View Full Version : virtual memory

10-05-2002, 05:04 PM
I was scanning a picture at 750 dpi resolution at scanning
and output was 600 dpi. It took a hell of a long time nearly 40 minutes- my PC is Duron 950 CPU & has got 256 MB memory & runs Win XP HE.

After that when I was trying to put that picture on the desktop, the system froze.
Then a message came on the right bottom saying that the system has low 'virtual memory' and it was doing something on it....

Could someone explain to me why with a resonably good system with high memory etc. was doing like that?

This is purely out of interest to learn.


10-05-2002, 05:13 PM
It took so long because the file was enormous. Generally you dont need to scan at that resolution, you will only see a tiny portion of it on your screen. 75dpi or 100 dpi is adequate unless you really need to scan something with fine detail.

Have a look at this scantips site:

10-05-2002, 06:24 PM
Try the arithmetic. 750 pixels/inch means 750X750 for each 1 inch square. If you are using colour, that will be 3 bytes per pixel. So a 6' x 4' picture would be about a 40.5MB file. Your 256 MB of ram holds the operating system, and the scanning software, and any other programmes you have started up ...

The scanning programme will probably use a couple of copies of the scan too --- to allow for manipulation of the image.

High resolution uses LOTS of memory. If it doesn't exist in real form,, it is 'made' as virtual memory on the hard disk. That's a LOT slower.

11-05-2002, 08:29 AM
Terry, thanks for your help.
It was quite revealing and informative.

Thanks mate

12-05-2002, 06:43 PM
Dear Graham

What then should be the highest & the lowest virtual memory settings that I should make in my PC.

Please tell me.