digital image processing 3 - cs.uoi.gr...

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  • Digital Image Processing

    Intensity Transformations

    [email protected]

    Images taken from: R. Gonzalez and R. Woods. Digital Image Processing, Prentice Hall, 2008.

  • .

    Image Enhancement:

    :

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    ;

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    ;

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    :

    Fourier

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    ;

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  • 1 :

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  • pixel .

    [,] [,]

    ; ( )z z a

  • pixel [0,255]

    [0,127]

    [128,255]

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    0 255

    128

    128

  • 2 :

  • 3

  • log(1 )s c r

  • log(1 )s r

  • : 1 .

    s c r

  • (MRI )

    0.6s r

  • 0.4s r

  • 0.3s r

  • ;

    =0.6 =0.4 =0.3

  • ( )

  • =3,4 =5.0 ( )

    =3.0 =4.0 =5.0

  • (Gamma Correction)

    =1.8-2.5.

    =1/2.5=0.4

  • .

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    .

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  • (..

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  • -

  • [0-L-1]

    rk: - nk: pixel k

    ;

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  • 4x4=16pixels

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    4

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    0.05

    0.1

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  • 4x4=16pixels

    ;

    ;

    3 3 4 42 3 4 52 3 4 52 3 4 5

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    0 1 2 3 4 5 6 70

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    2

    2.5

    3

    3.5

    4

    4.5

    5

    0 1 2 3 4 5 6 70

    0.05

    0.1

    0.15

    0.2

    0.25

    0.3

    0.35

  • :

  • :

    . . .

    . . .

  • .;

    ;

    ;

  • T

    0, 1r L

    ( )s T r

    1 2 1 2 1 2( ) ( )r r T r T r s s

    0 ( ) 1, 0 1T r L r L

  • T .

    ;

    s r 1-1.

  • (pdf)

    pdf :

    ( ), ( )r sp r p s

    ( )s T r

    1( ) ( ) ( )s r rdrp s p r p r

    ds dsdr

  • (cumulative distribution function, cdf) r. )

    r. )

    1, r=L-1 1.

    0( ) (L 1) ( )

    r

    rs T r p w dw

  • s:

    :

    ;

    ( ) (L 1) ( ) (L 1) ( )r

    r ro

    ds dT r p w dw p rdr dr

    1 1(s) ( )(L 1) ( ) 1s r r

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  • :

    .

  • :

    rk: k sk: k nj: k M,N : ,

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  • 3-bit 64x64 .

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