UNIT I
DIGITAL IMAGE FUNDAMENTALS
1.1. Define Image.
An Image may be defined as a two dimensional function f(x,y) where x & y are spatial
(plane) coordinates, and the amplitude of f at any pair of coordinates (x,y) is called intensity or
gray level of the image at that point. When x,y ...
1.1. Define Image.
An Image may be defined as a two dimensional function f(x,y) where x & y are spatial
(plane) coordinates, and the amplitude of f at any pair of coordinates (x,y) is called intensity or
gray level of the image at that point. When x,y and the amplitude values of f are all finite,
discrete quantities we call the image as Digital Image.
1.2. Define Image Sampling.
Digitization of spatial coordinates (x,y) is called Image Sampling. To be suitable for
computer processing, an image function f(x,y) must be digitized both spatially and in
magnitude.
1.3. Define Quantization.
Digitizing the amplitude values is called Quantization. Quality of digital image is
determined to a large degree by the number of samples and discrete gray levels used in sampling
and quantization.
1.4. What is Dynamic Range?
The range of values spanned by the gray scale is called dynamic range of an image.
Image will have high contrast, if the dynamic range is high, and image will have dull washed
out gray look if the dynamic range is low.
1.5. Define Mach band effect.
The spatial interaction of Luminance from an object and its surround creates a
phenomenon called the mach band effect.
1.6. Define Brightness.
Brightness of an object is the perceived luminance of the surround. Two objects with
different surroundings would have identical luminance but different brightness.
1.7. What is meant by Tapered Quantization?
If gray levels in a certain range occur frequently while others occurs rarely, the
quantization levels are finely spaced in this range and coarsely spaced outside of it. This method
is sometimes called Tapered Quantization.
1.8. What do you meant by Gray level?
Gray level refers to a scalar measure of intensity, that ranges from black to grays and
finally to white.
Prepared by A.Devasena., Associate Professor., Dept/ECE Page 1
,EC2029- Digital Image Processing VII Semester ECE
1.9. What do you meant by Color model?
A Color model is a specification of 3D-coordinates system and a subspace within that
system where each color is represented by a single point.
1.10. List the hardware oriented color models.
The hardware oriented color models are as follows,
i. RGB model
ii. CMY model
iii. YIQ model
iv. HSI model
1.11. What is Hue of saturation?
Hue is a color attribute that describes a pure color where saturation gives a measure of
the degree to which a pure color is diluted by white light.
1.12. List the applications of color models.
The applications of color models are,
i. RGB model--- used for color monitor & color video camera
ii. CMY model---used for color printing
iii. HIS model----used for color image processing
iv. YIQ model---used for color picture transmission
1.13. What is Chromatic Adoption?
The hue of a perceived color depends on the adoption of the viewer. For example, the
American Flag will not immediately appear red, white, and blue, the viewer has been subjected
to high intensity red light before viewing the flag. The color of the flag will appear to shift in
hue toward the red component cyan.
1.14. Define Resolutions.
Resolution is defined as the smallest number of discernible detail in an image. Spatial
resolution is the smallest discernible detail in an image and gray level resolution refers to the
smallest discernible change is gray level.
1.15. Write the M X N digital image in compact matrix form?
f(x,y )= f(0,0) f(0,1)………………f(0,N-1)
Prepared by A.Devasena., Associate Professor., Dept/ECE Page 2
, EC2029- Digital Image Processing VII Semester ECE
1.16. Write the expression to find the number of bits to store a digital image?
The number of bits required to store a digital image is
b=M X N X k
When M=N, this equation becomes
b=N^2k
1.17. What is meant by pixel?
A digital image is composed of a finite number of elements, each of which has a
particular location of value. These elements are referred to as pixels or image elements or
picture elements or pels elements.
1.18. Define digital image.
A digital image is an image f(x,y), that has been discretized both in spatial coordinates
and brightness.
1.19. List the steps involved in digital image processing.
The steps involved in digital image processing are,
i.Image Acquisition.
ii.Preprocessing.
iii.Segmentation.
iv.Representation and description.
v.Recognition and interpretation.
1.20. What is recognition and interpretation?
Recognition is a process that assigns a label to an object based on the information
provided by its descriptors. Interpretation means assigning to a recognized object.
1.21. Specify the elements of DIP system.
The elements of DIP system are,
i.Image acquisition.
ii.Storage.
iii.Processing.
iv.Communication.
v.Display.
1.22. List the categories of digital storage.
The categories of digital storage are,
i.Short term storage for use during processing.
ii.Online storage for relatively fast recall.
iii. Archical storage for frequent access.
1.23. Write the two types of light receptors.
The two types of light receptors are,
i.Cones.
ii.Rods.
Prepared by A.Devasena., Associate Professor., Dept/ECE Page 3
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