RASTER & VECTOR: TWO CLASSES OF DESIGN FILES
RASTER FILES are made up of tiny dots called pixels. The number of pixels in this type of file remains constant, so if you try to make a raster image bigger, the pixels become more visible, thus appearing ‘pixelated’ or blurry. When using a raster file, it is important to get a photo that is of sufficient size, measured in pixels, for your needs.
Common raster file formats:
Best for: Web design, on-screen and for home/office applications such as Word or PowerPoint. Digital photographs typically originate in JPG format. JPG files are smaller than some other raster formats due to compression. Be aware that each time you open, edit and resave a JPG file, it further compresses the file which results in a loss in quality each time it is saved. Large format tips: You can use JPG files in large format projects, but they need to be photographed with a sufficient number pixels and adjusted in design software to the ideal print settings.
Best for: Web or on-screen images that contain large areas of uniform colour and fewer than 256 colors. GIF files are small, prone to pixelization and do not resize well. Large format tips: GIF files are not typically used in large format design.
Best for: Web or on-screen images. The BMP format stores colour information for every single pixel. While all this information means they can represent beautiful images, BMPs are very large and do not scale up or down well. Large format tips: BMP files are not typically used in large format design.
Best for: Web or on-screen images. PNG files are superior to GIFs because they support millions of colours while offering small file sizes. While PNG is a newer format, it is now supported by the majority of web browsers. Large format tips: PNG files are not typically used in large format design.
Best for: Professional printing, high quality images. This format creates large file sizes, but unlike JPGs, TIF files do not lose information when edited and saved. Large format tips: As long as the image is created with enough pixels, this is an excellent format for large format design.
Best for: A relatively new format often used by professional digital photographers. Generally, this format is used for in-camera storage and files need to be converted to JPG, TIF or PSD once the photographer transfers them to a computer. Large format tips: As long as the image is created with enough pixels, this is an excellent format for large format design. It must first be converted to a usable format using design software.
Best for: Professional designers who need to edit or prepare an image for high quality printing. PSD is the proprietary file format of Adobe Photoshop, and allows designers to create complex images using a multitude of layers. You must have Adobe Photoshop in order to open a PSD file. Large format tips: As long as the image is created with enough pixels, this is an excellent format for large format design.
VECTOR FILES are made up of mathematically-defined lines, objects and fills. They can only be created using illustration design software such as Adobe Illustrator. The huge benefit of vector files is that they can be scaled from the size of a postage stamp up to the size of a house--while maintaining quality. Additionally, specific colours (i.e., Pantones) can be used in the design. This makes vector files excellent for logo design. While raster items (e.g., photos, or a raster version of a logo) can be opened by illustration software, that item will never have the same scaling attributes of a vector file. Unless an item is actually created in an illustration based program, it cannot be simply 'saved as' a vector file. In order to view and edit an vector file, you will require illustration based software. It is always best to keep a safe copy of the original vector file on hand in case it is needed for edits or printing in the future. Consider this the ‘master copy’ of your logo.
Common vector file formats:
Best for: Graphic designers creating or editing logos, digital illustrations and for professional printers. AI is the proprietary file format of Adobe Illustrator and can only be opened using that program. Large format tips: Excellent format for use in large format design as it can be scalable to whatever size you’d like! When sending an AI file that contains text to a printer, be sure to save a master copy of the file. On the copy your are sending, convert the text to outlines, so there is no change to your selected fonts.
Best for: Graphic designers creating or editing logos, digital illustrations and for professional printers. EPS is considered to be the universally accepted vector format. Large format tips: Excellent format for use in large format design as it can be scalable to whatever size you’d like! When sending an EPS file that contains text to a printer, be sure to save a master copy of the file. On the copy your are sending, convert the text to outlines, so there is no change to your selected fonts.
PUTTING THEM ALL TOGETHER:
Graphic designers use Adobe InDesign (INDD files) and / or Quark Xpress (QXD files) software to assemble logos, images and text into your poster, sign or banner. Once everything is finalized, they can send those files to the printer packaged with all of the components used, or they can create a press-ready file called a PDF which assembles everything into one document and makes it ready for print. This format can be viewed by virtually anyone on any computer platform. A PDF cannot be edited however, so you must return to the original creation software to make any changes.
Knowing the different types of file formats can be handy when you need an image or logo for a specific project. Understanding that some formats are better at some things than others will ensure your final product looks as great as you intended!
© Cathy Vandergeest, RGD, gawck group inc.