Question

A CCD array element in a remote sensing sensor measures incoming radiation and its output voltage varies linearly between 0 V to 5 V. This voltage is converted to an 8-bit digital image using an analogue to digital convertor (ADC). The ADC has a linear response without bias or noise. If the output image pixel has a digital number of 100, the input voltage to the ADC would be \rule{2cm{0.15mm} V (rounded off to 2 decimal places).}

Hint:

For an 8-bit image, divide the voltage range by 255 to find voltage per digital number. Multiply it by the DN to get input voltage.

Answer 1

Correct Answer: 1.95

For an 8-bit system, the digital number (DN) can range from 0 to 255. The voltage corresponding to each DN level is given by: \[ {Voltage per DN} = \frac{5\,{V}}{255} \approx 0.0196\,{V} \] If the DN = 100, then: \[ {Voltage} = 100 \times 0.0196 = 1.96\,{V} \] Final Answer: \fbox{1.96 V}