Lempel Ziv compression implementation

[mathieu]

Hi there,

I am starring at page 43 and up (5.4 Example For Lempel-Ziv encoding) from the following document:

ftp://medical.nema.org/medical/dicom/1989/PS2_1989.pdf

Does anyone recognize the associated algorithm ? Is it available in a publicly available library ?

Thanks much for comments

[Robert Wessel]

On Sat, 25 Jul 2015 06:30:55 -0700 (PDT), mathieu

Post by mathieu
Hi there,
ftp://medical.nema.org/medical/dicom/1989/PS2_1989.pdf
Does anyone recognize the associated algorithm ? Is it available in a publicly available library ?
Thanks much for comments

Page 11 seems to be clear that it's just LZW as described in the
original Welch paper, per reference #21.

[mathieu]

Post by Robert Wessel
On Sat, 25 Jul 2015 06:30:55 -0700 (PDT), mathieu

Post by mathieu
Hi there,
ftp://medical.nema.org/medical/dicom/1989/PS2_1989.pdf
Does anyone recognize the associated algorithm ? Is it available in a publicly available library ?
Thanks much for comments

Page 11 seems to be clear that it's just LZW as described in the
original Welch paper, per reference #21.

Any implementation out there that support 16bits input. Most implementations I found assume 8bits input.

[glen herrmannsfeldt]

(snip)

Post by mathieu

Post by Robert Wessel
Page 11 seems to be clear that it's just LZW as described in the
original Welch paper, per reference #21.

Any implementation out there that support 16bits input.
Most implementations I found assume 8bits input.

LZW finds repetitions in the data. Repetitions in 16 bit data are
also repeitions in 8 bit data, so it will still find them.

LZW initializes the dictionary with all 8 bit values, which isn't
so bad. If you made one that initialized with all 16 bit values,
it would have to start with 17 bit codes, which could be a lot
less efficient.

LZW also works well for smaller data, for example files full of
binary (ASCII '0' and '1') data, even if the actual 0's and 1's
are random, will compress well. It will find strings of 1's and
0's and code for them.

-- glen

[Dave Brown]

Post by mathieu

Post by Robert Wessel
On Sat, 25 Jul 2015 06:30:55 -0700 (PDT), mathieu

Post by mathieu
Hi there,
ftp://medical.nema.org/medical/dicom/1989/PS2_1989.pdf
Does anyone recognize the associated algorithm ? Is it available in a publicly available library ?
Thanks much for comments

Page 11 seems to be clear that it's just LZW as described in the
original Welch paper, per reference #21.

Any implementation out there that support 16bits input. Most implementations I found assume 8bits input.

https://github.com/JavaScript-Packer/lzw-javascript-packer.js