Quality and image resolution are two essential things to consider when it comes to editing photos and creative assets. If your images are going to be printed, more specifically, you’ll also need to understand how DPI can affect your project.
Whether you’re new to photography and design or just revising your knowledge, read on to learn what DPI is and how it applies to your digital images.
DPI stands for Dots per Inch, referring to the number of ink droplets a printer will produce per inch while printing an image. The more dots of ink per inch the picture has, the more detail you will see when printed.
DPI is used for printer resolution, to indicate the clarity and detail of an image on paper. It’s an important measurement for photographers and designers, as it will determine the quality of a printed asset – whether for a poster, a brochure or a glossy magazine.
If an image has a resolution of 300 DPI, this means that every inch contains 300 dots of ink. Photographers and graphic designers typically use 300 DPI as a benchmark for printing high-quality images. However, larger images may require an even higher resolution.
PPI (Pixels per Inch) refers to the number of pixels that make up every inch of a digital image. It’s used to describe image resolution on a screen, rather than in print. DPI, meanwhile, refers to number of dots in every inch and is generally used for print purposes.
PPI and DPI do however serve very similar purposes, indicating the overall resolution of an asset. This is also why PPI can be easily confused with DPI resolution.
Finding the DPI resolution of an image is straightforward when you use Adobe Photoshop. Photoshop measures resolution in PPI, but its ratio of PPI to DPI is 1:1, so you can still find out what the DPI of an image is.
Just follow these simple steps:
You can also find the DPI resolution of an image using Adobe InDesign. InDesign is professional page design software, perfect for editing and designing posters, magazines, prints and banners.
InDesign uses two terms to refer to resolution — Actual PPI and Effective PPI.
Actual PPI is the resolution of the image while at 100% of its original size, meaning when the image is at its original dimensions without being resized.
When you enlarge an image, the existing pixels are stretched to accommodate the new size. This is where Effective PPI comes in. This refers to the resolution of the image based on how it is placed on the InDesign page — showing how the final product would look if it was enlarged or reduced in size.
So, for instance, if you wanted to print an image at 300 DPI, you would need to make sure the image has an Effective PPI of 300.
Here are step-by-step instructions of how to do this on InDesign:
You can also find the DPI of an image on Windows. Just follow these steps:
To find the DPI resolution of an image on Mac, you need to use Preview, the default app.
The ‘right’ DPI will vary, depending on your desired result and purpose.
When coming to the decision of what DPI to use, consider the following:
If the final product is a photograph, flyer or business document, the general benchmark to achieve a high-quality print is 300 DPI.
If you’re making a poster, depending on its size and distance from the viewer, you’ll need at least 100 DPI. You can also use lower DPIs for smaller images or test images if you like. This is something you can play around with on Photoshop, Illustrator and InDesign to find the best result for you.
For more professional magazine images, or exhibition-quality artwork, you may need 600 DPI or even higher to achieve pristine-quality results.
If you’re working for a client or organisation and you’re unsure what to use, it’s always best to confirm the exact DPI resolution they’re looking for to meet expectations.
It’s easy to change and customise DPI resolution using Photoshop. Just follow these instructions:
If you don’t want to change the pixel dimensions of your image, make sure to deselect Resample while you use these tools. Resampling can add additional pixels to your image artificially, which can degrade image quality and make it look worse than before.
The best resolution for your project depends on its purpose. For print resolution, 72 DPI is generally considered too low, and may be better suited to small icons that do not need to be high-quality. 300 DPI meanwhile is the printing standard for photos and professional brochures, which need to look crisp and detailed.
The conversion of PPI to DPI is usually 1:1. This means if an image is 10 inches in width by 10 inches in height at 300 DPI, your pixel dimensions need to be 3000px x 3000px. In other words, you need to multiply the print size (width and height in inches) by 300 to find the right pixel dimensions (e.g. 3000px x 3000px) to provide 300 DPI.
Yes, most industries would describe 600 DPI as high-resolution. If an image has a resolution of 600 DPI, the printer will produce twice the standard number of dots per inch. As the droplets of ink will be very tightly bunched together, this gives a much smoother, more detailed image which can be made larger without sacrificing quality.