Raster and vector images are two forms of representing the images.
Raster (Bitmap) Images
Raster images are made up of a set grid of dots called pixels where each pixel is assigned a color value. Unlike a vector image, raster images are resolution dependent. When you change the size of a raster image, you shrink or stretch the pixels themselves which can result in a significant loss of clarity and very blurry image. Raster editors such as Photoshop or GIMP are great for photographs as well as for adding effects, shadows and textures to designs.
• Is bound by the number of pixels in the image. It cannot be scaled up without losing quality.
• Large (dimension) & detailed images equal large file size
• Some service providers like engravers, stencil-cut signs, etc, must have vector art.
• It is more difficult to print raster images using a limited amount of spot colors
• Conversion to vector may be time consuming because of the complexity of function.
Vector images are made up of basic geometric shapes such as points, lines and curves. Logo designs and print work such as brochures and posters should be designed as vector images using vector drawing software like Adobe Illustrator, Corel Draw or Inkscape.
• Made of mathematical calculations that form objects and lines
• Can be scaled to any size without losing quality
• Resolution-independent: Can be printed at any resolution
• Number of colors can be easily increased or reduced to adjust printing budget.
• A large dimension vector graphic can maintain a small file size.
• Vector art is required by many service providers
• Can be easily converted to raster.
• It is not the best format for photographs or photo-like elements with blends of color