Digital Image Processing Slides

2. Spatial Aliasing : is insufficient sampling of data along the
space axis, which occurs because of the insufficient spatial
resolution of the acquired image.
Critical Sampling Distance: is the Sampling Distance
corresponding to the Nyquist Rate.

3. Aliasing of a undersampled 1D
sinusoidal signal
Aliasing of a undersampled 2D
image

4. Aliasing problem of a
downsampled image
Aliasing problem avoided by using
band limiting Low Pass Filter.

6. Spatial Domain Methods: manipulates the pixel of a given
image for enhancement.
Frequency Domain Methods: manipulates the Fourier transform
of a given image for enhancement.

7. f(x,y) : input
g(x,y) : output
T : transformation function
g(x,y)=T[f(x,y)]

8. (x,y)
3x3 neighborhood (mask)

9. Point Processing: enhancement at any point in an image
depends only the gray-level at that point.
Mask Processing/Filtering: where the values of the mask
coefficients determine the nature of the process.

10. Contrast: is the difference in visual properties making an
object/image distinguishable from other objects and the
background.

11.  We have looked at:
 What is aliasing?
 What is anti-aliasing?
 What is image enhancement?
 Image enhancement in spatial domain
 Next time we will talk about contrast
stretching

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