Did you ever need to enlarge a low-resolution image? Say that kitty photo that you downloaded from the web and wanted to use as wallpaper. Or did you try to print those lovely child pictures of yours that your parents took ages ago with that old camera? Or, yes, the one and only product picture your client had to put on the website?
A few years ago, there wasn’t much you could do about it without dedicated software and relevant skills or hiring a professional. Because if you just make your picture significantly bigger, it will end up looking like a Minecraft screenshot or a Cubist masterpiece. The reason for this is the low resolution of the source image. However, today there are plenty of apps and online services that let you enhance resolution and don’t turn your photo into a cubical mess.
So, let’s see how you can upscale digital imagery. But, first, we need to understand why it’s not that easy to turn low-resolution images into high-resolution ones.
A digital raster image consists of pixels. The more pixels, the higher the resolution.
Here’s a low-resolution image: 200 x 300 pixels, or 60,000 pixels total.
Here’s a higher resolution image: 669 x 1002 pixels, or 670,338 pixels total.
In small sizes, they look almost the same:
But when you enlarge them, you immediately see the difference:
It happens because when you simply resize an image, the number of pixels doesn’t change. You just make every pixel larger. At some point, pixels become so big that they no longer look like dots. Instead, they turn into small cubes because they’re actually squares, not circles.
The high-resolution images have more pixels. So even if we increase each of them by a mere 5%, we already have a noticeable growth in image size without visible loss of quality. On the other hand, low-resolution images have a small number of pixels to start with, so every pixel needs to become noticeably larger to occupy a bigger space.
Thus, you need to add more pixels to a low-res picture somehow if you want to increase the resolution of a low-res image while maintaining quality. The process of increasing the number of pixels in an image is called upscaling or upsampling. And there are four different ways to make a digital image bigger.
There are many different tools and services to increase image resolution, but it’s tough to choose the best one. So, before digging into specific options, let’s look at two methods.
The manual method can provide you with high-quality results with almost no limits on the size of a picture. But it requires skills and time, or time and money if you hire a professional.
Sure, you can resize pictures without it in any essential graphic software, like Paint 3D, and even in office apps, MS Word for one. Check the video to see such an unsophisticated approach to image enlargement.
The online image enhancement method has its pros and cons, too. These tools are easy to use, fast, and often free. Some of them can even handle multiple images at once. However, as a rule, they have limitations to the maximum size of the output, but it’s not a problem unless you’re going to put your image on a billboard.
Different methods are suitable for different situations, and you can mix them for the best result. We’ve tested these options of increasing resolution in detail and compared them by the following key points:
Given its plenty of functions, there are several ways you can go about upscaling your images in Photoshop. We’ll try the two most popular algorithms: Bicubic Smoother and Preserve Details 2.0.
Here’s how to upscale your image using Photoshop’s Bicubic Smoother:
We don’t see any pixelation, but the image looks blurry when zoomed in.
Here’s how to upscale your image using Photoshop’s Preserve Details 2.0:
Here’s what we’ve got:
Well, the result of the Preserved 2.0 looks better than the output of the Bicubic Smoother. At least, with this image. We’ve got smoother contours and fewer artifacts.
Why GIMP? Today there are a lot of other photo editing apps, and many of them are free. We took one of these for the test, the GIMP (GNU Image Manipulation Program). It’s a free and open-source image editor for raster graphics. The interface and functionality are similar to Photoshop.
GIMP uses cubic (bicubic) interpolation and two specific methods named “NoHalo” and “LoHalo”. These are GEGL methods, and halo is an artifact created by interpolation.
Here’s how to upscale your image using GIMP:
LoHalo and Cubic are about the same level, while the LoHalo output is a bit sharper.
NoHalo method has shown the best result in this test: outlines are clear, noise and artifacts are hardly noticeable.
Now, let’s compare the results of GIMP (NoHalo) and Photoshop (Preserved Details 2.0).
The Photoshop output looks sharper. Preserve Details 2.0 has also handled shadows and complex textures better.
If you are not sure about your photo editing skills, you can also hire someone who would do the job for you. There are tons of offers of such services on the internet. We hired a few professionals:
Here are the professional retoucher’s results:
It took about six hours for a professional retoucher to complete the upscaling. She used various Photoshop plugins, masks, and filters. She also redrew specific details missing in the high-quality version of an image. The price for such work varies from $20 to $150 per hour and higher. The amount of work depends on the image’s quality and complexity, and upscaling degree.
Then we gave the same photo to freelancers at Fiverr. The guys all followed the same workflow: the Photoshop Preserve Details filter plus the Skin Finder Plugin. Each work has cost us $8.25, including Fiverr’s fee. Here’s the first result that we got from a Fiverr freelancer:
In general, we liked it, if not for some mural effects (flares) here and there:
Though Fiverr freelancers use the same instruments, the final image quality can vary greatly.
Such services do the same things as Photoshop but automatically. All you need is to upload your image, specify the target resolution, and click OK.
Let’s use PhotoEnlarger, one of the most popular services of this type.
Here’s how to increase image resolution using PhotoEnlarger:
In the output, you will get four photos enlarged with different algorithms. You can compare them and select the one that you like best.
Another similar service is ResizeFile.com that works like any other similar online tool: upload, wait a bit, download, that’s it.
It’s a simple online utility for enlarging pictures. The maximum size of the output picture is 3,000 px in width or height.
We got about the same result in both cases.
The image from PhotoEnarger is more grainy, but the difference is negligible.
Pros and Cons to using online services for upscaling pictures:
Artificial intelligence (AI) image enlargement works differently. First, AI analyzes large libraries of images in all resolutions and accumulates knowledge of textures, objects, and environments. Then it’s continuously training to recognize patterns and fix previous upscaling errors and artifacts. And the key point here is how well-trained an AI is. With enough training, AI-based upsampling exceeds the quality of any interpolation method.
An example of such an AI-based upscaling service is Icons8 Smart Upscaler.
Here’s how to use Icons8 Smart Upscaler to turn your images and photos into hi-res versions:
The output is similar to the pro retoucher work: AI has removed noise and other artifacts, added missing textures, and improved saturation.
Another similar service, Deep Image, is based on convolutional neural networks (CNN).
The picture is nice, but you can see some noise and bugs in textures when zoomed in.
Let’s compare both results with retoucher work.
The AI worked great, and the pictures are close to the professional retoucher result. The image processed by Smart Upscaler looks more natural and sharper when zoomed in.
We’ve covered methods and tools that you can use to enhance your image quality. You can now compare the best results of each approach:
Here are the conclusions we came to:
And here is a visual comparison to show the key differences between the four approaches to image upscaling:
|Free option||Quick ||Easy-to-use||Batch upscaling||No linits to image size|
|Free option||Quick ||Easy-to-use||Batch upscaling||No linits to image size|
|Based on interpolation algorithms|
|Baseb on AI|
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