Question:

A 4 × 4 digital image has pixel intensities (U) as shown in the figure. The number of pixels with \( U \leq 4 \) is:

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In digital images, when analyzing pixel intensities, always look for the specific threshold conditions (like \( U \leq 4 \)) and count the pixels that satisfy the condition across the entire matrix.

Updated On: Apr 4, 2025

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The Correct Option is C

Solution and Explanation

We are asked to find how many pixels have intensities less than or equal to 4.
Let’s go through the matrix and count the number of pixels that satisfy \( U \leq 4 \).
The given matrix of pixel intensities is:

Row 1: 0, 1, 0, 2 (all are \( \leq 4 \)) - Count: 4
Row 2: 4, 7, 3, 3 (4, 3, 3 are \( \leq 4 \)) - Count: 3
Row 3: 5, 5, 4, 4 (4, 4 are \( \leq 4 \)) - Count: 2
Row 4: 6, 7, 3, 2 (3, 2 are \( \leq 4 \)) - Count: 2

Total count: \( 4 + 3 + 2 + 2 = 11 \)

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	Reference Data
	Class 1	Class 2	Class 3	Class 4
Classified Data	Class 1	320	8	7	3
Class 2	12	270	6	2
Class 3	9	6	410	5
Class 4	14	2	3	350

Location of pixels in input image (Row, Column)	Brightness Value
(5, 3)	9
(5, 4)	11
(6, 3)	14
(6, 4)	12

Questions Asked in GATE DA exam

Consider the following pseudocode.

Create empty stack S
Set x = 0, flag = 0, sum = 0
Push x onto S
while (S is not empty){
    if (flag equals 0){
        Set x = x + 1
        Push x onto S
    }
    if (x equals 8):
        Set flag = 1
    if (flag equals 1){
        x = Pop(S)
        if (x is odd):
            Pop(S)
        Set sum = sum + x
    }
}
Output sum

The value of \( sum \) output by a program executing the above pseudocode is:

GATE DA - 2025
Data Structures

View Solution

Consider the following Python code snippet.

def f(a, b):
    if (a == 0):
        return b
    if (a % 2 == 1):
        return 2 * f((a - 1) / 2, b)
    return b + f(a - 1, b)

print(f(15, 10))

The value printed by the code snippet is 160 (Answer in integer).

GATE DA - 2025
Recursion