What’s the difference between PPI and DPI and why are they always mentioned on creative software? Find out the distinct characteristics of each setting with this handy guide.
Cover image via YamabikaY.
You may have noticed the acronyms DPI and PPI thrown around quite a bit on creative platforms. So, what do they truly mean? These terms both define the general resolution of an image in separate realms – digital versus print. Many use DPI and PPI interchangeably, but there are differences between the two. Let’s clear the air and go over what each acronym means.
PPI (Pixels Per Inch)
If you’re a designer or photographer, you have most likely seen PPI used when exporting or designing for web. PPI, or pixels per inch, deals with pixel resolution and is usually reserved for screen and digital image formats. Only raster images can be measured in PPI; vector images are infinitely scalable and do not rely on pixels. Pixels are “picture elements” – small squares of color that become more visible when zoomed in on a raster image.
Image via Bro Studio.
An image with a higher PPI tends to be of higher quality due to its greater pixel density. The individual pixels in a 300 PPI image are drastically smaller than in a 72 PPI image. Smaller pixels allow for a smoother blend of color and shape. As soon as you enlarge an image, you expand the size of the pixels, the culprit of those unsightly jagged edges.
Notice the differences between the same leaf image at incremental pixels per inches. Even when expanded to large proportions, the 300 PPI image appears more crisp than the 72 PPI image. The smaller the pixels, the higher the PPI, and the better the quality.
In any image editing program, like Adobe Photoshop, it’s important to understand the distinction between resizing and resampling an image. They sound similar, but each achieves a different result. Navigate to Image > Image Size in the Photoshop program to adjust the size and dimensions.
In Adobe Photoshop, you can see how decreasing the pixel density of this leaf image increases the height and width in inches. Resizing the image does not affect the dimensions or size, but rather the print output. An image set at 300 PPI will be printed at a smaller size than the same image at 72 PPI.
Let’s say an image is measured at 4 by 6 inches at 300 PPI. When decreasing the pixel density to 72 PPI on the Image Size panel, the print output will be larger, even when the image dimensions are the same. This is because Photoshop is measuring the width and height in inches, which is reserved for printing purposes.
Resampling an image refers to adjusting the amount of pixels in an image. When resampling is checked, notice how the values change. As the resolution in PPI decreases, the image size and dimensions decrease with it. Notice how the Image Size panel switches over to measuring in pixels, a measurement reserved for online and web images. At 300 PPI, this image starts out at 5000 pixels by 3407 pixels, but when resampled to 72 PPI the altered image will be smaller at 1200 pixels by 818 pixels.
Resampling is ideal for decreasing the size or dimensions for online upload constraints. Avoid increasing the resolution when resampling; Photoshop will struggle to add pixels to a lower resolution image, resulting in fuzzy edges. This same effect is similar to expanding a low quality image.
PPI Print Standards
When setting an online image to be printed, it’s best to use the correct pixels per inch. Export your design at 150 or 300 PPI for professional quality standards. Setting an image at a high pixel density will prepare the image to be printed at a better quality in DPI. Leave 72 PPI for web images when there are strict file size requirements.
DPI (Dots Per Inch)
DPI refers to the physical dots of ink per inch on a printed or scanned image. Printers do not display color in pixels, but rather in layered dots consisting of cyan, magenta, yellow, and black (CMYK). For instance, A 300 DPI image displays 90,000 separate dots of pigment inside one inch. If you scan a printed image and zoom way in, you can visibly see those CMYK dots.
Many confuse DPI for PPI; dots per inch refers to the print output, while pixels per inch represents the data input of the image.
Image via maurobeltran.
PPI is easy to manipulate in an image editing program; DPI is a whole different story. Each model and style of printer produces its own unique DPI based on its printer settings. Inkjet printers produce a resolution around 300 to 720 DPI, while a laser printer produces images from 600 to around 2,400 DPI. As long as the DPI of the printer matches or exceeds the professional PPI, the image will print at a high quality. The greater the DPI, the smoother and crisper the printed image will be, to a certain degree. A 300 DPI image already packs 90,000 dots of color; going above 300 DPI will not change the output too much.
Now you’re a DPI vs. PPI master! Using the correct specs can improve your creative workflow and image quality. Remember, PPI is the data input of an image and the DPI is the printed output of that image.
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