Question

I am trying to develop a paint brush application thru processingjs.
This API has function loadPixels() that will load the RGB values in to the array.
Now i want to store the array in the server db.

The problem is the size of the array, when i convert to a string the size is 5 MB.

Is the best solution is to do compression at javascript level? How to do it?

Answer 1

See http://rosettacode.org/wiki/LZW_compression#JavaScript for an LZW compression example. It works best on longer strings with repeated patterns.

From the Wikipedia article on LZW:

A dictionary is initialized to contain
the single-character strings
corresponding to all the possible
input characters (and nothing else
except the clear and stop codes if
they’re being used). The algorithm
works by scanning through the input
string for successively longer
substrings until it finds one that is
not in the dictionary. When such a
string is found, the index for the
string less the last character (i.e.,
the longest substring that is in the
dictionary) is retrieved from the
dictionary and sent to output, and the
new string (including the last
character) is added to the dictionary
with the next available code. The last
input character is then used as the
next starting point to scan for
substrings.

In this way, successively longer
strings are registered in the
dictionary and made available for
subsequent encoding as single output
values. The algorithm works best on
data with repeated patterns, so the
initial parts of a message will see
little compression. As the message
grows, however, the compression ratio
tends asymptotically to the
maximum.