Two of the dominant programs in the graphic design industry are Adobe Photoshop and Adobe Illustrator. Both programs take very different approaches to designing images. Photoshop creates bitmaps, which are essentially small squares that blend together to create images. These images have a resolution that determines how many squares they have. The problem is that increasing the size of the image will reduce the image's resolution and lead to blurry and pixelated images.
Illustrator instead relies on vectors and lines, which are mathematical points. The program knows the ratio between each point and the size can be increased or reduced depending on the needs of the user without a loss in resolution. This makes vectors ideal for images that must sometimes be increased or decreased in size, such as company logos.
Photoshop and Illustrator are not completely different, since Photoshop has a pen tool that allows it to create vectors, though the user does not have as much control over the vectors as with Illustrator. When the user creates vectors, they must be rasterized and they then become a part of the bitmap.
The type of design used by Photoshop is known as a raster design. Photoshop makes it easier for graphic designers to make cosmetic changes to images since the user is not as bound to vectors. Therefore, images that are not the right saturation or that need significant repair work can be corrected more easily. Photoshop is especially good for making corrections to already existing images.
Both Programs are Useful for Commercial Printers
For various projects, from coupon booklets printing to catalog printing jobs, both Photoshop and Illustrator can be ideal programs to place in the hands of commercial printers. Many users will send their digital files in a Photoshop or Illustrator format and printing shops that want to expand their list of services will want to have trained graphic designers that understand both programs. However, a commercial print shop will then need to use Adobe InDesign to piece it all together and prepare it for the print run.