How to do lossless compression with wavelets along with ROI

Hi all,

I'm currently starting a project with above titled problem. This is not about direcly a code. Question I'm having are...

• Does separating an image in to LL,LH,HL,HH parts actually do a lossless compression? (because neglecting LH,HL,HH will compress it lossyly).
• If I want to compress only some parts lossless (ROI), can It be done only rounding Non ROI parts of the LH,HL,HH ? Is this the standerd way?
• Are there any sugestions better than this?

Can anybody give me some hints about these questions.