Answering the High/Low Res Question

Have you ever been disappointed with the quality of your artwork in print? Even though you followed all the guidelines and specifications, it still looks bad. This post aims to help you understand the difference between High and Low-Resolution image settings so that you can submit the best images of your art in the future.

Please note that I come from a print background, so I refer to dots per inch (dpi) instead of pixels per inch (ppi). The only difference between the two is that pixels are square-shaped in digital applications, while dots are used in offset printing and round.

© Nancy Murty | Summer Meadow | 12×8 in | oil on linen | sold

When it’s best to use Low and High Res images and the advantages of both:

Low-Res Images (72dpi) are recommended for digital use. The file size is smaller, allowing faster loading times. Additionally, the file’s low resolution means it does not enlarge or print well, which can help limit the unauthorized use of your image. Low-Res images are ideal for websites, blog posts, social media, and emails/newsletters.

High-Res Images (300dpi or better) should only be sent when requested and to trusted destinations. High Res images are suitable for magazines/publications, prints/reproductions, and print promotional items such as postcards, business cards, posters, exhibit catalogs.

Understanding the Conversion Process

Going from High-Res to Low-Res

Converting a high-resolution image to a low-resolution one is a simple process that can be done with just a few clicks of a mouse or taps on a screen. When you lower the resolution, the only noticeable change is that the image appears smaller on your computer screen, although you may not notice any difference if you’re using a tablet or smartphone.

Enlarged view of the same area of a high res and low res image side by side Low res image is pixelated.
In this enlarged view of the same area, notice the square pixels in the Low Res 72dpi image.

Even though it only takes a few clicks to change the resolution of an image, the photo program you’re using actually does some complicated work behind the scenes. It uses an algorithm to interpret the colors of multiple pixels and combine them into a single pixel. When you reduce the resolution from 300 pixels per inch to 72 pixels per inch, the program combines a little over 16 pixels in a 4×4 arrangement to create a single pixel.

converting 300 pixels per inch to 72 ppi

is the same as

combining 16 (4×4) pixels into 1 pixel

You Can’t Go Back from Low-Res to High-Res!

You may be thinking — Yes, I can! My photo program does it without any problem! But, no, it doesn’t REALLY DO IT. Not with any kind of print quality! It’s a fabricated high-resolution image and will print looking blurry or out of focus. Look at the image below.

can't convert an image from low res to high res
A 72 dpi image is saved as a 300 dpi image. Notice how it looks blurry and out of focus.

Earlier, we discussed the process of converting several pixels into one pixel of color. However, when converting a Low-Res image to High-Res, the photo editing program must reverse the process, creating additional pixels and interpolating color from surrounding pixels to make an approximation. To better understand this process, let’s examine what happens at the pixel level within the program’s algorithm.

Compare how the photo editing software converted the color to pixels in each image
Compare how the photo editing software converted the color to pixels in each image.

In the center image above, you may notice a bright yellow square in the upper right quadrant, which is the most prominent. If you compare the same area in each image above, you’ll see that multiple pixels in the 300 dpi image became one pixel in the center image. And then, in the image on the right, one pixel became several pixels. Unfortunately, the photo program can’t create details that aren’t present in the low-resolution (72 dpi) version.

As a result, images converted from Low-Res to High-Res often appear blurry, out of focus, and distorted. Additionally, the colors may shift, losing the subtleties that are crucial when reproducing artwork. These differences become apparent when you compare the original and edited images side by side.

You may think that your printer can create high-resolution images, but the fact remains that it is still a fabricated high-resolution image. Unfortunately, you can’t create details that don’t exist. I’ll repeat it:

You can’t convert a low-resolution file back to high-resolution and have it reproduce the beauty and intricacy that your artwork deserves!

Don’t be disheartened if the alluring promises of photo editing software have deceived you. Now that you know the truth, you can ensure that your artwork always looks its best in publications. However, this is only one aspect of the process. Adjusting the RGB and CMYK settings and using the highest-resolution image possible is also crucial. Keep in mind that your phone’s camera may not always provide the best quality image.

I hope this clarifies the difference between high- and low-resolution images and explains why it’s not possible to increase an image’s resolution after it has been created without losing quality.

nancy

Other Helpful Resources:

How Converting Images from RGB to CMYK Affects the Colors
Get the Best High-Res Images of Your Artwork

Video on using the color chart for photographers

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