What do you understand by zero memory operations?

Mumbai University > Computer Engineering > Sem 7 > Image Processing

Marks: 5 Marks

Year: Dec 2015

  • In zero memory operations, output image pixel value is obtained directly processing input image image pixel values. Output pixel value at (x, y)position depends on single input pixel at (x, y).
  • For every input image pixel value, Transformation function gives corresponding output image pixel value, no memory location is required to store intermediate results.

    The various Zero Memory Point operations are:

    • Contrast Stretching Transformation
    • lipping and Thresholding
    • Digital Negative Transformation
    • Logarithmic Transformation
    • Power Law Transformation
    • Intensity Level Slicing Transformation and
    • Bit Level Slicing Transformation.

    Let r denotes input image pixel valueand S denotes output image pixel value

    Then S=T(r); where T is any Zero memory point operation Transformation function.

    Point processing Techniques:

1.Contrast Stretching Transform:

Contrast Stretching Tx function increases the dynamic range of modified image.

  • It is defined as S=T(r)

    Where T is Contrast Stretching Tx function such that,

$$s=\begin{bmatrix}ar & & 0 \leq r \leq a \\ S1+ \beta (r-a) & & a \leq r\leq b \\ S2+ \gamma(r-b) & & b \lt r \leq L-1 \end{bmatrix}$$

enter image description here

2.Clipping and Thresholding Transformation:

  • Clipping is extension of Contrast Stretching Tx function.
  • Consider of Contrast Stretching Tx function:

    Case 1: When α=0 and γ=0

$$s=\begin{bmatrix}0 & & 0 \leq r \leq a \\ S1+ \beta (r-a) & & a \leq r\leq b \\ S2 & & b \lt r \leq L-1 \end{bmatrix}$$

enter image description here

Case 2: When α=0,γ=0 and S1=0

$$s=\begin{bmatrix}0 & & 0 \leq r \leq a \\ \beta (r-a) & & a \leq r\leq b \\ S2 & & b \lt r \leq L-1 \end{bmatrix}$$

enter image description here

  • Thresholdng Transformation function is defined as S=T(r)

    Such that,

    S= enter image description here

3.Digital Negative Transformation:

  • Digital Negative reverses the gray scale of input image.
  • It is defined as S=T(r)

    Where T is the Digital Negative Tx Function

enter image description here

Such that, S=(L-1)-r

  • It is used to obtain Negative print of photograph and to display X-ray images.
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