File Types - Artwork Files and Image Requirements
We accept Eps and PDF files containing either high resolution (300 dpi) bitmap images, for printing digitally, or vector images for other printing methods; screen printing (for example).
(Please note: with all artwork, fonts need to be converted to outlines to avoid design alterations when we open the files).
Suitable for litho and digital printing Bitmap images (also known as raster images) are made up of pixels in a grid. Pixels are picture elements; tiny dots of individual color that make up what you see on your screen. All these tiny dots of color come together to form the images. Bitmap images are resolution dependent. Resolution refers to the number of pixels in an image and is stated as dpi (dots per inch). Bitmap images are displayed on your computer screen at screen resolution 72 dpi. However, when printing bitmaps, a printer needs much more image data than a monitor. In order to render a bitmap image accurately, printers need a minimum of 300 dpi. Because bitmaps are resolution dependent, it's difficult to increase or decrease their size without sacrificing a degree of image quality. When you reduce the size of a bitmap image you must throw away pixels. When you increase the size of a bitmap image the software has to create new pixels. When creating pixels, software must estimate the color values of the new pixels based on the surrounding pixels. This process is called interpolation. Scaling a bitmap image to a smaller size doesn't have any effect; in fact, when you do this you are effectively increasing the dpi of the image so that it will print clearer.
Common bitmap formats include:
- JPEG, JPG
- PICT (Macintosh)
- PSD (Adobe Photoshop)
The bitmap editing program we use is Adobe Photoshop.
Suitable for all types of printing Vector images are made up of many individual, scalable objects. These objects are defined by mathematical equations rather than pixels, so they always render at the highest quality. Objects may consist of lines, curves, and shapes with editable attributes such as colour, fill, and outline. Because they're scalable, vector-based images are resolution independent. You can increase and decrease the size of vector images to any degree and your lines will remain crisp and sharp, both on screen and in print. Fonts are a type of vector object (unless in a bitmap). Vector images have many advantages, but the primary disadvantage is that they're unsuitable for producing photo-realistic imagery. Vector images are usually made up of solid areas of color or gradients, but they cannot depict the continuous subtle tones of a photograph. Vector images primarily originate from software. You can't scan an image and save it as a vector file without using special conversion software. On the other hand, vector images can, quite easily, be converted to bitmaps. This process is called rasterizing.
Common vector formats include:
- AI (Adobe Illustrator)
- CDR (CorelDRAW)
- CMX (Corel Exchange)
- CGM Computer Graphics Metafile
- DXF AutoCAD
- WMF Windows Metafile
The vector editing program we use is Adobe Illustrator.
Eps and PDF Files
Depends what they contain as to printing capabitlies
Eps and PDF files are types of PostScript files. This means that they are designed first and foremost as files to preview artwork and not to print from. PostScript files consist of functions for describing and positioning lines, shapes, fills, and other graphical elements, which in essence means that they can contain both Bitmap and Vector based images. This means that it depends on what the file contains as to its suitability to printing, which we find out by opening the file in Adobe Illustrator. Because of the nature of PostScript files they can be ready in a variety of programs.