arsh,
there's 2 steps really, the source and the compression once oyu have the source. Screw up at either stage can result in a poor product.
Directors etc generally supervise the first step, only some (even in hollywood) supervise the second. So you can have a perfect source but have it ruined by compression goof ups. On the other hand, you can have the best compressionists work on something but if the source is poor, it still looks like crap.
For example, most of Warner Bros new releases (both r1 and r2) are being done by a new team of compressionist. You only have to take one of these new releases to see that for some reason, whether thats inexeprience or promotion of HD-DVd, they're of lower quality than anything WB has put in the last year new release wise, or even compared to current new releases of older films (which are being handled by the 'old' compressionist). There's no dispute that the source here is still high quality, but the compression definitely isnt. Titles include things like The Departed, A Scanner Darkly, Blood Diamond. These have received rave reviews on most dvd review sites, and admittedly get a lot better around the 20 min mark for Blood Diamond and Departed, but anyone with any sense of picture quality can see that the initial sequences look terrible.
Of course, these poorer new WB releases are still miles ahead of what hindi dvds look like