Digital image resolution is measured by PPI (pixels per inch). What is PPI? A pixel is the smallest unit of a digital image that can be displayed on a screen. One pixel of the digital image will appear as one pixel on your computer screen, phone, TV or other electronic digital viewing device. The PPI of a digital image can range anywhere from 1 pixel to any number. The PPI of an electronic digital viewing device is a set number and does not fluctuate. 300ppi is the recommended digital image resolution size for printing a high quality photo at 100% (the human eye cannot see any difference above 300ppi). So, if you view a 300ppi digital image on a 100ppi computer screen, it will appear 3 times larger than the print size. Screen size and display settings will also affect the viewing size of the image, especially on a phone. Please keep all of that in mind while viewing the images below. Read more information at FAQ.
Photo Print Scanned at 75ppi - Normal Screen Size
This is a 75ppi scan of a printed amateur photo. The original photo size is 3 1/2 inches by 4 7/8 inches. Below is the normal screen size (the screen size varies depending on the device you are viewing it on and the device settings). This is a good size for social media. To print this at high quality, you would need to change the digital resolution to 300ppi and then the printed photo size would be 0.873 inches by 1.207. A 150ppi scan of the same photo would appear on screen twice the size of the 75ppi image and the printed photo size would be 1.747 inches by 2.42 inches.
Photo Print Scanned at 300ppi
We scanned the photo again, but this time at 300ppi. The screen size would be 4 times the size of the 75ppi image above (not shown). It's difficult to simulate on a screen, but the image below is an approximation of what the photo's resolution and size would look like if printed at 300ppi and the size was 3 1/2" x 4 7/8" (300ppi is the recommended digital resolution for printing high quality photographs). The bottom two photos are zoomed in on the area inside the red rectangle.
75ppi vs 150ppi vs 300ppi Photo Print Scan Comparison
The 3 photos below show the visual difference in resolution (PPI). The original printed photo was scanned at 75ppi, 150ppi and 300ppi. After that, we increased the PPI of the 75ppi and 150ppi scanned images to 300ppi and enlarged them to 3 1/2" x 4 7/8" (the 300ppi scanned image was already 3 1/2" x 4 7/8"). Below is an approximation of what the printed photos would look like.
If you want to view the animated version, click HERE.
If you have a small screen, you may need to zoom in to see the difference.
300ppi vs 600ppi Photo Print Scan Comparison
The 2 photos below show the visual difference in resolution (PPI). In this scenario, a person wanted a close up photo of the dog by itself. For this example, the original photo print was scanned at 300ppi and 600ppi. After that, both photos were zoomed in on the dog with a photo size of 3 1/2" x 4 7/8" at 300ppi. Below is an approximation of what the printed photos would look like.
If you want to view the animated version, click HERE.
If you have a small screen, you may need to zoom in to see the difference.