1. By
Mr. PREM RANJAN
M.Tech SWE
Roll No: 01/SWE/15

2.  Set of digital processing functions
 Designed to highlight or suppress specific
feature in an image based on their spatial
frequency
 Spatial frequency- concept of image
texture(frequency of variation in tone)

3.  Rough textured area of an image with sudden
change in tone over a small area have high
spatial frequency
 Smooth textured area of an image with little
variation in tone over a small area/ several
pixel have low spatial frequencies

4.  Moving a window of few pixel in dimension
(e.g. 3×3, 5×5,7×7, etc.) over each pixel in the
image.
 Applying mathematical technique
 Replacing the central pixel with the new value
 New image has been generated
 Change in calculation and individual pixel in
the filter window, filters can be designed to
enhanced or suppress different type of features

5. 1. Low Pass-filter
2. High Pass-filter
3. Directional or Edge detection filters

6.  Designed to emphasize larger (low frequency)
& deemphasize the high frequency (local
details)
 Homogeneous areas of similar tone
 Reduce the smaller detail in an image
 Generally serves to smooth the appearance of
an image
 E.g. Average and median filters

7. Fig. 1. Input image Fig.2. Filter applied Fig.3 . Output image

8.  Serve to sharpen the appearance of the detail
in image
 Emphasize high frequency(local details)
Steps of Uses of high-pass filter
 First apply a low pass filter to an image
 Then subtract the result from the original
image
 Gives high spatial frequency information
which is known as high boost filter

9. Fig.1. Input Image Fig. 2. Output image

10.  Designed to highlight linear features, such as
road or filed boundaries
 Enhance features which are oriented in
specific direction
 Useful in application such as geology, for
detection of linear geographic structures

11. Fig.1. Input image Fig. 2. Output image

12. THANK YOU