Thanks for your comments.
The processing was very light. I made only histogram strech and curves on the L. The RGB processing was a bit tricky because ... there's no background in the picture, lot of stars everywhere and all reicipes i usually use didn't work so i made the white balance by hand and i got one not bad by luck only. Then i made a small convolution of the RGB before the combination with the L. I did not use HDRMT, but i usually use it on the nebulaes (like my M42, Eta Carina, Tarentula you can see on my website). I don't think big globular cluster need heavy processing : most important is the seeing, the autoguiding and the optical quality of the scope to resolve the stars.