I think it is caused by light pollution gradient. It is very difficult to get all the faint nebular detail to show without exagerrating any gradients present.
This is one of many objects I hope to image from a dark sky site once I get everything finally fine tuned. That day is very close. The extent of the LMC makes the use of any gradient removal tool also remove some real detail. I only put this up while I tried to remove this gradient.
Here is a better result of gradient removal from the same image using GradientXterminator without any further adjustment of levels and curves etc. Thanks for the critique it keeps me thinking more objectively about what is real and what is artefact.
1.1MB
http://members.optusnet.com.au/~cheekyfish/LMC_GX.jpg
Bert