post processing for screen.

[unfocused]

Maybe I'm missing what the OP is referring to...but...

When you say "output for print" do you mean photographic prints or do you mean photo books?

If your final destination (so to speak) is a printed book, even one of the short-run custom press books, you need to convert your files to CMYK and adjust accordingly. After having a very bad experience with one publisher, I posted a similar question a few months back. I got some very good advice from some color professionals. I was also directed to the "Blurb" help site on color management, which was really excellent. I followed their advice, had a small test book printed to see the results, was pleased and then went ahead with my proof copies.

Some printers don't require you to convert to CMYK, but be forewarned that they are going to be printed in CMYK anyway, so you are really just taking a shot in the dark if you don't do the conversion yourself.

But, while you need CMYK for printing, you would never want to use it for web displays.

As far as monitors and web colors go, as others have said, unless you want to go around the world and personally adjust the monitor of everyone who looks at your images, there isn't a whole lot you can do. I have the nasty habit every time I go into an electronics store of going to their computer displays and punching in my website address to see how my site displays on their browsers and monitors.

Usually I find that the images display okay, although there can be quite a bit of color variation. I just look for images that are really out of whack and then do some soul searching about whether or not I need to delete the image from my site. Usually, a bigger and more annoying issue is when the browser doesn't display the site properly.

I'll tell you that most images look really, really good on iPads. But, because Apple doesn't play nice with Flash, they will only display in HTML. So, you need to make sure you have a program that defaults to HTML when Flash isn't available (SimpleViewer is one).

If I were in this for paying jobs, I would invest in a nice tablet and build my promotional materials around that tablet, so I could take it with me to show clients the images, rather than risk having them look at them on their monitors with their 1995 version of Internet Explorer.

As I said, I have no idea if this is where you were going, but it's my 2-cents worth.

[archangelrichard]

CMYK (Carmine, Magenta, Yellow, Black inks; for print these are standard while screens use Red, Green, Blue Phosphors (and there is a difference between sRGB and standard RGB) - you need a program that does both well

YES, Grigbar, the number of bits does make a difference; it's just that ho one else is using them so it's a moot point (kind of like the Betamax / VHS or Blu-Ray / Regular DVD argument - everyone has regular DVD so that is your standard

When you say "screen" it depends on what you are talking about; all screens will differ in how they display any color so you can't be color-critical like you can in print; we all set the brightness where WE want it; even screen widths are different so don't be so picky about it and adjust for what YOU want, that is the best that you can do

[xROELOFx]

i'm actually not really worried how my pictures look like at someone else's monitor. if i post proces them and they look good on my (calibrated) monitor, they should also look fine on other monitors. if they don't look good, other things won't look good either. so if a monitor is badly calibrated, or has weird saturation or brightness, it would not only affect the photos but everything the monitor displays.

[Janco]

CMYK (Carmine, Magenta, Yellow, Black inks; for print these are standard while screens use Red, Green, Blue Phosphors (and there is a difference between sRGB and standard RGB) - you need a program that does both well

I thought C in CMYK stands for Cyan, which is something blue'ish, while Carmine would be a pigment of a red'ish colour...? 

[xROELOFx]

CMYK (Carmine, Magenta, Yellow, Black inks; for print these are standard while screens use Red, Green, Blue Phosphors (and there is a difference between sRGB and standard RGB) - you need a program that does both well

I thought C in CMYK stands for Cyan, which is something blue'ish, while Carmine would be a pigment of a red'ish colour...? 

yes, you are correct. it's cyan, magenta, yellow and black.