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

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

The error matrix resulting from randomly selected test pixels for a classified image is given below. The Producer’s accuracy of class 1 is __________ % (rounded off to 1 decimal place).
| 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 | |
The brightness values of four pixels in the input image are shown in the table below. The image is rectified using nearest neighbor intensity interpolation, and the pixel at location \( (5, 4) \) in the output image is to be filled with the value from coordinate \( (5.3, 3.7) \) in the input image. The brightness value of the pixel at location \( (5, 4) \) in the rectified output image is __________ (Answer in integer).
| Location of pixels in input image (Row, Column) | Brightness Value |
|---|---|
| (5, 3) | 9 |
| (5, 4) | 11 |
| (6, 3) | 14 |
| (6, 4) | 12 |
A through hole of 10 mm diameter is to be drilled in a mild steel plate of 30 mm thickness. The selected spindle speed and feed for drilling hole are 600 revolutions per minute (RPM) and 0.3 mm/rev, respectively. Take initial approach and breakthrough distances as 3 mm each. The total time (in minute) for drilling one hole is ______. (Rounded off to two decimal places)
In a cold rolling process without front and back tensions, the required minimum coefficient of friction is 0.04. Assume large rolls. If the draft is doubled and roll diameters are halved, then the required minimum coefficient of friction is ___________. (Rounded off to two decimal places)