Do You Know Your File Formats?
If you’re in a creative profession or not, more than likely you have come across at least one of these formats. While creatives may be more used to seeing these formats, there are many different kinds, and some subtle differences that make each of them useful for their own purpose. Each file type was created for its own use, they can each perform the task, but some were designed specifically for a purpose, ie. to do it better than the others.
Image file formats are used in various places. On the web as icons or images, digital illustrations, for print – photography, high quality magazine, newspaper. But which format is the correct for each use, and which one should you use?
There are several formats, but each can be split into 2 types of image category; Raster and Vector.
Raster images (or Bitmap) are images based in pixel format. Using tiny dots, called a ‘dot matrix’ to create the image as a whole. Think of this as the atoms of an image. These are called ‘Pixels’. Pixels can not be stretched beyond the size that they are set at, and when pixels become bigger or are stretched beyond their maximum dimension, this is when an image becomes blurry and unclear. Have you ever tried making an image larger only to see that it blurs at bigger sizes, and you think “why is this happening?”. Raster images are practical for complex images containing minute details.
Vector images are images based on strokes and paths. This allows them to be easily resized to any dimension, unlike Raster images, which can only be rescaled smaller. For this reason, vector images are easier to work with and cleaner than Raster. Unlike Raster image, Vectors can never become blurry by enlarging them. They utilise smaller file sizes and offer crisp, clear detail at any level, making them the perfect category for logos and digitising lettering artwork. Vector images are practical for simple images using minimal shapes and colours.
Within these 2 categories, the formats reside. Whether you are a designer, an accountant, or someone who uses a smartphone. We all deal with image formats on a daily basis. Some of the most used formats which we deal with are;
JPG (Joint Photographic Experts Group) – Possibly the most widely used format in the digital age, it has become the standard for images to be produced, stored and shared. Generally used for large photographs, but can also be used for low resolution images on the web. JPG’s do not support transparency, which makes it ineffective for design asset usage such as animation, web design. JPG’s are raster type images and thus work with in pixels. The method in which JPG’s are saved, compresses the quality so as some pixels are lost each time it is saved. This is called ‘lossy compression’. For this reason JPG format is not practical for printing.
PNG (Portable Network Graphics) – PNG’s are widely used as logo files, and high quality digital assets. They are considered a lossless format, meaning unlike JPG’s, when you save PNG’s, they do not loss any quality, thus will not deteriorate after sending and downloading. This makes them perfect for transferring images in an online environment. PNG’s support transparency, which allows for a logo to have a clear background and can be used in a variety of situations (on websites etc.). They are used in animations, apps, and logos and other assets. PNG’s are not practical for printing, but offer crisper detail than JPG’s, combined with the support for transparency, makes it perfect for Logo.
GIF (Graphics Interchange Format) – Used mainly as a way to lower file sizes. It uses low colour counts, limiting the colours to 256 which drastically reduces file size. Making it perfect for storage. Used for basic, 1-tone colours on websites to dramatically reduce loading times on websites. Supports animation and also transparency. When you see a meme with moving elements, it will most like be a .GIF. But limiting its colours to such a scarce range, means it is far lower quality and not used for print. GIF is similar to PNG, but far lower quality.
PSD (Photoshop Document) – An original file format used for editing photos using layered graphics. Supports all graphic formats mentioned here and can them as individual layers. Meaning you can import multiple formats into a PSD to edit. PSD is editable and can utilise transparency, filters, and various effects. Cannot be scaled over its maximum dimension.
EPS (Encapsulated Postscript File) – A vector file format used in logos and illustrations, can be saved at any size and is perfect for large-scale printing. Not much support online means that you will not be able to upload these files to many websites/social media etc, because they normally carry a large file size. They can be scaled and edited to any size without losing quality. Also supports transparency and full colour, making it perfect for logos.
AI (Encapsulated Postscript File, Adobe Illustrator) – A layered, editable file developed by Adobe for illustrations and graphic design. The original file where vector based graphics are created. Supports EPS format.
PDF (Portable Document Format) – Possible the most used/shared file type in the digital age, especially in business. PDF’s are used to represent graphics or text independently of the software used to create them, meaning you get the exact colour, layout, and display regardless of what software you view it on. Everything is fixed into place when it’s exported. There is no loss of design or quality. Generally the best format for high quality printing.
This isn’t a list of all image file formats, just some of the most recognised and used formats in the industry. There are others, such as TIFF, BMP, SVG and more. Again, used in different creative fields and for different circumstance.
With these 2 categories mentioned, Raster and Vector, there is 1 convention that ties them together. Resolution. Refers to the size and clarity of an image. Often refers to the size of desktop or Smartphone screens and indicates the ‘Dots per Inch’ (DPI). There are 2 standards for DPI – ‘low res’ and ‘hi res’.
High resolution (300 DPI) is used for high quality printing and magazines.
Low Resolution (75 DPI) is used for screens and online, not for print.
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