Question 33.10: Pixels and resolution. A 6-MP (6-megapixel) digital camera o......
Pixels and resolution. A 6-MP (6-megapixel) digital camera offers a maximum resolution of 2000 \times 3000 pixels on a 16-\mathrm{mm} \times 24-\mathrm{mm} CCD sensor. How sharp should the lens be to make use of this resolution?
APPROACH We find the number of pixels per millimeter and require the lens to be at least that good.
We can either take the image height (2000 pixels in 16 \mathrm{~mm}) or the width (3000 pixels in 24 \mathrm{~mm} ):
\frac{3000 \text { pixels }}{24 \mathrm{~mm}}=125 \text { pixels } / \mathrm{mm}
We would want the lens to be able to resolve at least 125 lines or dots per \mathrm{mm} as well, which would be a very good lens. If the lens is not this good, fewer pixels and less memory could be used.
NOTE Increasing lens resolution is a tougher problem today than is squeezing more pixels on a CCD or CMOS. The sensor for high MP cameras must also be physically larger for greater light sensitivity (low light conditions).