Getting “It” Right For Better Photographs: Color Space

What do I mean by “color space” and why should you care?

Your monitor is the primary device you rely on to show you the colors of your photographs or other artwork on your computer. Today’s monitors are primarily flat screens and may use various technologies for displaying images (this sounds suspiciously like the beginning of the last “Getting ‘It’ Right” entry, doesn’t it?).

The color space, in fairly simple terms, is how many colors are available and how many can actually be shown on the monitor or the printed image.

Your eye can see billions of colors but a typical 8-bit image can contain 2⁸ colors per each of the three channels, or a maximum of 16.7 million colors. That’s a lot of colors. I don’t want to get into a deep discussion on color theory because I’d like to keep this on a basic level.

The bad news is that a typical 8-bit monitor can’t see anywhere near 16.7 million colors. Nor can a typical inkjet printer reproduce them. Although a good printer can reproduce more colors than a monitor, the colors are different.

Let’s talk about monitors for a minute…

Back in the olden days when color specs were being defined, a standard called “sRGB” was created to cover what could be reproduced on monitors of the day. This was (and still is) the standard for image viewing on monitors and the internet. An sRGB image should look the same (or at least similar) on monitors that are correctly profiled. This should be true in most applications and all web browsers without any need for additional color management. sRGB color space is also used for many digital cameras (when creating jpeg images) and is required by many print labs using chemicals to process their images.

In the late 90s, Adobe came up with a new standard that expanded the color space to include what could be reproduced on more up-to-date monitors and the better color inkjet printers. They called this “Adobe RGB(1998)”. This is still the color space of choice today for most commercial and fine art inkjet printing. Some of today’s 10-bit and higher monitors can display most, if not all of this color space.

Today, some people use an even larger color space called “ProPhoto.” However, you can’t see all of the ProPhoto colors on any printer or on most monitors (maybe on a 32-bit monitor, but there aren’t very many of those and I don’t know anyone who can afford one).

By the way, most good digital cameras will produce jpeg images using either Adobe RGB(1998) or sRGB. My preference is to shoot RAW and to apply the color space I need to use for each image on an “as-required” basis.

Knowing this, and hopefully not too confused, let’s try to simplify the process. If you stick to the following rules, you’ll be okay.

If your aim is to make prints on a giclée or inkjet printer - use Adobe RGB(1998) for your working color space. Do not use Adobe RGB(1998) for the internet - your images will look horrible (or at the least different from what you intend). This is because of how sRGB interprets colors that are not within its gamut (or range of colors).

If you are going to use the images for Powerpoint or similar presentations, on the internet, or for printing at a color lab - use sRGB. You can use sRGB for images you’ll be printing on an inkjet printer but they might not look as good as those you’ve printed based on Adobe RGB(1998).

What about ProPhoto? Well, for right now I just want you to be aware that it exists.

How do you specify the color space? In Photoshop, go to ”Edit > Color Settings...” and set your RGB color space preference. Photoshop will ask you what it should do when you try to open an image with a different color space.

How do you change an image’s color space? In Photoshop, go to “Edit > Convert To Profile...” and chose your new color space. Photoshop’s “Save For Web & Devices” also has a check box for converting to sRGB since that action is intended for images destined for the internet.

Oh, by the way, you can convert from a larger color space to a smaller one as needed (Adobe RGB(1998) to sRGB). But you can’t go the other way and expect to pick up any of the colors in the larger color space.

Our next step will be to learn about “printer profiles” and how to use them. It’s really not as intimidating as it sounds and we’ll cover it next time.

You can add your comments and questions below.  I’ll be happy to answer them. The idea is to just enjoy and learn.

iPhone Geolocation

There’s been quite a bit of interest recently about using a GPS device to track where you’ve shot photographs - this is called geolocation. There are many devices on the market that will do this for you... at a price.

How would you like to be able to geolocate for free - or almost free? You can if you have an iPhone or other smart phone that can use apps.

All you need to do is to find an appropriate GPS tracker and activate it when you’re taking pictures. Then you transfer the GPS data to your computer and use a program on your computer (there are free ones available for that too) to associate the time that you made your image with the location in the GPS data. These programs will put the location into your image’s metadata.

There are several programs that will read the metadata and show you a map, hi-lighting the point where you shot your image. I use Adobe Lightroom - it automatically opens Google Maps on my web browser.

for the original tracking, I'm using a free iPhone app (GPS Stone - from the AppStore -  on the iPhone and a free geocoding software package, GPSPhotoLinker - http://www.earlyinnovations.com/gpsphotolinker) for the Mac.

There are others available for windows - use google to find them.

It takes a little getting used to but it's been working reliably for the past few weeks. It is pretty accurate within a few yards. You can then use Lightroom or GpsPhotoLinker to display the photo's location on Google Maps.

One of the neat things about GPS Stone is that it can be set to record at various intervals in both time and distance. It also can be set to automatically resume recording after a phone call or activating another app (the iPhone OS only allows one app to run at a time). To get the data from your iPhone to your computer, simply email the .gpx track file to yourself - that's not automatic - you have to push a button.

GPSPhotoLinker is very fast and easy to use. Drag the images into the application from the computer or from Lightroom - copy the images to your HD first - don't do it from the CF card because this program will write directly to the metadata in the image files. This way you keep your original files intact if you mess things up.

You can view your position directly from GPSPhotolinker or from Lightroom. If you have imported your images into Lightroom prior to geocoding, you must read the updated metadata from the file (Metadata > Read Metadata From File) after running GPSPhotoLinker. Then you can click on the arrow next to the geolocation metadata (Library mode) to see the image location on Google Maps.

There is one caveat - you must have cell service to use GPS on a smart phone. It does work with ATT’s E network as well as with the G3 service. It just takes a little longer to initiate.

I’m planning on creating a video screencast of the process soon - keep checking here.