Lossless Compression algorithm

[Pryme8]

I can not for the life of me remember what the algorithm is called and https://en.wikipedia.org/wiki/Lossless_compression has so many types not sure which is the one I was looking for.
What's the "best" method for compressing an array of any length with values between 0,255? 
I used one in the past and it had a look up table I think and was like an array with a bunch of other arrays inside of it.  It was a long time ago so sorry if this is not very descriptive.

End goal is after serialization of a ImageData.data into a smaller/stripped down array is to then hit it with a lossless compression algo before it exports so I can get the Image data I am saving even smaller.

[brianzinn]

Was it LZW? https://en.wikipedia.org/wiki/Lempel–Ziv–Welch

[Pryme8]

YAAAASSSSS, thank you!  I had old references that I would work from but they were on one of my other hard-drives so I dont have access to them and have to do it from scratch, but I remember it being super easy to implement.

[Pryme8]

Now before I start getting super into deploying a LZW algo, I wanted to see if anyone knows of any lossless methods that will encode a file like this:

https://github.com/Pryme8/TileMaster/blob/gh-pages/editor/imgs/Stone_Platform_32.tms

to the smallest possible file.

[BitOfGold]

@Pryme8 Two easy methods for compressing files:

- you can use deflate on webserver: all files arrive with automatic gzip transfer encoding to the browser. just some  .htaccess settings on apache.
- jszip. Easy file access from a zip file. I'm already using this (in my engine I'm working on), not just compression but lower the number of http requests. https://stuk.github.io/jszip/