The article mentions two: unpacking 24 bit values and matrix multiplication, both might be something you'd find in a software video (de)compressor or a computer game

Where did you get 24 from? It's about vectorizing loads of 3 elements. The elements don't have to be 8-bit. The second example uses floats.

Yeah, but 24-bit values (RBG) are what you'd find in video and gaming applications.

Games, at least what I've seen, usually just don't use 3x(8|16|32) bits per pixel, if it's not needed as alpha. It's pretty rare to pack 24/48/96-bit pixels in memory. Traditionally, unaligned loads are just not worth it.

Sometimes packed formats were worth it. I remember doing RLE schemes for fast "alpha blending" (anti-aliased blitting really!) back in 2000 or so, before MMX or GPUs were common. The scheme I used had three different types of run lengths. Completely transparent, pre-multiplied alpha blended and completely opaque. 16-bit pre-multiplied values were in memory in 32-bit format like this: URGBU00A. Groups of 5 bits, except U denotes unused single bit. Frame buffer in RAM was in 15 bit format, 0RRRRRGGGGGBBBBB. With this scheme, alpha-blending needed totally just one multiply per pixel [1], compared to three with usual pre-multiplied alpha or six with normal alpha without pre-multiplication.

[1]: Frame buffer pixels were masked and shifted into 000000GGGGG000000RRRRR00000BBBBB, multiplied by A and shifted back in place. Because all values were 5 bit entities, no overflow (overlap) could occur in multiply, thus one multiply yielded 3 multiplied frame buffer pixel values, for R, G and B!

Presumably loading a 3D vector would be a good use-case?

From the story....

  1. Image conversion (RGB structure to some other)

  2. N-dimentional coordinates. (Normalize array of XYZ points)

  3. Multiplication of vectors by constant matrix

Faster multi dimensional loops. Quicker raw image compression.

That are few things that came across my mind.