[noggin]

The problem with MKV instead of ISO is that the image are in half size (two image on 1920x1080) and the final quality is lowest than blueray... no ?

No. If it's ripped correctly, the video quality will be absolutely identical. The only difference is that an MKV can only hold a single video (e.g. one movie) while an ISO can hold an entire disc (e.g. movie plus extras). So if you want to store more than just the film, you would need to rip it to several separate MKV files. On the plus side, when converting to MKV you can delete things like disc menus, and audio and subtitle tracks that you don't need - that saves a bit of space.

If you want to try converting to MKV, you could perhaps try downloading utility called MakeMKV - it's designed for ripping straight from disc to MKV files, but it works very nicely with ISOs too.

Thanks Shasarak for you answer and explanation. 

I'll tests makemkv.. 

But i still don't understands why video quality should be the same. In one case we have 960*1080 images (per eyes) in other we have the double size 1920*1080 (per eyes). This should be a major difference in screen. Same if pictures are resized by TV in HD, the source is important ...  no ?

TL;DR If the MKV contains MVC 3D video - it's identical to the video in an ISO - so identical 1920x1080 resolution for each eye feed.  It's only if the MKV contains HSBS or HTAB, and not MVC, that you get 960x1080 or 1920x540 reduced resolution.

Please remember that MKV is just the container for the video - it doesn't define how the video is encoded - that's down to the codecs and resolutions used.

It's possible to store MVC video in both an ISO and an MKV wrapper.  The quality will be the same in both cases as the MKV version will be carrying identical bitstreams to the ISO if it is ripped correctly.  

The MVC video codec is based on a single 1920x1080 h.264/AVC stream for one eye (which is also the stream played in 2D compatibility mode), and a secondary MVC 'difference' stream that allows a second 1920x1080 eye feed to be constructed from the primary h.264 stream (there is a huge amount of redundancy between eye feeds, so this method is a very efficient encoding system).  This is the format used for commercial 3D Blu-ray releases, and is a format that can now be carried in an MKV wrapper.  

HSBS and HTAB are not formats used on ISOs.  For a long time 3D ISO files were converted to MKV as HSBS (2 x 960x1080 feeds next to each other in a 1920x1080 frame) to allow  these files to be replayed on devices that weren't able to play MVC content (MVC replay is still rare), and which weren't able to output frame packed HDMI video (again 3D frame-packed output over HDMI is still rare). HSBS and HTAB are identical to 2D video files - and can thus be played back on any media player capable of playing 2D content.  However, unlike MVC video replayed on a frame-packed output player, you only got reduced resolution as a result.