Vector and bitmap images are the two major graphic types. Both types are made up of many individual objects, and both respond differently when enlarged and/or reduced to produce different sizes of images. We can use both types of files, however we prefer vector files and we can change sizes easily without sacrificing quality using original vector formats. Vector images can be output at the highest quality in any scale because they are made of lines and panels rather than pixels or dots. Vector images are resolution independent. Common vector formats are eps, ai and pdf. These formats are available in most graphics programs.
A bitmap image (also called a raster image) is made of pixels (sometimes referred to as dots). The number of pixels in one square inch of an image is called the dpi (dots per inch) and is known as the resolution of the image (Example: 150 dpi means that the image has 150 dots per square inch within that image). Quite simply, the larger number of dots you have in your image produces a higher quality of reproduction. Bitmap images loose quality when the are re-sized from their original size and must be created with consideration for their output use. Bitmap images should be built at 150 dpi if they are built at the actual finished size. You can build the bitmap files at a smaller proportional size than the final usage size, but you must increase the resolution accordingly. For instance, if you build your file at a ratio of 1 inch = 1 foot, you should build the file at 300 dpi. In this case, you would build a 2 inch x 2 inch file at 300 dpi to print a resulting 2 foot x 2 foot image at 150 dpi. Common bitmap-based formats are jpeg, jpg, gif, tiff, png, pict and bmp. Although vector image is the preferred format for submitting artwork, it is not as common for non- designers and bitmap images at the correct resolution can be substituted.
Larger resolution files also use more bytes of memory & sometimes require special methods to transfer the images. Many graphic files become too large for standard email servers to upload so contact us if you need to get us a larger file.
