Open source at all? Id be happy to add that functionality.
I have similar script, but it is more powerfull (check below for extra parameters), will put it on github when will have time or can sell it to you very cheap.
I made this:
Link is:
[img] http://amacar.hostei.com/generateImage/index.php/?VALUE=10&CUR=USD&TYPE=24h_avg&TIMESTAMP=YES&PRECISION=7&COLOR=00FFFF&SIZE=12&FONT=calibri [/img]
Parameter VALUE is just amount you want to convert to BTC
Parameter CUR is currency and could be any value from:
https://bitcoinaverage.com ('USD', 'EUR', 'GBP', 'CAD'...), default is USD.
Parameter TYPE could be 'ask', 'bid', '24h_avg', 'last', default is last.
If parameter TIMESTAMP is 'yes', then timestamp is added to image, otherwise no. Default is no timestamp added.
Parameter PRECISION allows you to round calculated value to decimals. Default is 5.
Parameter COLOR will change text color. Accept HEX values, default is black.
Parameter SIZE is size of text, default is 11.
FONT is font of text, default is arial.
Currently supported fonts (can add more):