CAGD&CG

Color Analogies and its applications

reporter:Shuangmin Chen

CAGD&CG

Question• On TV,we often see that a scene with diffe

rent seasons show its time flies. Because the speed of changing the films is so fast.

• I found some pictures about a scene with different seasons on the internet.They are made by the photographers as heard.

CAGD&CG

Pictures• 1.

• 2.P1

P2Any flaws???

Any difficulties???

CAGD&CG

Discussion• Our question:if we can deal with a picture

and can get different seasons pictures,that’s wonderful!But it’s a little difficult.

• Discussion:Is there any way that we can make it???—maybe

CAGD&CG

My job—Color Analogies• Two papers:

1.Image Analogies

2.Color Transfer between ImagesColor Analogies

result

CAGD&CG

Introduction to the two papers• Image Analogies

---Aeron Hertzmann et.al

(2001Siggraph)

Style transfer

CAGD&CG

Introduction to the two papers• Color Transfer between Images

---- Erik Reinhard et.al

Color transfer

CAGD&CG

Guideline • Color space introduction

—process in color space

• Formula in Color Transfer between images

• Similar to a new formula

• Results show

l

CAGD&CG

Introduction to RGB • We can get any color by blending with RG

B

Definition with cubic

CAGD&CG

Introduction to lab color space• In Photoshop,the range of l is 0 to 100;and

in color palete,the ranges of a and b are both 120 to -120.

CAGD&CG

Why decorrelation is better?

• Apply different operations in different color channels that without undesirable crosschannel artifacts.

• The data in lab space is more compressed (log space)

• RGB:correlations between the different channel’s values. (0,0,0) - (255,255,255)

CAGD&CG

Guideline • Color space introduction

—process in color space

• Formula in Color Transfer between images

• Analogy to a new formula

• Results show

l

CAGD&CG

Color constancy correction• Subtract the mean from the data points

• Scale the data points comprising the synthetic image by factors determined by the respective standard deviation

CAGD&CG

Color constancy correction• add the averages computed for the photag

raph.

+ <at>

+ <bt>

+ <lt>

CAGD&CG

Formula in Color Transfer between images

( / )( )l l l l

src dst src src src dstl l m m

( / )( )src dst src src src dstm m

( / )( )src dst src src src dstm m dst:destination(target);src:source;

standard deviation m– mean value

Linear equation

CAGD&CG

Guideline • Color space introduction

—process in color space

• Formula in Color Transfer between images

• Analogy to a new formula

• Results show

l

CAGD&CG

Analogy to a new formula• Color Transfer:

( ) ( ) ::A dst B src B B 已知 ？

B

A B’src dst

A,B are given!!!

CAGD&CG

Formula in Color Transfer between images

/l l

dst src l

dstm

( / )( )l l l l

src dst src src src dstl l m m ( / )( )src dst src src src dstm m ( / )( )src dst src src src dstm m

linear equation:

slope k = (注 :src,dst是已知的 )

through a point:( , )l

srcm

( ) ( ) ::A dst B src B B 已知 ？

(1)

(2)

(3)

CAGD&CG

Analogy to a new formula• Image Analogies

BBAA ？已知 ::A,A’,B are given!!!

CAGD&CG

Analogy to a new formula

' :: 'A A B B 已知 ？

(1)

:: 'A B C C 已知 ？

(2)

Details show on blackboard!

CAGD&CG

Results show

result 1

CAGD&CG

Results show

result 2

CAGD&CG

Results show

result 3

CAGD&CG

Results show

result 4