As many of you know, the forums for the National Association of Photoshop Professionals (NAPP), is a place that I really enjoy spending my spare time in. It’s an excellent resource for a number of reasons: first of all, I learn a lot! Second, some great questions come through there that get my brain going. Third, and most importantly, when I contribute to discussions in there, it often turns into some meaningful content I’ve created to help explain things. That content then becomes some very useful tools in creating – yup, blog posts for the readers out here in the non-NAPP world!
For instance, someone was asking in the NAPP forums about methods to ensure all their files are output to a minimum of 50 MB for delivery to a client. It was a great question with lots of useful contributions. I decided to throw my two cents in, with a few suggestions that not only supported those made by others, but also include some tangential information. My thoughts were that a client asking all images to be at least 50 MB suggested that the client doesn’t understand color very well…because different colors have different degrees of data to them. Translation? Some colors will produce larger inherent file sizes .
I ran a little test to help demonstrate this by taking some pictures. Since I really wanted to get a complete illustration I sought out to find scenes that were 100% red, 100% green and 100% blue. Naturally, I didn’t have a lot of luck in the real world, but I could produce them easily enough in Photoshop. So, here’s what I did:
1. Created a new document, 800px square, and filled the background with a pure red, green and blue:
2. On each new fill, I pointed my camera at the monitor (which is calibrated every two weeks*), and took a picture. Here’s some screen shots of what the histograms looked like on the back of my camera LCD:
As you can tell, the histograms show that the colors are pretty spot on to where their anticipated locations should be…if you read the details below the histograms, you’ll also notice the amount of data that was in each image, but to make sure I was reading the data correctly…
3. I then copied the files to the computer, and without any editing on white balance or anything, looked at the file sizes. The results were pretty interesting:
So, the color blue will result in a larger file size than red and green carries more than blue. I also noticed that each color was successively brighter, which supports my understanding that more light in a scene also produces more data. Since some colors are inherently “brighter” than others on the color wheel, they will also naturally have more light.
It was an interesting test/exercise to illustrate that different colors carry different amounts of data. This also ties into the theory of “exposing for highlights and developing for shadows”. It makes sense…because more data is available from brighter colors and less data is available in darkness.
*Finally, it bears mentioning that I do have a rather envious setup – you see I was given permission to paint the office any color I wanted recently. I chose an 18% gray. The office was then lit with a daylight balanced bulb from one desk lamp, and the window is normally covered with a black felt. This, when combined with a calibrated monitor, profiled paper makes for a pretty good environment in ensuring color accuracy. This little “color test” for someone else also was a good test for the office environment, and the results there were pleasing indeed.
This post has gone on much longer than I had anticipated, but it was a great chance to expand a little bit on a couple of topics:
1 – What happens with color in your pictures.
2 – How that impacts your file storage needs and requirements for clients
3 – The importance of working in a good color managed environment
If anyone has any questions, comments, or input of their own on the subject, please feel free to share your thoughts with me via the comments section or via email. Happy shooting, and we’ll see you back here tomorrow!