I have a flat bed scanner which I use to scan photos (6x4") for later printing to a larger size. I scan these at 300 dpi but now I want to scan the same photos to e-mail to friends. Can anyone suggest a suitable dpi for this. I was thinking of 100 or 150 dpi but would this give a good enough image on a pc screen? Thanks for any suggestions.
Hi REDYELBLU. It depends what your friends will be using the pictures for. If they want to view the pictures on their computer monitor, then it's a good idea to make the picture suit the monitor resolution. If they want to print the pictures, then you need to consider the size and quality of the print they want. A jpg picture of 600 x 480 pixels at moderate jpg quality is only about 20k, and so will email fairly quickly, but wouldn't make a very good 6 x 4 inch print. I think a 1024 x 768 pixel picture at moderate jpg compression is a good compromise for file size and print quality, and matches what I find to be a good setting on a 17 inch crt monitor. You can scan at high resolution and use a graphics utility such as the superb free Irfanview (click here) to resample the picture to a more convenient size.
Just resize using Irfan View. I find a quality setting of 50 is fine for photographs. 1024x768 should be about 125K
To get the best results, crop with a 4:3 aspect ratio before resizing. Your 6" x 4" photos scanned at 300 dpi would be 1800 x 1200 pixels, so for optimal display on monitors you could crop to 1600 x 1200 before resizing to 800 x 600 or 1024 x 768.
Could anyone give me very basic information about how to go about scanning in a 3 by 5 photo in order to print in out at A4 size? I have a canon LiDE30 scanner, a basic HP deskjet printer and only the canon software that came with the scanner.
Hi Carafaraday, the replies given above also apply to scanning for large prints. Make sure you scan with sufficient resolution. Generally 150dpi is considered about right for printing, so for an A4 print you need about 1700 pixels across the long dimension. For a 5 inch wide photo this will need the scanner resolution to be at least 350 dpi. You can then use your picture manipulation software to resample this to the size you want at a resolution of 150dpi. If you want to fill the A4 sheet, you will have to lose some of the 5 inch picture dimension because the picture width to height ratio is different from the paper.