The structure of intensity transformation and respective filters

1. Intensity Transformations
and Spatial Filtering
intensity transformations
spatial filtering

2. Definitions
• Intensity transformations operate on single pixels of an image for
tasks such as contrast manipulation and image thresholding
• Spatial filtering performs operations on the neighborhood of every
pixel in an image

3. Spatial processing
• Spatial domain: g(x, y) = T[ f (x, y)]
Contrast stretching Thresholding

4. NEGATIVIZIMI, LOGs
• s = L - 1 – r
• s = c log(1 + r)

5. POWER-LAW (GAMMA) TRANSFORMATIONS
• s = c r power γ

6. C = 1, γ = 0.6; 0.4; 03.
• A further decrease of gamma to 0.3
enhanced a little more detail in the
background, but began to reduce
contrast to the point where the image
started to have a very slight “washed-
out” appearance, especially in the
background.
• The best enhancement in terms of
contrast and discernible detail was
obtained with g = 0. 4
• A value of g = 0.3 is an approximate
limit below which contrast in this
particular image would be reduced to
an unacceptable level.

7. PIECEWISE LINEAR TRANSFORMATION FUNCTIONS
• The main disadvantage of these functions is that their specification requires considerable
user input

8. Intensity-Level Slicing

9. Bit-Plane Slicing

10. HISTOGRAM PROCESSING

11. HISTOGRAM EQUALIZATION

12. EXAMPLE
• Suppose that a 3-bit image (L = 8) of size 64 × 64, (MN = 4096)