# Digital Image Processing Questions and Answers – Relationships between Pixels

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This set of Digital Image Processing Multiple Choice Questions & Answers (MCQs) focuses on “Relationships between Pixels”.

1. In 4-neighbours of a pixel p, how far are each of the neighbours located from p?
a) one pixel apart
b) four pixels apart
c) alternating pixels
d) none of the Mentioned

Explanation: Each pixel is a unit distance apart from the pixel p.

2. If S is a subset of pixels, pixels p and q are said to be ____________ if there exists a path between them consisting of pixels entirely in S.
a) continuous
b) ambiguous
c) connected
d) none of the Mentioned

Explanation: Pixels p and q are said to be connected if there exists a path between them consisting of pixels entirely in S.

3. If R is a subset of pixels, we call R a _________ of the image if R is a connected set.
a) Disjoint
b) Region
c) Closed

Explanation: R is called a Region of the image.

4. Two regions are said to be ___________ if their union forms a connected set.
b) Disjoint
c) Closed
d) None of the Mentioned

Explanation: The regions are said to be Adjacent to each other.

5. If an image contains K disjoint regions, what does the union of all the regions represent?
a) Background
b) Foreground
c) Outer Border
d) Inner Border

Explanation: The union of all regions is called Foreground and its complement is called the Background.

6. For a region R, the set of points that are adjacent to the complement of R is called as ________
a) Boundary
b) Border
c) Contour
d) All of the Mentioned

Explanation: The words boundary, border and contour mean the same set.

7. The distance between pixels p and q, the pixels have a distance less than or equal to some value of radius r centred at (x,y) is called :
a) Euclidean distance
b) City-Block distance
c) Chessboard distance
d) None of the Mentioned

Explanation: Euclidean distance is measured using a radius from a defined centre.

8. The distance between pixels p and q, the pixels have a distance less than or equal to some value of radius r, form a diamond centred at (x,y) is called :
a) Euclidean distance
b) Chessboard distance
c) City-Block distance
d) None of the Mentioned

Explanation: Formation of a diamond is measured as City-Block distance.

9. The distance between pixels p and q, the pixels have a distance less than or equal to some value of radius r, form a square centred at (x,y) is called :
a) Euclidean distance
b) Chessboard distance
c) City-Block distance
d) None of the Mentioned

Explanation: Distance measured by forming a square around the centre is called Chessboard distance.

10. Which of the following is NOT is not a type of Adjacency?
d) None of the Mentioned 