Application.ExternalCall random escaping of long string (base64)

Unity Engine
1

I am trying to send an image in base64 format from Unity to javascript (and on to flash).
But the long string gets altered in seemingly random ways. I can’t work it out but certain sequences of characters seem to end the string prematurely and some characters are altered.
There was a similar question on answers http://answers.unity3d.com/questions/10842/what-is-the-maximum-byte-length-of-applicationexte.html

any update Unity?
whats the deal on this?

2

there is a limit on how much data you can send. Unsure where it is at the time, but sending around images is pretty surely hitting the wall I think.

3

that would be unfortunate - i only wanted to send a 55x55 PNG.