When scanning most documents, 300dpi is an average setting that would work adequately for most work. Note that dpi stands for dots per inch. Here are some other considerations and factors that might require a different scanning resolution.
- Big Fonts. If you’re scanning a document that uses large fonts, then you can scan at a lower resolution such as 200 or 150.
- Fine Text. If you’re scanning a document that has very small fonts, such as a legal contract or terms and conditions, you may want to use 600 dpi to ensure the text can be easily enlarged and also for better optical character recognition (OCR).
- Quality. Consider the ultimate use for the scanned image. If you’re planning to reprint something later, you may want a higher resolution. If you are scanning a document that’s going to be made into a PDF for public viewing, you’ll want to use 300dpi or higher for the best visual quality. Keep in mind that it’s always best to use an original digital file rather than a scanned image of a printed document.
- Quantity. If you have a lot of pages and materials to scan, and quality isn’t an issue, then using a lower dpi will speed up the process.
- Slides. If you are scanning photography slides, you will want a much higher resolution. This is because the slide itself is quite small, but you’ll likely want to be viewing it on a computer display or printing it to a larger format. In order to have a quality resolution image later, you’ll want to scan at a higher resolution such as 1,200 dpi or even 3,000 dpi. For slide or negative scanning, you would need a special photography scanner with a backlighting capability.
- Small Images. Smaller photos of about 2 inches by 2 inches should be scanned at higher resolutions so they can be enlarged without loss of quality.
- Speed. Using a lower dpi setting will typically speed up the scanning process. If you have a huge document that you want to get scanned, try using the lowest resolution setting that produces the results you need. Do this by running a test scan.
Scanner Model Types
- Double-Sided. Some scanners with page feeders can flip a page over and scan the back, while other models can scan both sides of the page at one time which is much faster.
- Flatbed. When scanning a book or odd shaped documents, it helps to have a flatbed scanner.
- Legal. When buying multi-purpose printers, you’ll notice that some have a letter-sized flatbed scanning capability. Others will be slightly larger in size to accommodate a legal-size (8.5″ x 14″) flatbed scanning capability. This is very helpful if scanning large receipts.
- Receipt. Some scanners are designed for receipts. They are usually smaller and have a feeding mechanism. Rather than scanning a large flatbed area, these pull the receipt through and scan only the image area needed which could possibly save time when scanning small pieces of paper.
Color or Black and White
Use color scanning only when necessary. Scanning in grayscale or black and white should be faster and will result in smaller file sizes. If you have black text on a colored background, for example, you may find that black and white or grayscale works better. With receipts and other documents that are hard to read, experiment to find which scanning mode works best.
Page Size Setting
If you’re scanning standard size 8.5″ by 11″ pages on a flatbed scanner, you can set the page size accordingly. If you’re scanning smaller pieces of paper, then scanning at 8.5″ x 11″ will scan more of the scanner bed than necessary. This takes more time. Experiment with using the A5 and A6 sizes. This should speed up scanning because the unit won’t need to move across the full scanner bed.
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