(Almost) everything you need to know about colour
Colour shouldn’t be hard. All you want is
- Your pictures to look like they do in real life
- Your prints to match your screen
- Your pictures to look fabulous when you post them to the web or take them round a mate’s house
Sit back, relax. Take a deep breath. This isn’t going to be hard. To keep this to a simple article I’m not going to go into the depths of colour management and explain exactly why you need to do some of these things. There are plenty of articles that explain that on the web and you can read whole books on it. I’m going to say what you need to do to get things sorted. Think of it like a car – I’m not going to spend ages talking about oil viscosity and duty cycles and operating temperatures. I’m going to say “stick x litres of Magnatec in and check and top up every fortnight”.
There are 4 variables we are going to look at: these are white balance, camera colour space, monitor profile and output profile. That might sound like a lot of techie stuff but as promised we are going to take shortcuts.
White balance
Take a look at this picture.
daylight
This is based on an example shown to me by Damian Lovegrove on one of his lighting courses. That’s a piece of white card folded in the middle. The left side is illuminated with daylight and the right has a normal tungsten light shining on it. White balance on the camera is set to daylight so the tungsten side is yellow.
tungsten
Here’s the same shot with white balance set to tungsten – the daylight side is blue. That’s a pretty graphic example of how much the “wrong” white balance can affect your pictures.
[Picture1 is also rather underexposed because the tungsten light was a lot brighter than the early morning light on a dull day – if I exposed correctly for the daylight everything went white.]
Rule 1: set the white balance correctly on your camera
The manual will have details of how to set custom white balance but it doesn’t need to be that hard. If it’s sunny then point the whibal at “sun”. If it’s tungsten light then point it at the little lightbulb. That will get you the right answer 90% of the time when there is one. Notice that there’s sometimes no right answer – no white balance will make the card white in both those light sources. Sometimes you just have to give up and accept that you will not be able to reproduce the correct colour (or rather that you need to change the lighting…).
Camera colour space
Another great opportunity to dip into your manual. Cameras generally have a choice of 2 colour spaces (many of them only have 1 in which case just skip this section). These are almost always Adobe 1998 and sRGB. Pages and pages of words and diagrams have been created on this and there are lots of good arguments – but this is the simple version. So here’s the deal.
Rule 2: set your camera to sRGB
Some people have special reasons for using Adobe 1998 ad that’s fine (though they need to read the bit on output profiles carefully) but if you’re not sure then use sRGB.
Monitor profile
Go down to Dixons (or Currys: Direct as they like to be called) and look at the TVs there. Chance are that they are all showing the same program but all the colours look different. Which one is right? If I buy a Sony and you buy a JVC then what are the chances the colours on our tellies will match? Pretty slim. Looking closely even the same brand and model is subtly different from the one next to it. Which brings us neatly to…
Rule 3: calibrate your monitor
Calibrating your monitor makes it look like mine. It also looks like any other calibrated monitor in the world (within hardware tolerances) and looks pretty much like the ones used by the guys who wrote your printer profiles. If they can get a print to match their screen and you get your screen to match there’s then you are halfway to getting your prints to match your screen. If you don’t calibrate your screen then you haven’t a hope of getting it right.
There are a bunch of ways of doing this from the free to the very expensive.
One obvious way to do it is put your monitor next to a calibrated one and twiddle with the controls. As crazy as that sounds it will get you in the ballpark. However, monitors are imperfect devices – when the computer tells it to produce “red” each monitor produces a subtly different shade of red.
An ICC profile sorts this out. Think of it as an interference pattern – when the computer says “red” the monitor produces something slightly too blue. The ICC profile sits in between and actually changes the command from the computer. It tells it to add yellow (which is the same as reducing blue) and so produce the red we wanted in the first place. The only trick is creating them.
By far the easiest way to create an accurate profile is to use a hardware calibrator. This puts patches of colour on the screen, measures them and works out the difference. The difference is an ICC profile which it then assigns to your monitor. If you’re in the market for a budget calibrator then check out the Pantone Huey which is relatively cheap and very easy to use.
If you want to save some money then you can calibrate your screen by eye. If you’re on a Mac then you’ll learn why lots of graphics pros use them – colour calibration is built in. Go to System preferences…displays…colour and press the calibrate button. It will walk you through the process.
If you’re on a PC and have Photoshop then you need to run Adobe Gamma. If you don’t have it then your best bet is probably one of the online calibrations wizards such as this.
Output profile
OK, we got to the last section without it getting too techie. Unfortunately this is where it can get hard – but only for your own printers. I’ll break this down into 3 different areas that should cover all your output needs.
Web use
The web works in sRGB colour space. A small number of browsers are smart enough to work with other colour spaces but most assume that all pictures are presented to them in sRGB. They don’t even check. If you post a picture in 1998 to the web then it will look flat, dull and horrid.
Rule 4.1: For web output make sure your image is in sRGB
If you followed rule 2 then you’re halfway there – you just need to check. If you are working in Adobe 1998 then you’ll need to convert the picture to sRGB (and make sure you read bonus rule 5!).
If you are using Photoshop Elements then go into Image…Convert Color Profile and look at the options. If “Apply sRGB Profile” is greyed out then your picture is in sRGB. Otherwise select it to convert your picture to sRGB. In Photoshop go into Edit…convert color profile and if the source space isn’t sRGB (or sRGB IEC61966-2.1 to give it its full name) then select that as the destination space.
A lab print
Call up the lab and ask them what colour space they expect files in. If they don’t know then the answer will be sRGB (though consider getting a new lab…). Traditionally printing was always done in Adobe 1998 but practically all mini labs now expect files in sRGB. They convert them internally to their printer profile but need to know where they are starting from. Some labs will provide custom profiles of their own particular machines and you can get more predictable results by converting to this profile just before sending the file to the lab but you should only do this if you are happy dealing with ICM profiles. They will be able to convert from a known colour space to their own profile for you.
Rule 4.2: For a lab use either their recommended colour space or sRGB if they can’t answer the question
See the bit on web output for how to convert to sRGB.
Your home inkjet printer
OK we saved the hardest for last. Remember I said that the lab will convert a known profile to their printer’s profile? For a great inkjet print you need to do all of that yourself. Photoshop Elements makes it easy for you. In the print dialogue select “more options” and look down at the bottom. The source space should be “sRGB” (if you’ve followed my advice). In the printer profile select the correct profile for your printer/paper/ink combination. This is actually the next rule.
Rule 4.3: Always print using the correct profile for your printer/paper/ink
When you buy a printer it should come with profiles (these will be on the install disk). There will be a number one for each paper type. It should be as easy as selecting “Epson Glossy Photo Paper”. Sometimes these have confusing names – you will need to look up in the manual or on the web which profile goes with which paper. In full Photoshop you need to do a print with preview to get all the colour options. In both packages set the rendering intent to “perceptual”.
You can also buy commercial profiles or some expensive hardware and make your own but that’s far beyond the scope of this article. The canned profiles for your printer should give acceptable results as long as you follow these guidelines:
- Follow all the other rules in this article!
- Use the correct ink – 3rd party inks may not match the profiles correctly
- Never let the printer do the colour conversion – always do it in the “more options” box
- If you’re using “full” Photoshop then always use print with preview rather than print so that you get the colour options
Final word
So there we go, you should be getting great images on your screen, on the web, from your lab and from your inkjet. And we did all that without even explaining what a colour space actually is….
Once you get confident with colour feel free to disregard the advice in this article – I’ve tried to keep everything as simple as possible. It’s possible you can get even better results by tweaking them but try riding with the stabilisers for a bit and see if you like it.
Oh yes, one more thing.
Bonus Rule 5: Never use “assign” profile – always use convert
In Photoshop there’s an option for assigning a colour space to a file (as opposed to converting it which is what we’ve been doing). Don’t use it. That’s pretty well the same as highlighting some text in this article and in Word changing the language to French. It won’t translate it but it will confuse the spell checker no end…
technorati tags:photography, digital, color, output, profile, colour, space, WB, white-balance
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