So from what I've understood yesterday the available bandwidth depends on your SteemPower .. the more you have the heigher your bandwidth is.
You can manually check your bandwidth using tools like Steemd: https://steemd.com/@muksihs
Or by using the
public List<ExtendedAccount> getAccounts(List<AccountName> accountNames)
method of SteemJ.
I've been logging getExtendedAccount().getAverageBandwidth() and getExtendedAccount().getAverageMarketBandwidth(), and there seems to be a formula needed with some other value unknown to me to figure our their relationship to determining available bandwidth.
(muksihs bandwidth limit exceeded. Please wait to transact or power up STEEM. this error message indicating that you should power up when you can't without bandwidth is annoying and frustrating)
This tutorial provided by @jfollas looks pretty good: https://steemit.com/steemdev/@jfollas/write-a-steemit-web-app-part-7-bandwidth-availability
You may could create a GitHub issue for SteemJ and request this functionallity? Or even better - If you have the time provide it as a pull request if you implement it for your image library? =)