Friday, July 16, 2010

Color management, calibration and saving photos for the web

If there's one photography subject that's complicated and confusing at first, it must be color management. It definitely kept me busy for a while. There are so many aspects that you need to understand and deal with, it can be quite overwhelming. But if you want to step it up a notch, you just can't get away from learning more about the fundamentals with regards to color spaces and color management. Even when you have mastered using your camera's white balance settings effectively, chances are that the recorded colors are not accurate. And on top of that, you can't rely on the colors being accurately displayed on your screen. Double trouble.

I'm not claiming to be a color management expert - I certainly have a lot more to learn when it comes to this subject myself. But I do believe that others can benefit from my experience with the tools that I've bought and how I use those to help me improve my color management work flow:

1) Photoshop CS4,
2) a Spyder3Xpress for monitor calibration and
3) the X-Rite ColorChecker passport system to ensure a correct white balance.

For the record, this website doesn't sell anything and I'm not being sponsored by the makers of the products I'm describing. This is simply a description of what I use and how I do it, nothing more, nothing less.

Monitor calibration

To be able to tell if the colors in your photos are seen as intended, it is essential that you work with a calibrated monitor. Managing to correctly display colors on your screen is one thing, things get even worse when you want to print your photos. Without color management procedures, the print will probably look nothing like what you see on your screen. That nice bright red may all of sudden be purple and what you thought was black turns out to be dark blue... Frustrating and expensive, especially if you've spent a lot of money on fine art paper and ink. But even if you only post photos on websites, others may see completely different colors compared to what you see on your monitor.

The first step is calibrating your monitor. Most operating systems have some software to help you do that and of course you may like to fiddle with your contrast, brightness and what buttons have you. But at best, you'll end up with settings that look pleasing to your eyes. That still doesn't mean that it will look the same on other screens, let alone in print. That just doesn't work, there are too many factors involved in getting it right.

Spyder3Express (picture by DataColor)


The answer to my own ongoing problems while trying to get it right was however as simple as can be. I got myself a Spyder3Express. It is a simple device that you position on your monitor and you run the included software to automatically generate a correct profile. The software also makes sure that the profile is loaded into your graphics adapter every time you boot up your system.

Spyder3Express is relatively cheap (I paid approximately 80 Euro), it's reliable and it will do the job for you without you having to spend time on the how and why of monitor calibration. Perfect, one problem solved. Certainly, but you do have to remember that the Spyder3Express will create a monitor profile given the then current conditions. For instance, the ambient light plays an important role in how colors are "seen" by the device. But if your working conditions are generally the same then a single profile will suffice. If not, e.g. when you last calibrated your screen at night and you need to edit your work during the day, then you may want to recalibrate before you start editing your photos. It only takes a few minutes, but it will make a huge difference.

Using the X-Rite ColorChecker

Before moving on to the next subject, it is essential that you shoot RAW and that you know how to work with the Camera Raw plugin for Photoshop. If you want to be in control of your colors, there's no alternative for shooting RAW. You may want to read Shooting RAW versus JPEG first.

My next purchase in order to get the colors right, was the X-Rite ColorChecker Passport. A fellow Paneristi advised me to get it and so I did. When I first received it I thought that I had paid about 100$ for a simple piece of plastic with a bunch of colored squares... I could have just printed a color card myself. I was wrong of course. Once I fully understood what it is and how to use it, it became a valuable part of my workflow and it's absolutely worth what you pay for it.

This picture shows 3 ColorCheckers and the CD that comes with it

ColorChecker Passport is actually a system that comes with software to create DNG (digital negative) profiles for Camera Raw (the Photoshop plug-in to convert RAW files). This may sound complicated at first, but using the ColorChecker is very simple and it really is an end-all solution to white balance problems.

Shooting with the ColorChecker tool

Once you have your lights set up and you are ready to start shooting, put the ColorChecker clearly visible in the scene and take a shot. Once you have done that, you can continute to shoot like you normally do. When you make changes to the lighting setup - e.g. when you move your lights or when you change the output power of your strobes - it is best to first shoot the ColorChecker again before you continue taking the rest of your shots.

Creating a profile with the ColorChecker software

When you start editing your RAW files, you first load the shot with the ColorChecker in it, into the software that comes with it. Simply start the software and drag the RAW file on its main window (see picture below).

X-rite ColorChecker Passport creating a profile
Creating a DNG profile with the ColorChecker software

The software will automatically find the color squares and you can check if it has done so correctly by looking at the green boxes that it draws (above). If everything is ok, you just click the Create Profile button. Save the profile with a name that indicates the shoot for which you have created it, because you'll have to select the profile by its name later on. On my system it takes about 5 seconds to create and save the profile.

X-rite ColorChecker Passport selecting the profile in Adobe Camera Raw
Applying your profile to a single file in Camera Raw (Photoshop)

Applying your camera profile to your RAW files

Now open the first file you want to edit in Camera Raw, and click the Camera Calibration icon on the right hand side (as shown in the above picture). The new profile that you created will automatically appear in the camera profile dropdown box - shown in the red oval in the screen shot. Select it and your done. Brilliant.

It would be time consuming if you would have to do this for every single file, but luckily you won't have to do that. You can apply the same profile to many files at once. Here's how to do it on a Windows machine. First make sure that Photoshop is running. Go to Windows explorer (Windows-key+E) and click the files you want while holding down the Ctrl-key on your keyboard. Now drag the RAW files onto Photoshop. The Camera Raw plugin will open and all your files are displayed on the left hand side. Select all the files by clicking the first one and then then the last one while holding down the Shift-key. Click the Camera calibration icon on the right and select the DNG profile that you created earlier. Finally click the Synchronize button on the top left and you're done.

X-rite ColorChecker Passport selecting the profile in Adobe Camera Raw
Applying your profile to multiple RAW files at once

Color spaces and saving files for the web

Explaining all there is to know about Color Spaces here would go beyond the scope of what I'm trying to explain. It is important to at least know that there are different Color Spaces and that the Color Space that you use must match your output. E.g. for a website or for a print. If you want in-depth information, then read this article explaining the Color Space fundamentals on Wikipedia.

To keep it simple, websites will display images using sRGB. Your file however is most likely Adobe RGB (check your camera's settings to be sure). The range of colors in Adobe RGB is so speak much wider than that of sRGB. As a result a web browser will convert your colors into something that's close to what the original file is like. The results are generally disappointing.

Luckily, Photoshop has a function built-in to optimize and convert your file to sRGB. I store my original files without converting them, because I don't want to limit myself in terms of what I can use the files for later. And so I create separate files that are for web use only. In Photoshop resize your image first, in the menu, choose Image, Image size or press Alt+Ctrl+i on Windows (see picture below).

Resizing the file

Photoshop resize dialog
The Photoshop resize dialog

In the resize dialog (above), make sure that the boxes Scale styles, Constrain Proportions and Resample Image are checked and that you have selected Bicubic as the resampling method. I generally resize files for web use to 1024 pixels on the longest side. There are many tools out there to resize images but trust me, nothing beats Photoshop when it comes to resampling files. Note that although the resolution for websites is 72 dpi, you won't have to change these settings when you resize your file. The Save for web function - which is described next - will automatically take care of this for you.

Saving a file for web use
Saving a file for the web

Saving for the web

Now that the file has the right size, choose File, Save for Web & Devices in the menu or press Alt+Shift+Ctrl+S (on Windows). The above dialog appears. I have put red circles where the most important settings are in the screen shot. On the top right be sure to select JPEG. Choose Very high as the quality option. Make sure to check the boxes Optimized and Convert to sRGB. At the bottom on the right select Bicubic - although this setting won't do anything if you leave the size settings alone which you should because you have already resized your file as described in the previous paragraph. I've just made it red to show that you can resize with this dialog too. Finally click the Save button to convert and save your file. Don't accidentally save your original file because you have resized it!


If you find this post helpful, if you have remarks, questions of anything to add - then please post a comment. Your feedback is appreciated.

© 2010 M.Wilmsen - do not copy without permission

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1 comment:

  1. Calibration
    Outstanding.I cant believe it.Honestly Great post.Thanks for sharing such away.Really informative.