Logo Guidelines

Explanation of file formats

Vector vs. Raster

There are basically two different kinds of digita

What is a GIF

GIF, which stands for Graphics Interchange Format, are very internet-compatible because of their small file size and ability to contain transparent areas. GIF’s are almost exclusively used for the web where they are the best format for images with few colors such as buttons, icons, and horizontal rules in html documents. Do NOT use them for print.

Disadvantages of GIFS

There are problems with GIFs. They are limited to a palette of 256 colors or less. Thus for hi-resolution (print) images with lots of colors, another format such as JPEG or TIFF might be better.

JPEG

What is a JPEG ?

The name JPEG (pronounced "jay-peg") indicates a means of compressing an image file or making it smaller. JPEG stands for Joint Photographic Experts Group, the original name of the committee that wrote the standard. JPEG files will often contain .jpg or .jpeg in their names. It is the best format for any image with many colors such as paintings, photographs, and textures. JPEG allows levels of compression and decompression to be manipulated by adjusting quality settings. In addition using JPEG allows the storage of pictures at a much higher color resolution. This allows for greater accuracy and better looking images.

Problems of JPEG

One of the problems with JPEG is that it is a "lossy (loss of information)" compression format. If you begin with a raw image format such as a TIFF or BMP, all of the digital information exists. However, when you compress the information using JPEG, some of the information is lost. When the picture is reconstructed, the decompression approximates what the original picture contained. Usually this can be quite good. However, sometimes pictures experience "artifacting" where sharp edges become jagged and smooth textures start looking ragged. The best way around this is to increase the compression quality when you convert the original image.

Recommendations

Use JPEG for compressing large pictures that are originally scanned as TIFFs or BMPs. Don't use JPEG for compressing line drawings (images with few colors); instead, use GIF or PNG.

If your viewing software doesn't support JPEG directly, you'll have to convert JPEG to some other format for viewing or manipulating images. Even with a JPEG-capable viewer, it takes longer to decode and view a JPEG image than to view an image of a simpler format such as GIF

TIFF

The Tagged Image File Format or TIFF also makes image files smaller by compressing them, and also uses lossy compression. However a TIFFs quality is not as compromised as it would be using JPEG compression. A TIFF can be a relatively small file, yet still print in high resolution.

EPS

An EPS file or Encapsulated Postscript file, uses the Postcript printer language developed by Adobe. EPS graphics can only be printed well when the printer also speaks the Postscript language. An EPS offers no compression and is usually a larger file.