Colorization using Optimization Anat Levin Dani Lischinski Yair - - PowerPoint PPT Presentation

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Colorization using Optimization Anat Levin Dani Lischinski Yair - - PowerPoint PPT Presentation

Jul 02, 2023 155 likes •368 views

Colorization using Optimization Anat Levin Dani Lischinski Yair Weiss Colorization Colorization : a computer-assisted process of adding color to a monochrome image or ) movie. (Invented by Wilson Markle, 1970 Motivation Colorizing black

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Colorization using Optimization

Anat Levin Dani Lischinski Yair Weiss

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Colorization: a computer-assisted process of adding color to a monochrome image or

  • movie. (Invented by Wilson Markle, 1970

)

Colorization

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  • Colorizing black and white movies / TV

shows

  • Recoloring color images for special effects

Motivation

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Color 101

  • Typically represented by points in a three

dimensional color space:

  • (Red, Green, Blue)
  • Another option: [Y, U, V]
  • Y - intensity
  • U, V - chromatic channels
  • A simple transformation exists:

[R, G, B] ⇔ [Y, U, V]

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Typical Colorization Process

Images from: “Yet Another Colorization Tutorial” http://www.worth1000.com/tutorial.asp?sid= 161018

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Images from: “Yet Another Colorization Tutorial” http://www.worth1000.com/tutorial.asp?sid= 161018

Typical Colorization Process

  • Delineate region boundary
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Images from: “Yet Another Colorization Tutorial” http://www.worth1000.com/tutorial.asp?sid= 161018

Typical Colorization Process

  • Delineate region boundary
  • Choose region color from palette
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Images from: “Yet Another Colorization Tutorial” http://www.worth1000.com/tutorial.asp?sid= 161018

Typical Colorization Process

  • Delineate region boundary
  • Choose region color from palette
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SLIDE 9

Images from: “Yet Another Colorization Tutorial” http://www.worth1000.com/tutorial.asp?sid= 161018

Typical Colorization Process

  • Delineate region boundary
  • Choose region color from palette
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Process Limitations

  • Requires expertise and time consuming
  • Selecting detailed or fuzzy boundaries is

difficult

  • Tracking regions is difficult (for video)
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Let the user focus on the creative goals, without having to worry about selection!

Our Approach

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Our Approach

Colors are propagated to every pixel in the image.

Grayscale channel Chroma channels

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Pixel Affinity

Assumption: Neighboring pixels with similar intensities should have similar colors.

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Pixel Affinity

Minimize:

r s wrs

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Optimization

  • Find a function U that minimizes:

(subject to the user’s color scribbles)

  • Boils down to solving a system of linear

equations.

  • Do the same for V.
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Colorizing Stills

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Original Colorized

Colorizing Stills

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Colorizing Stills

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13

  • ut of 92 frames

Colorizing Video