Have you had cases when someone looks at a photo at 100 percent and says it looks bad, but when you check it yourself, it's just fine? Is it possible that both are correct?
History of Zoom
In the past, pieces of art were viewed in their natural habitat: their tangible versions. Whether it's a beautiful ring, a gorgeous painting, an impressive wood carving, or a magnificent old building, it always looks good when you normally engage with it. By "normally," I mean the common situations when you happen to see such an artifact. If you go closer to a building and look at the details of its walls from 10 inches, you will see lots of imperfections. The same goes if you look closely at a big painting. The less the imperfections at closer levels, the higher the overall visual quality of the object is. Usually, even if imperfections seem a lot from a small viewing distance, they rarely affect the image and impression.
There are lots of similarities with digital content. Normally, you look at them at a certain distance, and even if you zoom in and see imperfections, they may not be noticeable otherwise. We, as visual craftsmen (as well as some sophisticated clients), tend to zoom in on graphics to see how good the detail is. Many times, people change their overall opinion about a visual piece of art based on the zoomed version, which is a different story. In order to be fair, we usually zoom at 100 percent. There is an assumption that 100-percent zoom is fine, while more is too much of a test. How is it possible to have different and at the same time, correct quality conclusions when zooming 100 percent of the same image?
How Does a 100-Percent Zoom Work?
Not all zooms are the same. If we are talking about looking closely at a physical object with our own eyes, our "zoom levels" will be identical, but with digital content, the zoom function is stolen by the media we're viewing the graphic with, the displays. When you tell an application to show a 100-percent zoom of visual content, it will base the final result off of the number of pixels on your screen. As screens differ in sizes, the functionality that shows you a 100-percent zoom representation will have different results on different devices.
In the following example, there is an image of size 3,888 by 2,592 pixels. It's a shot from the days when 10 megapixels was a normal image size. Let's have a laptop with a screen resolution of 1,024 by 768 and a 5K monitor with a resolution of 5,120 by 2,880 pixels. On both displays, we open the image in Photoshop or similar software, and we zoom in at 100 percent. The results will be quite different.
The smaller screen will show the following:
Zooming at 100 percent was a thing when most displays were similar. With today's diversity, 100-percent zoom is only a number that has nothing to do with the quality judgment of a visual. If you want to deliver quality results, simulate the view of the final media your work will be displayed on. The fact something looks detailed on a small screen doesn't mean it will be as detailed or good on a large screen for the reasons presented above or vice versa.
Another Possible Conclusion
You don't have enough money for a 40-megapixel stills camera or an 8K video camera? Do not worry. Just tell your clients to get bigger displays and higher-density mobile devices, and your visuals will look great at 100 percent. No full screen allowed.