JPG, GIF, PDF, AI, etc. There’s so many to choose from! How do you know if you’re using the right one?
Before we get into the details, you should know the difference between Raster and Vector images and Lossy and Lossless image compression.
Raster images are made up of pixels and most often used for photographs. Your camera saves photographs as raster images. Photo editors (such as Adobe Photoshop and Adobe Lightroom) are raster based.
Say you have a JPG that’s 8”x10” at 300 dpi. You save it down to be 6”x5” at 300dpi. You can’t take that smaller image and make it an 8”x10” at 300 dpi again. You’d have to go back to your original larger image.
Vector images are made up of paths (not pixels). Instead of separate blocks of color, vector images rely on mathematical coordinates. They do not suffer from loss of quality no matter how much you change the size. Whether it’s scaled down to fit on your letterhead or enlarged for a billboard, the image will appear exactly the same. Illustration programs such as Adobe Illustrator create vector images.
Say you have an Adobe Illustrator version of your logo that’s 4”x4”. You need it to be 2”x2” on your business cards. You can take that same 2”x2” logo and scale it up to put on a vehicle wrap for your car. You won’t lose any quality.
Lossless and lossy compression describe whether or not, when a file is compressed (made smaller), all original data can be recovered when the file is uncompressed. Lossless compression retains all the data that was originally in the file when uncompressed. Lossy compression does NOT retain all the data. Once you use a lossy form of compression when saving your file, some data is lost and will never come back.
Raster File Formats
You most likely shoot in JPG or RAW. But do you know the main differences in these file formats? JPG is a lossy form of compression and RAW is lossless.
JPG is a lossy form of compression. If you’re shooting in JPG, your camera takes each image and discards some of the information it doesn’t think you need. Why? To make the file size smaller. Which means you can fit more images on your memory card and your computer.
You can also control the amount of compression in your camera’s settings. The more it’s compressed, the lower quality your image is going to be and the file size will be smaller. If you decide to shoot in JPG, edit copies of your original file, not the original.
RAW doesn’t compress your images. If you’re shooting in RAW, your camera takes each image and saves every little bit of information it can, even things you probably can’t see with your eyes. Your files are going to be much larger and will take up more room on your memory card and your computer. But you’ll have more information and more control over the editing process.
PSD doesn’t compress images. To preserve all Photoshop features (layers, effects, masks, and so on), save a copy of your image in Photoshop format (PSD). PSD documents support files up to 2 GB in size.
Note: I usually work in my PSD files and save out a flattened TIFF to place in other applications or send to printers/designers. I will convert my TIFF files to CMYK (if needed) and leave the PSD in RGB. Some people prefer to work in a layered TIFF, and that seems to be fine too.
PNG is a lossless form of compression and great for images on the web. PNG supports 24‑bit images and produces background transparency without jagged edges; however, some web browsers may not support PNG images. PNG-8 has a maximum of 256 colors and PNG-24 can have millions of colors. PNGs are great for icons.
TIFF can be either uncompressed or compressed using lossless compression. TIFF is supported by almost all image-editing and page-layout applications. TIFF documents have a maximum file size of 4 GB. It also supports transparency.
GIF uses a lossless form of compression. However, a standard GIF image can only include a maximum of 256 colors. Use a GIF when your graphic has a limited number of colors, hard shapes, large areas of solid color or is transparent. You can also use it to save animations (which you’ve seen all over the internet). It’s a pretty old image format and is usually only used to create animated GIFs now. GIF is not suitable for saving photographs.
BMP is lossless. BMP is a standard Windows image format on Windows-compatible computers. There’s really no benefit to using BMP over TIFF. It’s an older image format left over from the early days of computer graphics.
Vector File Formats
AI is a proprietary file extension for Adobe Illustrator vector graphics. Your logo was probably created in Adobe Illustrator and started out as an .ai file. This format can be easily edited by anyone else that has Adobe Illustrator. This version of your logo can be scaled up to any size without losing quality.
PDF is a file format used to present and exchange documents reliably, independent of software, hardware, or operating system. PDFs can contain links and buttons, form fields, audio, and video. They can also be signed electronically, password protected and are easily viewed using free Acrobat Reader DC software. You can send a high-quality PDF to most commercial printers. You can even save Adobe Illustrator files as PDFs that will be editable in Illustrator.
If you want to get really in-depth about all the different settings of a PDF, I recommend this article by Adobe:
EPS is generally used by a vector graphics program such as Adobe Illustrator. It’s what early versions of the AI format looked like. It’s also an older file format and these days doesn’t do anything that a PDF can’t do.
SVG is a Scalable Vector Graphics file. Website graphics are often built in this format, so they can be resized to fit different designs in the future. They can be useful as web designs are becoming more responsive.
Note: Just because someone has saved a file as an EPS or AI doesn’t automatically make it vector. I can’t count how many times I’ve asked someone for a vector version of their logo only to receive an AI file that has had a JPG placed into it and saved.
If you have Adobe Illustrator and you’re not sure if the file is vector or raster, here’s an easy way to check. Use the key command “Command + Y”. This will show your artwork in outlines mode. If all you see is a box with a thin black line around it, your image is raster. If you can see the whole outline of your logo, your image is vector.