It is only when we print, that we can truly see what we have. Until we print, we are dealing with a half-realised, half-baked image.
Even though my computer monitor is calibrated and profiled to a tight tolerance, I still find discrepancies in my photographs once printed.
One of the most obvious errors is to discover that the brightest tones in the image, aren't really bright at all. The weird thing about this, is that once I notice that the tones aren't as bright in the actual print, I can now see the same problem when I view the image on the computer monitor. Even though when I looked at the image originally on the monitor, I thought it looked fine.
Our vision is often tricked and what we think we're seeing, isn't the case at all. Let's look at how our computer monitor may fool us. Take for instance this image below. It's a snow scene and I've chosen to work on it with a black background. The image looks pretty bright to me, almost white.
But if I change the background of my monitor to a light-grey tone, the snow scene doesn't look so bright any more.
And this problem just gets worse if I change the background to white as you can see below. The snow scene isn't looking so white any more, but instead, it looks quite muddy. Those bright tones are really mid tones.
Interestingly, if my monitor is calibrated correctly, the white background should simulate what the image will look like if printed on a white piece of paper, and in the example below, I may find that the image will be too dark once printed.
In the final image below, I've brightened it up a bit more to convey what I was looking for originally. This has only been possible because first I viewed the final edit on a white background on my monitor, but more importantly, once I printed it, I noticed it really wasn't as bright as I'd hoped. Now that I've corrected it and printed it, I'm happy, but surprisingly, it also stands up on my monitor also.
My monitor can only take me so far in evaluating my work. I really need to print it to get a better feel for how far I've taken the work, and how much further I still need to take it.
There is certainly some form of perception 'error' at play here and I'm sure it's to do with the fact that when looking at a file on a monitor, the light is transmitted, while looking at a print the light is reflected.
Either way, what I do find to be true, is that prints show up any discrepancies in my images more easily than any computer monitor can. This has nothing to do with the quality or correctness of my monitor, but more to do with the simple fact that there is some perceptual errors introduced by looking at something that is electronically transmitted.
So printing can be used as a kind of reference, to find discrepancies in the work so you can go back and work on ironing them out. The thing that is most surprising about this, is that if you are able to work on your images until they look great in print, they will also look great on the monitor also. But the same is not true the other way round.
If you really want to push your image editing forward and get the best out of your work. You really have to start printing it.
Just make sure that you have your monitor calibrated and profiled as best as you can get it (use a decent colorimeter for your monitor - X-rite i1 display pro for example), but even once you have calibrated and profiled your monitor, there is only one way to confirm that it is correct: that is to use proof print that is guaranteed to be close to the file it was printed from. I use Neil Barstow's ICC verification target. Once I have calibrated my monitor, I check it's accuracy by comparing the ICC verification target against the file it was created against. The target is placed under a daylight viewing booth such as my GTI viewer below, and I open up the file in Photoshop. I also ensure that the right ICC profile is selected and proofing is switched on. If there is a difference in the colours between my target and file on my monitor - then I need to redo the calibration. I often find that it is more about the colour temperature of my monitor. In the image below, you can see that my monitor is perhaps a little colder than the target is under the viewing booth. So I will turn the white point down of my monitor a little and reiterate the process until my monitor is very close to what I see on the target.
When you do print, let your gut tell you what's wrong with your work once you print it. If you notice that the tones aren't as punchy as you thought they were, then look again at the file on your monitor and I'll bet you that you will now notice that they indeed lack punch there also. Your monitor isn't the best reference for telling you how far you need to go with your edits: your prints are.