What is the blurring of pixels for fidelity called?

Question

In most computer graphic design, when detailed images are drawn at the pixel-level the pixels are blurred with those next to them to make the border look more natural and less pixelated. I know in some things such as text rendering this is called 'anti-aliasing', you can see an example of what I'm talking about in one of the first diagrams on the Wikipedia article.

The term 'anti-aliasing' and 'aliasing' seems to refer to more than just blurring pixels to produce a more realistic image though.

In the game Lethal League, this technique is not used so as to give the graphics an interesting aesthetic, where the art seems particularly pixelated even though the pixels are no bigger than normal (you can see what I mean here on the Lethal League website)

So, is there a name for this technique used to make lines look more like lines and borders look less pixelated etc.? I don't think 'anti-aliasing' is the term I'm looking for as sometimes it's not used to avoid an 'alias', as seen in the Lethal League art where it is specifically avoided to produce a specific aesthetic.

You would use the word like "Most images are/use [word] to make them look less pixelated" or "Some graphic designers avoid using [word] to create a pixel-art aesthetic" or something like that.

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EDIT:

Just to clarify why I didn't want to use the term anti-aliasing: this term is used for the removal of aliasing, where the jagged edges are an unintentional and unfaithful representation of what you are trying to make an image of. This is why I gave the Lethal League example, there's no aliasing there as it's an intentional aesthetic. So the real question I was trying to ask is that if someone were to blur the lines on a piece of pixel art to make it more realistic, what would that be called? It's not anti-aliasing as the pixelisation was intentional, aliasing is caused by the computer attempting to pixelise something that's not pixelised. I'm simply looking for the word to describe blurring the lines rather than removing computer-generated unwanted aliasing.

Answer 1

The "blurring" or shading of pixels along a hard-edged graphic is called anti-aliasing.

Answer 2

Adding blur that didn't exist due to a physical process, in order to more closely mirror the smoothly rasterized look of a photograph/scan/capture would be a form of skeuomorphism. This isn't a specific process, though. I suspect there isn't a word for this particular practice, because this sort of "blurring," arises from antialiasing at the time of image creation — Photoshop for example antialiases the shape of its brushes, so that when you draw a line in their software, it is antialiased by default. You can turn this off, but attempting to blur it after the fact will get you much less convincing/pleasing results.

The closest I can think of is this - https://i.stack.imgur.com/GmB0G.jpg - which is usually used to "upsample" an image, or make it larger.

Conveivably, this could be the process you're referring to. One could take a pixelated image, double its size via the algorithm in the link above, then scale it back down to the original size. This should result in some form of less-than-ideal antialiasing, that could have the effect you're looking for.

Answer 3

When you sample the 2D or 3D data behind each pixel exactly one time, you get the aliased look from your game example.

When you sample each pixel several times, i.e. its subpixels (a.k.a. oversampling), you get an anti-aliased look.

It looks softer but it's not related to blurring which also takes samples outside the pixel's area into consideration, creating an out-of-focus effect.

A computationally very cheap blurring technique is to use the pixel's neighbor pixels as samples (using for example a 2x2 or a 3x3 median filter).

This appears to be what you're after. I would call it pixel-averaging or just blurring, as mentioned.

Answer 4

In graphic design, we call those kinds of graphics "hard-edged," just as @DKT offered up.

Answer 5

If you want to keep the number of pixels the same, you might be talking about low-pass filtering:

A low pass filter is the basis for most smoothing methods. An image is smoothed by decreasing the disparity between pixel values by averaging nearby pixels – northstar-www.dartmouth.edu

If you want the result to have more pixels than already exist, you might be talking about interpolation:

Interpolation (sometimes called resampling) is an imaging method to increase (or decrease) the number of pixels in a digital image – www.dpreview.com

• Better pictures of interpolation and more technical details are at www.cambridgeincolour.com

• Low-pass filtering is essentially interpolation, over larger areas of pixels than necessary, without changing the number of pixels

Answer 6

The terms I have heard for this is "smoothing" or "softening".

See the Wikipedia article on Image editing.