Most Common File Formats

EPS

A vector file requiring PostScript language to draw its image. You must have a specific software application to create an EPS file, such as Adobe Photoshop, Adobe Illustrator and QuarkXpress. EPS file is often used when exchanging vector graphics (e.g. logos) that are only to be read but not edited by the receiver, such as sending the file to a print house.
An EPS is really a collection of several other image files all in one. EPS files are generated from several sources and are structured to published code constraints. An EPS file has two main parts:

• The Preview
• The high resolution image data

The preview of an EPS file is necessary to display the image in a page layout application, and the high-resolution portions of the file are necessary for imaging to a particular output device.
When you embed (Encapsulate) graphics in a document it is therefore called Encapsulated PostScript or EPS.

GIF

Gradually being replaced by the PNG format. GIF is preferred for images with large areas of solid colors, such as logos and text as graphics. GIF does not compress your pictures, which mean that they do not loose any image quality – but files are consequently large.

GIF files can either be in grayscale or RGB color spaces. Two main advantages with GIF over the JPG format:

• Can be used for animation: a pseudo animation can be created by using an animation feature found in flipbook style cartoons. This “flipping” of images can be used to create the illusion of true animation.
• Can have transparent backgrounds.

GIF files can only store and display 256 colors in the RGB or indexed color gamut. In addition, the GIF file can be “interlaced”, where as every other row of information can be displayed at one time. As soon as that initial row of information is received, the next rows of data are downloaded. These attributes make GIF files unsuitable for use in a print production workflow, but highly desirable in a Web design situation.

JPEG / JPG

Supported by photographs around the world for its good image quality and compression. JPEG is expected to become the international standard for encoding digitized photographs. JPEG’s greatest difference from all other file formats is that it uses Lossy compression. – thus you loose some image quality. Therefore always edit the original picture before saving it in the JPEG format. If you start with a JPEG file that needs edits, save it as an EPS or TIF file. This way, additional information will not get lost and the quality of the original JPEG image will be maintained.
The JPEG format supports 24-bits images or up to 16 million colors through the RGB, CMYK, and grayscale color spaces. The use of JPEG images is supported in HTML and Web applications. However, unlike a GIF file, all of the color information is stored in the file. There is no support for transparency in a JPEG file.

PDF

Portable Document Format (PDF) is an open file format which makes the PDF format suitable for sharing. These files can be viewed in a professional software program or a free acrobat reader.
New image file format with advantages over GIF and JPEG. PNG use lossless compression of data in a wonderful way – the format compress the images so that you will not be able to detect degradation of quality. PNG files are saved with .png extension. PNG file can support both 8-bit or 24-bit colors, using a lossless compression approach.

PNG

PNG file settings that can be controlled are:

• Transparency information
• File defined background color
• Adobe Gamma correction

Use of a PNG file in a Web project is a good fit. However, because of the lack of support for the CMYK color space, and the fact that there can be no color separations, the PNG file is not a good fit in a print production cycle.

TIFF

Optimal choice since the file format works on both MAC and PC platforms, supports almost any picture bit depth and allow for various form of compression. A TIFF file is the most widely used file format in desktop publishing today. It is a raster-based file that supports the following: RGB, CMYK, Grayscale, Lab, and Indexed color.

Note that this flexibility has a drawback: no current system can decode all TIFF file versions which simply mean that you need to test the TIFF file at your hand and see how it behaves.

TIFF files can be compressed by using an LZW lossless compression approach or JPEG lossy compression. For high-end print production, it is the best practice to use either LZW compression or a very small amount of JPEG compression. The JPEG compression approach is a lossy compression that will degrade image quality when used in large amounts.