Optical Resolution – An Important Note
For nearly any type of scanner you run across, it’s very important to check the “maximum optical resolution” of the scanner. Why? Well, you’ll often see marketing materials that show ‘interpolated’ resolution – which is actually just software attempting to output a larger image from less data.
The problem is that the software is unable to digitize a quality (clear) image.
So, when you’re considering optical resolution, make sure you look for the “vertical” or “horizontal” resolution. If you see optical resolution “below” either of these two numbers, then the software is using interpolation techniques.
Scanner Tip of the Day:
So how do you determine how much resolution is actually needed? Simple. It’s based on the job you intend to do. There’s no set rules, but you can think about it this way:
- If you’re planning to use it on a computer screen, you’ll need a resolution of roughly 75 DPI (very low res – a minimum for most jobs, but allows you to load/see the image quickly).
- If you’re image is being sent to the printer, you’ll need a minimum of 300 DPI for color and 600 DIP for black and white.
When using these guidelines, we’re assuming you want your final image to be roughly the same size as your original image.
Just remember, if you want to enlarge your image, you’ll need higher resolutions.
For enlargements, better resolution is needed so that the final image maintains the required dpi after the image is enlarged. For instance, to print a 4″x5″ photo at the size of a full sheet (8″x10″), the 8″x10″ image will need (300 x 10) 3000 pixels down the long side. That turns into (3000 / 5) 600 dpi for the original scan.