How To Resize Your Images For Amazing Prints
Updated: Oct 5, 2020
Many photographers try to print their image without resizing them to the print size desired first. This is a big mistake. When you don’t resize your image, then the pixels get squeezed and stretched like Gumby. On a small print you may not notice but as the prints get larger, it can get ugly.
Before I provide a simple step by step procedure, it is worth going over some theory on print size first. For the purpose of this blog, I am going to need to make some assumptions first. I will assume a 300pdi image at its native resolution (from RAW image file @ 300 ppi at the original size). Let’s assume 6000 ppi x 4000 ppi @ 300 ppi (24MP).
To produce stellar looking prints, you will need your output file to be 300 ppi. If your image originated from a RAW image file, then 300 dpi will be the default resolution. An image width of 6000 ppi will provide an actual print width of 20 inches. It is a simple calculation: 6000 ppi / 300 ppi = 20 inches. A 6000 ppi x 4000 ppi print will be 20 inches x 13.333 inches at 300 ppi
Tip: To find out what print size you can make based on the image pixels per inch (ppi) width simply divide the width in pixels by the ppi (resolution) of your image. For example, if your image is 4000 ppi wide and your image has a resolution of 200 ppi, then 4000 / 200 = 20 inches wide. At 300 dpi, your image will be 13.333 inches wide. At 72 ppi, your image will be 55.555 inches wide.
If you want to print your image at its native size, then no resizing is needed but if you send your prints out to a printing company, then you will need to specify what size print you would like and that it matches the resolution. This is why you need to know how to calculate print width based on your image resolution. Problems arise when there is a mismatch between print size and resolution.
If you want to print bigger than the native size then you will need to resize the image. If you want to print smaller than the native size, it probably won’t be too much of a problem as the pixel “squeeze” shouldn’t be noticeable but I recommend you always resize your images to match the print size you desire. This will ensure your image always prints out to the highest possible quality.
A quick note on resolution. Maximum image quality can only be achieved with a 300 ppi image resolution. As the resolution decreases, the quality decreases. Anything above 300 ppi will not produce a higher quality print. The human eye cannot discern anything higher than 300 ppi.
But you might be asking…. if the resolution is lower, then won’t my print be larger based on pixel width divided by image ppi? Yes, you are correct. Stand close to the image and, trust me, you will notice the drop in quality. But if you stand further back, the image will appear to look fine. The lower the resolution, the further back you will need to stand in order to perceive a higher image quality. The bigger the image, the further you will need to stand away from the print to perceive image quality. If you want to perceive maximum image quality at a comfortable distance from the image, then 300 ppi is the resolution you should strive for.
To resize your image in Photoshop:
The keyboard shortcut is > Crtl-Alt-I or at the drop-down menu click > Image >Image size.
Before proceeding any further make sure that you have Resample & Automatic selected. If you do not use Adobe Photoshop, then there will a dialog box that is similar and you should be able to make the same adjustments.
1- The first dialog box shows my native image size and ppi. In this case 6000 ppi x 4000 ppi at a resolution of 300 ppi.
2- In the second dialog box, change the units from pixels to inches. Notice the original size (6000x4000) remains the same. At this point nothing has changed except the units of measurement. Since we are selecting what size image to resize to the units need to be in inches.
3- In the third dialog box, change the image size to what you desire. In this case I have selected 48 inches. Notice the image height automatically changes to 32 inches. But also notice the image size increased from 6000 x 4000 to 14400 ppi x 9600 ppi. 14400 / 300 = 48 inches. Also, notice the Fit To box changes from Original to Custom. Photoshop will automatically “fill in” pixels based on built-in smart technology to increase the size of the image to allow for 300 ppi resolution for the new width. Once you are done click OK.
4- In the fourth dialog box, change the image size to what you desire. In this case I have selected 10 inches. Notice the height automatically changes to 6.667 inches and the image size has decreased to 3000 x 2000. 3000 / 300 = 10 inches. Photoshop will automatically “delete” pixels based on built-in smart technology to reduce the size of the image to allow for 300 ppi resolution for the new width. Once you are done click OK.
Do not save the original image. Once you are done then do a “save as” in the format you would like (tiff, jpeg, etc) to use for printing and you are done.
Remember, the print size MUST match the resolution. If you try to print a 6000 x4000 @ 300 ppi image at anything other than 20 inches x 13.333 inches using 300 ppi, then you will sacrifice print quality. You must always resize your image to suit the final print size using the image size dialog box.
Also, there is a limit to how much you can enlarge an image and retain quality. A 6000 x 4000 @ 300 ppi image can easily be sized up to about 48 inches with no loss in apparent image quality. To get a reasonably accurate view of what your image will look at actual size, zoom your image to 1:1 on your monitor. In Photoshop click Ctrl R to turn on the ruler guides and zoom in until you can measure 1 inch on the screen. Use a hand ruler to confirm. Typically, the image zoom will be about 36% on a 27 inch monitor to display as 1:1. Adjust the zoom as needed based on your actual image size / monitor size.
Important - Zooming to 100% is NOT 1:1.
-Importing RAW files into Adobe Photoshop
-Using Adobe Camera Raw
-Adding grain to an image
-sRGB vs Adobe RGB
- and more…..