Anti-Aliasing

What is Anti-Aliasing?

Anti-aliasing, sometimes referred to as AA, is the term signifying a software process to smoothen the edges of fonts or graphics objects to make them look round.

In other words, anti-aliasing refers to the process of removing the aliasing or the ambient occlusion effects from the 2D objects used in computer graphics. It helps in removing the jaggies.

Understanding Anti-Aliasing

What is Anti-Aliasing

Usually, images are produced by pixels, which are themselves rectangular in shape. This means that the edges of the round object look jagged.

The process of anti-aliasing typically helps in smoothing these edges to give them the perfect round look.

The jagged edges are the results of aliasing or undersampling. This means that the scan conversion is done by using sampling of low frequency, which results in the notable distortion in the images displayed.

This is where anti-aliasing comes into play. The process adds subtle color changes around the edges of the objects so that the human eyes are tricked when they view these lines. It is thought that the lines are smooth and not jagged.

The changes made in the color of the lines are minute and cannot be detected by the human eyes under normal conditions, or unless the image is magnified significantly.

Therefore, it is easy for these changes to blend easily with the background around the lines or curves. This makes the lines look true and smooth.

What are Anti-Aliasing Techniques in Computer Graphics?

There are typically four techniques of anti-aliasing namely, by post filtering or super sampling, displaying objects at a high resolution, pre-filtering or area sampling, and pixel phasing.

Using high-resolution display:

When objects are displayed at a high resolution, it will increase the sampling rate and reduce the aliasing effects.

This is because the jaggies become very small when an object is displayed at a high resolution, so much so that it cannot be distinguished by the human eye. Therefore, the edges get blurred and appear smooth.

Post Filtering or Super Sampling:

In this method, the sampling resolution is increased by treating the screen as if it is made up of finer grids that are a lot more in number.

This reduces the effective size of the pixels, even though the resolution of the screen is the same.

In this method, the average of the intensities of the subpixels is taken into account to find the average intensity of a pixel. Also, the intensity of each individual pixel is calculated.

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Therefore, sampling is typically done at a higher resolution and the image is displayed at a lower resolution or at the screen’s resolution, which is why it is called super sampling.

Usually, this method is carried out after the rasterized image is produced, which is why it is also called the post filtration procedure.

Pre-filtering or Area Sampling:

In this method, the pixel intensities are used, but these are calculated on the basis of the proportion of the areas overlapping each pixel with the objects that are to be displayed.

On the other hand, the color pixels are calculated in the reverse way, that is, on the basis of the overlap between the objects in the scene and the pixel area.

Pixel phasing:

This is a technique where the pixel positions are moved to almost the exact position near the object geometry.

In some cases and systems, the size of each individual pixel can be tuned for allotting intensities.

In addition to the above four techniques, there are also a couple of other methods followed in anti-aliasing, such as:

Compensating for line intensity differences:

This is the process followed when the diagonal line and the horizontal line are plotted on the raster display and the desired number of pixels to display both of these lines is the same.

This holds true even though the diagonal line is 1.414 times bigger than the horizontal line.

This reduces the intensity of the larger line, and to compensate for this reduction, the intensity of pixels is allotted based on the length of the line.

Anti-aliasing area boundaries:

This is the process that involves removing the jaggies from the edges specifically. The process is applied to scan line algorithms for smoothing the area boundaries out.

Also, in this process, the positions of the pixels are adjusted to bring them nearer to the area boundaries, provided repositioning of the pixels is allowed.

This is usually done on the basis of the percentage of the pixel area available within the boundary.

What is the Purpose of Anti-Aliasing?

The main purpose of the anti-aliasing technique is to smoothen the edges of the images on a PC by removing the jaggies. It blends the colors and makes them look less blurred and more natural.

Anti-aliasing today is even more necessary, especially on a larger screen, since both the resolution and GPU configurations have improved.

The anti-aliasing filter checks the under-sampled variables for specific frequencies.

It ensures that the sampling rate is the same as or greater than a signal component, based on the Nyquist theorem. This will eliminate the undesirable visual effects and jaggies.

Ideally, the anti-aliasing technique allows the images to achieve the four desired parameters, such as:

The anti-aliasing filters also play a significant role in producing specific functions such as noise filters and Analog-to-Digital Conversion (ADC).

What are the Different Types of Anti-Aliasing?

There are mainly two types of anti-aliasing methods namely, spatial and post-process anti-aliasing. Under these two broad categories, there are different types of subcategories, such as MSAA, SSAA, FXAA, MLAA, SMAA, TXAA, and DLSS. Each of these types has unique features.

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MSAA

Also referred to as Multi-Sample Anti-Aliasing, this type is characterized as follows:

SSAA

Also referred to as Super Sampling Anti-Aliasing, this type is characterized as follows:

FXAA

Also referred to as Fast Approximate Anti-Aliasing and designed by NVIDIA, this type is characterized as follows:

MLAA

Also referred to as Morphological Anti-Aliasing, this type can be characterized as follows:

SMAA

Also referred to as Subpixel Methodological Anti-Aliasing, this type is characterized as:

TXAA

Also referred to as Temporal Anti-Aliasing, this type created by NVIDIA can be characterized as follows:

DLSS

Also referred to as Deep Learning Super Sampling and developed by NVIDIA, this type is characterized as follows:

Does Anti-Aliasing Reduce FPS?

Yes, more often than not, anti-aliasing will lower the Frame Per Second or FPS. It will be more prevalent in the low-end systems because it will try to blend the colors in the boundaries to create a smooth illusion.

Typically, this effect will come at the cost of the computing power because further calculations will be added to each of the frames.

This will have significant effects on the workloads of two major components of the computer, increasing their jobs, namely:

This combined effect will reduce the FPS.

However, how much effect anti-aliasing would have on the FPS would typically depend on a few specific factors, such as:

The drop may be of only a few frames at times, but often it is by a large amount.

However, the more developed and modern Deep Learning Super Sampling (DLSS) technique tries to reduce the effects of anti-aliasing on the FPS and the performance.

Ideally, in this new image rendering technology created by NVIDIA, deep learning technique is used to generate an image that appears to be in a much higher resolution version of the original image which was in a lower resolution.

Also, the magnitude of the effect on the FPS will depend on the type of anti-aliasing technique used. For example:

The SMAA technique, on the other hand, will have an impact of magnitude somewhere in the middle of the two above techniques. It will blur the edges, but not the image.

And, if you consider TXAA, it will blur the image too much but will remove the shimmering effect.

This is because it is a Temporal Algorithm. In this case, the impact on the performance and FPS is comparatively high but is much lower in comparison to the effect caused by MSAA.

No matter which technique is followed, the gist of the matter is that anti-aliasing will enhance the graphics quality with less jagged and smoother edges, but at the cost of the FPS.

Anti-Aliasing Vs Aliasing

Questions & Answers:

Does Anti-Aliasing Reduce Lag?

No, anti-aliasing does not reduce delay or input lag at all. You will notice significant lagging in the input along with a notable drop in the FPS when you use this particular feature on your computer system, especially if it is loaded with a graphics card that is not very powerful.

Is Anti-Aliasing Good for Graphics?

Yes, anti-aliasing is very useful for graphics. In fact, it is one of the most important tweaks for graphics settings to make the images look better and optimize the images in a short amount of time. It will make your game look and feel great by smoothing the jagged edges of the images.

Is Anti-Aliasing Good for Eyes?

Yes, anti-aliasing a text or graphics will reduce the strain caused on your eyes dramatically, of course with a few specific exceptions. Remember, it renders characters that are pretty close to the intended design.

Conclusion

So, now you know that anti-aliasing is a technique that helps to abate visual defects in high-resolution images displayed on a low-resolution system.

You now also know its different types, purposes, importance, benefits, and utility, in spite of being a relatively old concept of smoothing images with round edges.