RGB to CMYK without losing quality

Snehal,

A lot depends on the particular colors you're using in RGB, what sort of CMYK printer or press you're using and just how you're actually converting to CMYK. Most images print just fine in CMYK, as can be seen by the many thousands that print every day in magazines and newspapers around the world. CMYK's weakest areas are bright saturated blues, which will always print like crap because the inks just cannot print those colors. You haven't told anyone exactly why your conversions look like crap, only that they do. If you posted an example, more specific help could be given, but the bottom line is that there are always going to be some compromises going to press and you, as the designer, have to take those possibilities into account when doing your design. You can also trick the viewer's eyes into thinking the image is more saturated than it really is by intelligent use of color contrasts in images and designs. For instance, using a bright yellow, something that presses print quite well, next to the best blue you can print, will make that blue appear bluer and more saturated than it really is. Of course, if you need exact and specific color matches, you can always go to additional spot color plates using Pantone or other color inks, at an added cost in both money and complexity.

Entire books have been written on this subject, and for good reason.

CMYK cannot reproduce the colors in RGB. I'm pretty sure this is covered in the help, or any basic design class.

http://www.printernational.org/rgb-versus-cmyk.php

http://www.printingforless.com/rgb-cmyk.html

http://en.wikipedia.org/wiki/CMYK_color_model

http://en.wikipedia.org/wiki/Color_management