Promotional Products Companies normally require EPS Vector files to produce quality merchandise. Vector files specifically allow for the EPS file to be enlarged and shrunken to any size.
Other important art file terms to understand.
RGB vs. CMYK
RGB (red, green, blue) are ‘additive colours’. If we combine red, green and blue light we get white. This is the principle behind computer monitors.
CMYK (cyan, magenta, yellow, black) is the opposite being ‘subtractive colours’. If we combine CMYK on paper we perceive black, this is because the colours absorb the light shining onto the page. Black is represented as ‘k’ to avoid confusion as ‘b’ is already used in RGB to represent blue.
All RGB artwork files must be converted to CMYK before film output as they will separate differently and will either have a subtle or dramatic colour difference when printed.
EPS (Encapsulated PostScript)
EPS is a standard file format for importing and exporting postscript files, which carry information from the computer to printers and image setters.
An EPS file can contain any combination of text, graphics and images. Since it is actually a postscript file, it is the most versatile file format that is available.
EPS files can be created through Illustrator, Acrobat and Photoshop. It can also be used as an export feature through Quark and Indesign.
When created in Illustrator the EPS file is a vector image. A vector image basically means it is not made up of pixels, so it can be scaled up or down without losing any quality.
When created in Photoshop the EPS file is a raster image, which contains pixels. This means that when the file is scaled up or down the quality will be restricted and in some cases become pixilated.
EPS files made through acrobat, or exported through quark and indesign can contain both vector and raster files so scaling may also be restricted.
BMP (Bitmap)
A BMP file is an image file widely used in Windows based PCs.
As the bitmap files can only be saved as RGB, so not ideal for prepress or formatting applications that prefer CMYK. Bitmap files are also un-editable files, so corrections or alterations are complicated and can cause problems when reproducing.
BMP’s can be created using Photoshop and standard windows programs such as paint. They can be opened in Illustrator and placed into Quark and Indesign.
JPG / JPEG (Joint Photographic Experts Group)
A JPEG is a compressed raster image file. JPEG images are not limited to a certain amount of colour, like GIF images are.
Therefore, the JPEG format is best for compressing photographic images; this is why the majority of images you would find on the web are JPEG files.
However, JPEG uses a lossless compression, which means some quality is lost when the image is compressed. If the image is compressed too much, the graphics become noticeably pixelated.
As JPEG files are predominantly RGB many issues arise when sent to an image setter for film output. The compression and colour-space of the files usually affects the output and colour matching in the print is inaccurate or sometimes non-existent as they sometimes default to greyscale.
JPEGs can be created using Photoshop and Illustrator and can be exported through Indesign & Acrobat. They cannot be used with Quark.
GIF (Graphics Interchange Format)
GIF files are compressed raster image files. Similar to the JPEG, GIF files use a lossless compression. The files are also saved at 72dpi for screen viewing, where 300dpi is the standard minimum for quality output.
GIF is a file that shouldn't be used for pre-press, it is far more suited for web design. Unfortunately, GIF images keep popping up in art files made by amateur designers who use Word, Powerpoint or even Excel to create artwork.
Photoshop and standard Windows applications such as Paint are used to create GIF files. They cannot be used with Quark.
TIF/TIFF (Tagged Image File Format)
TIFF is the leading commercial and professional image standard. TIF files are raster files that can be saved as either RGB or CMYK and can be placed into almost any application. Although they aren’t the most economical files, if they are created properly (300dpi & CMYK) the print reproduction will be at its best. TIF files can be created using Photoshop.
Source - APPA Return to the News Archive