Images in your email, Part 2
In our first Email Design Principles post, we went over the importance of alt text behind your images. In Part 2 we are going to review some technical considerations when choosing images for your email campaigns:
Resolution: Digital images are measured in DPI, that’s dots (also knows as pixels) per square inch. It isn’t enough to know how wide or tall an image is; you need to take DPI into consideration when choosing an appropriate image for your project. For an email or website, the appropriate setting is 72DPI, or seventy-two dots per square inch. Often, when you upload a tiny image at 72DPI, and try to enlarge it in your newsletter, you begin to see those pixels, and the quality of your image is less than desirable. This commonly known as “pixelation” or “the jaggies”. It’s always good practice to upload a larger image and then scale down, as scaling up never produces a good result. Also, remember that a photo that may look good in your email will not work so well in your printed materials, which should have a minimum resolution of 150DPI, with 300DPI being the optimal choice.
Images types: Again, email is behind the times, and the only two types of images you can really count on working consistently are JPEG, and GIF. There are pros and cons to both types. JPEGs can be compressed, reducing the time it takes to download and display the image in your email. However, compressing your image too much, and the quality can become so poor, that the image is barely readable. GIFs can have a transparent background, ideal for buttons and icons, but also generally have a larger file size. GIFs also have the ability to be animated, but again, an animated-GIF will not animate in your email. PNG images, which can also have transparent backgrounds when used on a website, will not be transparent in email, and should be avoided. They typically also have the largest file size. BMP, TIFF, EPS are other files types that will not display correctly in email, and are most often used in print.
File Size: Remember that each and every image you upload adds to the overall time it takes to download and display your email. It’s a constant dance, having your email look professional and visually impactful, while keeping the file sizes low / load times fast. One way to get around the file size issue is to take a very large image and “slice” it into smaller pieces, which will ultimately load faster.
Next: Images in your email, Part 3
