How to enlarge images with no pixellization and minimal quality degradation (using free software)


Have you experienced a situation where an image you are interested in using is smaller than you would like it to be, whether it might be for printing purposes or for use in illustration projects or even for usage on the web, etc? Typically, straight-enlarging of an image comes with too much of a degradation in quality, with visible pixellization and undesirable artifacts, and a general loss of detail.

This post will describe a process that can lead a different outcome.

To be clear, the steps described here will not magically produce a perfect image out of a source which (by definition) is far from optimal.

Rather, what is on offer here is the prospect of processing the enlarged image algorithmically to get a much better/cleaner looking resized image than otherwise would be the case.

Clean enlarge illustration2

Nor is this post about manual image processing or Photoshopping techniques. The tool used here is a free software called SmillaEnlarger, and it can perform image enlargement quickly and easily (and automatically) in one or two clicks.

To demonstrate the kind of results that can be obtained, I will attempt to enlarge a test image using the different profiles that are pre-built into the application.

First, step by step instructions, then an overview of a test resize.

Step by Step:

Step 1: go to the SmillaEnlarger web site and download the latest version. Unzip then run SmillaEnlarger.exe (no installation needed).

Step 2: Once the program runs, simply drag and drop the image you want onto the interface.

Smilla 0 Cr

Step 3: Enter the desired output height in the top left. Note: the output width will be calculated automatically and will assume the same aspect ratio as the original.

Smilla1 Cr

Step 4: use the dropdown under the “Enlarger Parameter” section to select one of the available presets.

(Optionlly) press the “preview” button on the right to get a preview of what the enlarged image will look like under each setting. You (move the image slightly with the mouse to get back to the default, no-processing enlargement).

Smilla2 Cr

Step 5: enter a desired filename for resized image (or use the default provided) then click “Enlarge and Save”.

Smilla3 Cr

Step 6: (optionally) go back and redo steps 4 and 5 for each settings profile in the dropdown. Later, you can compare the different outputs to see which one you like best.

That’s it, you’re done!

Overview of test results:

Original image: 250×147, see below (actual size). The desired output size was 470×267.

RH Orig 250x147

I choose this output size (roughly double the original) because I wanted to publish the resized images on this blog in their actual size, and I am restricted by the width of this column.

But I’ve performed enlargements that are x5 or x6 the size of the original, with the same general results as the ones presented below.

1. Control: The enlarged image below was not done in SmillaEnlarger, rather it is a normal resize performed in Photoscape (Lanzcos resizing filter). I include it here for reference.

RH Orig 470 -lanzcos

Notice the pixellizations around the text and mountain areas, and the chunkiness of the sky in the midde.

2. Default: this is the “default” settings profile in SmillaEnlarger.

RH default 470

Both the text and mountain objects are cleaner, and the chunky blocks in the open sky is replaced by a more textured/grainy look (which may be much more preferable in print or other contexts than the pixellized chunks).

3. Sharp: this is the “sharp” settings profile in SmillaEnlarger.

RH sharp 470

This profile produces a less grainy image, which might be better suited for some projects, but the artifacts around the objects (text/mountains) are a little more visible than the ’default’ profile.

4. Sharp & noisy: this is the “sharp & noisy” settings profile in SmillaEnlarger.

RH sharp&noisy 470

It removes the blocky chunkiness, opting for a more “cloudy” and less grainy texture. Although in my opinion much better than the control, it may not be the best treatment of this particular image, but I’ve seen this profile do an excellent job on a different kind of image that is busier and features more objects.

5. Painted: this is the “painted” settings profile in SmillaEnlarger.

RH painted 470

This profile does an excellent job with both texture and detail, but will give your image a certain “drawn” quality. It works really well for illustration type projects that don’t necessarily have to look like photographs, but is not very well suited for, say, pictures of people (see a tiny webcam picture that I snapped of myself and enlarged below, where the beard and ear and other elements look like an oil painting).

WebcamImage-267 painted

6. New: this is not a built in settings profile but is rather one that I made, intended to be a cross between the “default” and “painted” profiles, which are my two favorites.

RH new 470

I kind of like both the grainy texture and the sculpted edges around the visible elements simultaneosuly. I find that I use this profile quite a bit

If you want to create this profile click the “new” button under the preview section, then check “allow changes” and use the following settings. You can edit the name is well; it doesn’t have to be called “new” 😉

new profile

The point is that with a tool like this one, you can really get a much better result than a simple image resize. All of the versions above (2-6) are vastly superior to the simple resize in my opinion.

If you know of other tools or methods to do this sort of thing, please let us know in the comments.