I notice that even though I have the output profile for the printer and convert my RGB files to that printer, the colors in the final printed form may come out weak, washout etc. What is the best way for me to get the colors richer, vibrant after I have done the conversion?

Any help would be greatly appreciated.

Not really. Assuming its a good profile, you're seeing the soft proof and results of what a nice RGB, wider gamut document will look like. I'd be more concerned about color shifting (which a good profile should not produce).

I don't know what you mean by "converting the RGB files to that printer". You select a working colour space for adjusting your photos - if your images are 16 bit, ProPhoto is a good colour working space to use; if your files are 8 bit, Adobe RGB(98) would be more suitable. Set-up your SOFTPROOF in Photoshop to contain the printer profile and the Rendering Intent you will use for printing. For example, if you are using say Epson Enhanced Matte paper, and Relative Colorimetric Rendering Intent, create a SoftProof condition with these selections (View>Softproof>Custom). You can toggle the softproof display on and off with CTRL Y.

Assuming your monitor is properly calibrated and profiled, and above all not too bright, make sure SoftProof is activated with the Printer Profile you will use for printing. Look at the image. If you don't like what you see, use Curves and/or HSB Adjustment Layers to fix luminosity and colour to your taste. Save the image.

When you print, in the Print dialogue, make sure you Let Photoshop Manage Color, make sure you have the same printer profile and Rendering Intent selected in the Print dialogue window, make sure Printer Color Management is OFF in the printer driver, make sure the correct paper is selected in the printer driver, then print. What comes out of the printer should be a reasonably close approximation of what you see on the display.

Thanks Andrew.

Mark - You may have missed the title/description.

As a follow up - how does one get colors in a 4-color sheet fed output to be more saturated and vibrant?

Oh - you are talking about a press, not an inkjet process? Then, different story.

I'm just a photographer, not a pre-press person, but I do a lot of this work as part of my staff job. Even with a calibrated monitor and correct profiles, images do lose a lot on press. So I usually punch up the RGB file before the conversion -- add some saturation, and use a wide-radius Unsharp Mask to enhance local contrast. Then convert to the proper CMYK profile, do the final pre-press USM, and save it out as a TIFF.

Note that the RGB file looks "overdone" before the conversion. I realize that this seat of the pants method might not be "correct," but we get good results on press. It will probably take some experimentation using press proofs (printed) and several finished projects on the press.

Edit: I'll add that I start with a good 16-bit RGB file in ProPhoto or Adobe RGB.

I found this tutorial by Schewe to be helpful when I first started doing conversions. When I can get a good profile, I do the conversions of my work for magazine articles. Luckily many of my main magazine clients use the same printer who has great profiles so I get plenty of practice and feedback every month.

Schewe CMYK

Thanks Kirk.