At our newspaper and magazine, as well as at home, a lot of images pass through my hands, including a lot of images that are emailed to me. Much of the time the images are correctly formatted and pretty much ready to use, but we still get a fair number of images that are mishandled and need to be fixed, or which either won’t “go through” when emailed or take a longer-than-neccessary amount of time to go through. So here are some tips for sending photos via email, either to us for publication or to your friends and families.
- The best file format for your emailed photos is JPEG. “JPEG” is an acronym for the Joint Photographic Experts Group which created the standard. This format is ideal because it is ubiquitous, meaning every computer in the world built in the last 20 years has a way to read it, and virtually all imaging software can utilize the JPEG. This format allows you to use compression to create computer files that are smaller without having to resize or resample your image. For example, you can take an image file from a 10 megapixel camera, leave the resolution at 10 megapixels, yet create a file for emailing that is just one megabyte or even less. It’s done when saving the file; in Adobe Photoshop, for example, when you use the File>Save as… dialog, the program will ask you to enter a quality value from 0 to 12, and will even tell you how big the resulting file will be. It’s perfectly safe and acceptable to create email image files at quality values of 3 or 4, since the original file will stay on your hard drive anyway. Values lower than that tend to produce excessive compression which results in what are called JPEG artifacts. (Side note: all the images you see in this blog, and most of the images you see on the internet, are JPEGs.)
- That said, don’t resize your images. In particular, don’t use your camera’s “email” setting for images you intend to send, and don’t use your imaging software’s “email” setting. These settings were optimized to send tiny images, for internet speeds from 15 years ago, when dial-up was all anyone had. These images are much too small to be of any use in any publication.
- One of the worst choices for emailing is the TIFF file, since it is typically the largest computer file that can represent your photo. For example, a TIFF from a 10 megapixel camera will be about 30 megabytes. Many email systems will reject a TIFF file, or any file, this large. TIFFs have many valid applications, and we use them all the time at the printing end of production, as the files we actually send be printed in our newspaper.
- Once in a while we get images emailed to us that have been converted to CMYK. Normally your camera makes images out of the three colors of it’s sensors, red, green and blue. This creates an RGB image file, and it contains all the color information recorded by your camera. Converting a file to CMYK (cyan, magenta, yellow, and black) is the very last step you should do prior to printing a photo or page, since your CMYK profile is designed to discard all the colors that can’t be correctly produced with the inks available to your printer. The resulting file has less color information than the original photograph, but since it describes four colors (CMY and K) instead of three (RG and B), the file is actually 25% larger. Also, unless you know the color profile of the printer where you are emailing the photo, you have no way of creating a valid CMYK profile.
- Some people combine multiple photos into a single package using .zip compression software, and while this does create an overall reduction in email file size, it’s possible that the email recipient might not be able to “unzip” your zip file. It’s better to send two, three, or four emails with just a few JPEGs in them than try to cram it all into a .zip file that might not work on the other end.
- Often photos sent to us contain large empty areas that are going to be cropped out anyway. (It never ceases to amaze me how many expensive pixels are cropped out of photos every day, in another irony of the megapixel chase). It would probably help reduce your file size if you would crop out all that sky and all that grass from your softball regional championship group photo. Our readers already know what sky and grass look like.
- The worst thing of all you can do with your digital image files is to print them out and bring them in to our newspaper or magazine for us to scan to turn them into digital image files. I know that sounds ridiculous, but we see it every day. It’s a little like getting four quarters for a dollar so you can use your quarters to buy a dollar bill, except that with an image, you lose a bunch of quality when you scan a print.
This entry seems to cover the basics of what everyone who uses computers for imaging should know, yet many people still don’t. The bottom line is this: email un-resized, compressed, cropped RGB JPEG files.