LZW + Predict. is lossy?

[gregory]

What is lzw+predict.? Particularly the "predict" part. I'm assuming it's not lossless.

Thanks

[xnview]

What is lzw+predict.? Particularly the "predict" part. I'm assuming it's not lossless.

It's always lossless, LZW compression + predictor method (difference between pixel)

[gregory]

I assumed it was not because;

5.04MB Bitmap -> LZW = 4.52MB Tiff

and

5.04MB Bitmap -> LZW + Predictor = 1.99MB Tiff

It was such a big difference.
Thanks for clarifying.