Resolution for Printing
Everything you need to know about image resolution and how it affects printing outcomes
What Is Image Resolution?
Resolution in printing refers to the number of pixels that will be printed per inch of paper, not just the total pixels in the digital file. Proper resolution is essential for achieving clear and accurate print results.
DPI (Dots Per Inch) = Pixels ÷ Inches
Image resolution determines the level of detail in a digital image and is crucial for printing. Unlike on-screen viewing, where an image may look sharp, low-resolution images can appear fuzzy or pixelated in print.
Digital images are made of tiny dots called pixels. The more pixels per inch, the more detailed the image. For printing, you must ensure there are enough pixels for the intended print size—the larger the print, the higher the resolution required.
High and Low Resolution
For professional offset printing, 300 dpi is the standard resolution. Images below this, such as 72 dpi, are considered low resolution and will print poorly. For example, an image with 300 pixels per inch will display far more detail than one with only 72 pixels per inch.
How Do You Check Your Image's Resolution?
Check the resolution by calculating
You can determine your image’s resolution by calculating it based on the pixel dimensions and the intended print size. Here’s how:
1. Check the pixel dimensions:
- Right-click the image file and select Properties (Windows) or Get Info (Mac).
- In the Details tab, note the Width and Height in pixels.
- Ignore the “Horizontal” and “Vertical” resolution values—they usually do not reflect the actual resolution you need for printing.
2. Calculate the print resolution:
Decide the final print size, use the formula:
Width resolution (dpi) = Width in pixels ÷ Print width (in inches)
Height resolution (dpi) = Height in pixels ÷ Print height (in inches)
3. Check against standards:
- For high-quality offset printing, aim for 300 dpi.
- A minimum of 250 dpi may be acceptable for less critical prints.
Check the resolution in Photoshop
1. Open the image in Photoshop. Click on Image > Image Size.
2. Uncheck the Resample, then fill in the size you want to print, and check the resolution.
Check the resolution in InDesign
Place the image in your design. Adjust to the desired size. Read the Effective PPI in the Links panel.
Can I Increase the Resolution in Photoshop?
It’s possible to try to increase your image resolution in Photoshop by resampling. “Desampling” will decrease the amount of data in your image and “upsampling” will increase it. Unfortunately, the results in print won’t be good because the original image resolution remains unchanged. For that reason, we don’t recommend it. It’s always better to start out with a high-quality, high-resolution image.
A Word of Warning About Grabbing Images from Websites
Beside the importance of using images legally and not breaching copyright laws, images found on the web—unless they are high-quality licensed stock photos—are usually very low resolution and useless for printing.
