RGB to YUV Performance Improvements

[Charlie-Zheng]

Changed to use integer math instead of f32 method. Adjusted to use iterators instead of array indexing.

New benchmarking timings on my PC (Windows 10, AMD Ryzen 7900X)

test convert_rgb8_to_yuv_1920x1080 ... bench:     305,200.00 ns/iter (+/- 26,439.00)
test convert_rgb8_to_yuv_512x512   ... bench:      44,606.80 ns/iter (+/- 1,529.76)

Old benchmarking timings

test convert_rgb8_to_yuv_1920x1080 ... bench:   4,473,440.00 ns/iter (+/- 368,726.00)
test convert_rgb8_to_yuv_512x512   ... bench:     543,745.00 ns/iter (+/- 9,916.00)

[Charlie-Zheng]

The build errors appear to be related to the dependencies of the crate and not due to the changed in this PR.

  Downloaded moxcms v0.7.5
error: failed to parse manifest at `/home/runner/.cargo/registry/src/index.crates.io-6f17d22bba15001f/moxcms-0.7.5/Cargo.toml`

Caused by:
  feature `edition2024` is required

  The package requires the Cargo feature called `edition2024`, but that feature is not stabilized in this version of Cargo (1.84.1 (66221abde 2024-11-19)).
  Consider trying a newer version of Cargo (this may require the nightly release).
  See https://doc.rust-lang.org/nightly/cargo/reference/unstable.html#edition-2024 for more information about the status of this feature.
Error: Process completed with exit code 101.

[ralfbiedert]

Can you rebase and try again?

[ralfbiedert]

BTW, I can confirm a ~14x performance increase here locally, absolutely outstanding!

[ralfbiedert]

Thanks! I'll credit you in the README, let me know if I shouldn't.