Please help!!! Computer HW?

Question

Specification Scanner X Scanner Y
Max. resolution 2400dpi 3200dpi
Min. resolution 100dpi 150dpi
Color depth 36 bit 24bit
time taken for pre scan 4.5 sec 6.2 sec
(1)which scanner is better for creating large image files? Explain
(2)A 3'4' photo is scanned by Scanner X at the lowest resolution.
(i) calculate the total no. of pixel within the scanned image (which of the above information should i use?)
(ii) if the color depth is 24 bit for each pixel calculate the size of the scanner imge in KB. ( which of the above information i should use again?)

Answer 1

DPI is dots per inch. The more dots, the higher the resolution. So if your only consideration is only max resolution the 3200 is better.

3200 dpi is just that 3200 pixels for each inch. So (lenghtXdpi) x (witdthXdpi) = total number of pixels

Once you know how many pixels you take that times the number of bits for the color depth you are choosing and you have the total number of bits for the whole image. Divide by 1024 and you have it in Kb. Divide again and you get Mb-- those kind of resolutions are going to be Mb not Kb.

That said in practice, you get really big files pretty quickly and unless you are planning on blowing things up all the time, scanning at those kind of resolutions is so much higher than what your screen or printer will do. So most of the time there isn't a point in it since you can't display it at that resolution anyhow.

Also the bigger files need that much RAM too, so a few big files can slow things down.

Answer 2

Umm I would probably go with the higher resolution model.