A \(4 \times 4\) digital image has pixel intensities (\(U\)) as shown in the figure. The number of pixels with \(U \le 4\) is:
| 0 | 1 | 0 | 2 |
| 4 | 7 | 3 | 3 |
| 5 | 5 | 4 | 4 |
| 6 | 7 | 3 | 2 |
Answer
(C)
Explanation
The condition \(U \le 4\) includes 4, so count every pixel with value 0, 1, 2, 3 or 4, row by row:
- Row 1 (0, 1, 0, 2): all 4 pixels
- Row 2 (4, 7, 3, 3): 3 pixels
- Row 3 (5, 5, 4, 4): 2 pixels
- Row 4 (6, 7, 3, 2): 2 pixels
The total is \(4 + 3 + 2 + 2 = 11\). As a check, only five pixels are above 4 (5, 5, 6, 7, 7), and \(16 - 5 = 11\). Leaving out the three pixels equal to 4 would give 8, option B.
Answer: C