Anti Aliasing

Aliasing:

• Aliasing is the generation of false frequency along with the correct one when doing frequency sampling.
• For images, it produces a jagged edge.
• For sounds, it produces a buzz.

Effects of Aliasing:

• Jagged Profiles
• Loss of Details
• Disintegrating Textures

Anti-Aliasing:

• It is smoothing of image or sound roughness caused by aliasing.
• In images, adjusting pixel intensity we can eliminate the aliasing.
• In sounds, aliases are removed by eliminating the frequencies above half the sampling frequencies.

Methods of Anti-Aliasing:

• Increase the sampling rate. For that we use MSAA, SSAA and Custom modes like EQAA and CSAA.
• Blur the edges or contrasts. For that we use MLAA, FXAA and SMAA. It is also called Post Anti-Aliasing.

1. SSAA (Super Sampling AA) and FSAA (Full Scene AA):

• First type of AA introduced.
• Mostly used on photo-realistic images.
• Not used in games anymore.
• Resource usage is very high.

2. MSAA (Multisample Anti-Aliasing) :

• It is similar to SSAA but it refers to specific optimization of SSAA.
• That evaluates the fragment program once per pixel. Which means that MSAA snipes those pixels.
• There are 2x, 4x, 8x or 16x MSAA.
• It slower the system.

3. CSAA (Coverage Sample AA):

• It is created by Nvidia.
• It produces anti-aliased images that rival quality of 8x or 16x MSAA.
• CSAA made up with the intention to increase the quality of MSAA.

4. EQAA (Enhanced Quality AA):

• It was introduced by AMD. It was created with the same intention of CSAA to increase the quality of MSAA.
• It consumed the same amount of video memory as like MSAA.

5. MLAA (Morphological AA) and FXAA (Fast Aproximate AA):

• These are Post Anti-Aliasing modes, it use blur filters.
• FXAA consumes less power than other Anti-Aliasing methodes.
• One of the advantages was that it smooths edges in all pixels on the screen, includes pixels presents inside alpha blended textures and resulting from pixel shader effects.
• Then it increase the quality of MSAA.

6. SMAA (Subpixel Morphological AA):

• It is based on the Post-AA blur filter of MLAA. 
• The SMAA is very cheap compare to MSAA.
• It smoothes alpha tecture and greatly reduces the visible jaggies, but it doesn't blur the image as good.

7. TXAA (Temporal AA) :

• It is a very complex form of AA.
• it is not a Post-AA although it still blurs because of down sampling method used. 
• It takes lower consumption of power and best visual performance.
• It used at high resolutions(4k or higher).

Advantages:

• By using this we can smooth images.
• In sounds roughness caused by aliasing it can be smooth by using Anti-Aliasing.

Disadvantages:

• MSAA is  less performance intensive than SSAA.
• EQAA consumed more amount of video memory like MSAA.

My notes images: