E-mail etiquette in the new age of imaging
(reading time 4 minutes)
Have you ever sat for 10 minutes waiting for one e-mail to get from your Internet mailbox to your desktop? And then when it finally comes in, you download it to the desktop and double click it and the image fills 4 computer screens and seems bigger than the Grand Canyon?
Several forces are conspiring against you. The Internet is in fact slow at times. But more to the point lots of people are getting scanners and digital cameras. If these users are not vigilant they run the inadvertant risk of taking a fast efficient massaging system and turning it into a slow image delivery system.
When E-mail was originally designed, Internet speeds were very slow, there was not much capacity and graphic user interfaces like Windows and Macintosh had not yet been designed. All messages sent were just that, messages. A few lines of simple type were the most efficient way to move information from one side of the world to the other. Because they were only 1 or 2k in size (that's smaller than a flea on the tail of a dog in relative terms) the messages moved quickly even with the limits of the Internet. And because they were simple type (sometimes referred as ASCII Text) they were readable by all.
As users became used to the idea of a graphic environment their expectations grew and e-mail clients (like Outlook Express, Communicator or the many web based mail systems) added the ability to spruce up their e-mails...first with typeface variations and size, and then, with graphics, HTML, images and other enhancements.
Typeface variation and even advanced formatting add a small amount of size to any e-mail but with the higher capacity of the Internet and faster computers this is hardly noticeable. It's that JPEG photo enclosure that's causing the messages to come in so slowly. A straight text message is about 1k (1000 characters (footnote 1) ) in size, a formatted e-mail might be 10 K (10,000 characters). With a juicy JPEG attached if you aren't careful the message will balloon to 500k in size and literally take 10 minutes to get to you from your service provider. If your correspondent includes 2 photos or perhaps even 3 the problem multiplies very quickly. When the Internet gets still faster and we all have high speed access this might not be a problem but for the near term everybody's e-mail goes significantly slower when this happens.
What is a JPEG (2) and why should you care?
A JPEG is the file format for the image that you scanned with your scanner, downloaded from the Internet or saved with your digital camera. You may have noticed its .jpg ending on the file name. It is the standard file that is used for continuous tone (life like) images. It is in wide use because it is flexible, retains a great deal of the original quality and allows for the information in the file to compressed (squeezed) so as to take up less space.
How to make the perfect JPEG
The ideal .jpg file to receive via e-mail is one that is small (less than 50k) and fills just part of your screen. The two things that you need to be concerned with to avoid problems in these areas are the size of the JPEG in pixels (dots of colored information in the image) and the amount of JPEG compression that you have used.
A typical computer screen has a resolution of 800 x 600. That means that the screen can display 800 pixels of information wide and 600 pixels high. What happens if someone sends you an image that is 1600 x 1200 pixels? With the typical computer application it would show one quarter of the image on your screen at a time. How did it get so big? The image probably started out as a 4x6 in. snapshot. It was placed on the new 300 ppi scanner and scanned at 300 pixels per inch (ok I'll do the math..4 in x 300 pixels per inch = 1200 pixels and 6 in. x 300 pixels per inch = 1800 pixels). Perhaps they just bought a new 2 megapixel digital camera and set it on it's best setting and again achieved a similar (1600x1200 pixel) oversized file.
More is better with some things, but not pixels; "just enough" is the order of the day. Or rather, just enough for the medium in which the image is to be viewed. To have avoided this scenario the sender needed to scan at 72 dpi, set their camera at a lower resolution, or resized their image, in an image editing program like Adobe Photo Deluxe, Microsoft Photo Paint or Paintshop Pro. Are there times when more pixels are better? Yes but not in e-mail images.
Now on to compression. The JPEG file format standard defines a way to throw away information from an image that is to be later reconstituted. This is known as "lossy" compression. It's kind of like instant mashed potatoes in that content is removed for later insertion (although personally I think that the impact of JPEG technology on a photo image qaulity is vastly superior to the impact of dehydation technology on the flavor of potatoes. With JPEG technology you only ruin the image if you want to). JPEG compression can squeeze an image as little as 2 or 3 times smaller to as much as 15 to 20 times smaller. If you are just e-mailing an image then by all means squeeze away. An image that starts out life as an 800x600 pixel image will be 1.6 mbytes big. When compressed using JPEG at a 5x ratio it becomes 332k. You could squeeze this same image down to about 22kb and it would still look ok (not as good as the 332k file but good enough to allow you to appreciate the image).
Sending the occasional small image via e-mail can certainly enhance your e-mail message. Images usually tell a more compelling story, however when there are a number of them. Enclosing more than one image in an e-mail might be considered by some roughly akin to home movies. A powerful new alternative technology for sharing photos is the new web based photo sharing sites.
