So I want to use one of the many
online printer photolabs to send my photos to and have them print them and send them back. What is the best way to make sure the colors I see on my monitor match what I get back from them? What am I up against? What is perhaps the biggest factor? White balance?
So I want to use one of the many
The biggest is color management by far. I use the term "photolab" instead of "online printing company."
Ensure your files have the correct color space attached. Many pro labs support a variety of color spaces, so you should use the one that they recommend.
Have your monitor color calibrated using a hardware colorimeter. Eye balling it, will not give you the best results. When color calibrating it, you need to make sure that the ambient light levels are consistent with how you typically view and edit your photos.
Once your monitor is calibrated, you need to obtain the ICC color profiles for the printers from the photolab to which you will send your photos too. With the correct ICC profile, you can "proof" your photos using software which will show you how you can expect your photos to look.
Above all else, contact the photo lab and find out what steps they recommend for getting the most accurate colors from their prints.
If by chance, the photolab does not supply ICC profiles, and you have your heart set on still using this lab, you can send them a color calibration target to print. You can then send this image to a specialist company who will build you an ICC profile, and then proof the images. This of course is a royal pain, so you might as well just find a different lab to do business with.
You're up against a few factors:
Your own monitor color situation. Unless you're using a color calibration tool, it's very likely that your monitor isn't showing color correctly and you're either used to it or it's close enough that you haven't noticed.
Not all software treats color space the same or even at all. Depending on what you're using to view the image, it may appear subtly different.
Color space of the image. I'm pretty certain that all cameras support sRGB, but some also do Adobe RGB (and possibly even ProPhoto RGB). sRGB is standard for monitors and many (or most) consumer grade printers, but if your image is in Adobe RGB, well it may come it differently when professionally printed. However, I suspect that you're shooting sRGB. To find out, in Windows, right click on the image, select properties, click the details tab, and scroll down until you see the line 'Color representation' and it will tell you.
White balance is a factor, but only if they actually correct/change it. Possible, I suppose, but I'd be surprised.
RGB vs CMYK. Monitors are RGB, which is additive (colors add to create white) and printers are often CYMK which is subtractive (colors add to remove white). The theory of color is a little large to go into here, but suffice to say they are different and perfect match would be quite difficult.
Anyways, if I were to hazard a reason why a print would come back that doesn't match your monitor, it would probably be for the first one I mentioned, the remainder are highly unlikely to be problems for most digital images.
See if your printer uses ICC profiles, if they have calibrated their printers correctly and you use color management you should be able to embed a custom profile and they will match what you see.
As an example, WHCC has their color management guidelines in their faq.
These are their current guidelines:
Q. How do I calibrate to your printers? A. You don't calibrate directly to our printers. You calibrate your monitor and generate a monitor profile which software like Photoshop uses to show you accurate color on your screen. We calibrate and balance our printers to create a printer profile. Using a standard working color space like Adobe RGB 1998 or sRGB and embedding this in your file allows the printer software at WHCC to use our printer profile to make sure what is printed is what you saw on your screen. We recommend all clients perform hardware monitor calibration. This is a relatively straightforward and simple procedure. We recommend the X-Rite i1 Display.
Q. Do you supply any profiles? A. Yes. Once you have an account number, you can download ICC profiles for soft proofing purposes. The profiles are for all of our printers and we also have instructions on how to properly use them. Under no circumstances should you convert to our printing profile or embed it in your files.
Q. Is it okay to embed an ICC profile? A. Embedding a valid ICC profile in your image is very important. Without embedding the profile our software has no idea what colorspace your file is in. This will result in uexpected color in the prints. All files not tagged with an embedded profile are assumed to be in sRGB.
Q. What colorspace do you accept? A. We accept any colorspace as long as it is embedded in the file. Our software will read the colorspace embedded in the file and print appropriately for that colorspace. We recommend the use of a standard working space profile such as Adobe RGB 1998 or sRGB.
Obviously this is one one printer, and they will each have their own specific methods of handling this issue, but most of the information is going to be similar to this.