At Nostalgic Media, we get more questions about scanning, resolution and file formats than anything else. Hopefully, we can cut through some of the misinformation. We'll keep it simple:
Scanning Resolution: DPI & PPI Crash Course
DPI = Dots (of ink) Per Inch. Use DPI when you're printing
PPI = Pixels Per Inch. Use PPI with monitors and TVs.
Tips On Photo Scanning
If you never plan to make enlargements to your scans, stick with 300 DPI
If you expect to enlarge or crop your images, scan your original photos at 600 DPI
Researchers at the University of California determined that the average person viewing an image at a distance of 20 inches will detect about 170 dpi. Your ink jet printer may be printing from 120 to 240 dpi. Prints from a one-hour lab are about 220 to 240 dpi. How about a slick fashion or travel magazine? Those pictures can be about 180 to 250 dpi. A billboard viewed from a quarter mile looks good at 15 dpi. As distance increases, resolution can decrease.
Printed Media = DPI | Resolution |
Photo from a one-hour lab |
200 - 260 dpi |
Consumer ink jet printer |
150 - 280 dpi |
Glossy color magazine |
180 - 240 dpi |
Newspaper |
160 - 200 dpi |
Large billboard |
12 - 30 dpi |
Scanned Media | 300 DPI - Excellent | 200 DPI - Good | 150 DPI - Acceptable |
4x6 photo: 300 dpi |
4"x6" |
7"x10" |
10"x14" |
4x6 photo: 600 dpi |
8"x12" |
13"x20" |
17"x26" |
8x10 photo: 600 dpi |
16"x20" |
24"x36" |
32"x40" |
35mm slide: 2000 dpi |
7"x10" |
10"x15" |
13"x20" |
35mm slide: 4000 dpi |
14"x21" |
20"x30" |
26"x40" |
6x6 negative: 3000 dpi |
20"x20" |
30"x30" |
40"x40" |
4x5 negative: 2000 dpi |
26"x33" |
40"x50" |
52"x65" |
PPI = Pixels Per Inch. Use PPI with monitors and Tvs
A 21-inch monitor is about 105 ppi and
looks sharp at 20 inches.
A 40-inch HDTV is about 48ppi.
It looks sharp when viewed at 10 feet.
Digital Media = PPI | Dimension (pixels) | Resolution |
40-inch HDTV |
1920x1080 |
48 ppi |
24-inch monitor |
1920x1080 |
92 ppi |
21-inch monitor |
1920x1080 |
105 ppi |
Laptop: 15" monitor |
1920x1080 |
141 ppi |
iPhone: 4.7" screen |
1136x640 |
326 ppi |