStrong edge can be overcomed with red circleif you want to select beyond


Nudging (Dragging Curves)

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Interface curve

DraggingVelocity

In progress…


Demo

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Future Works

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Nudging Local region-based or graph-cut segmentation


Technology

Level Set Based Selection Editing