Updated: Jan 27, 2022
What’s the difference between raster and vector? It’s a common question asked by newbie designers, webmasters, marketers, and others who create and print artwork. It’s time to clarify the difference between raster and vector images.
In this guide to raster and vector images, you’ll learn:
What is a raster image?
What is a vector image?
How are raster and vector images different?
When should you use raster or vector?
Keep reading to become an expert on raster and vector images!
Before we begin with what vector graphics and raster graphics are, we must understand a few basic terms:
In Computer graphics a pixel, dots, or picture element is a physical point in a picture. A pixel is simply the smallest addressable element of a picture represented on a screen.
A majority of pictures that we see on our computer screen are raster images. The selfie that you click with your mobile phone is another example of a raster image. An image is made up using a collection of pixels referred to as a bitmap.
In computer graphics, a bitmap is a mapping from some domain (for example, a range of integers) to bits, that is, values which are zero or one. It is also called a bit array or bitmap index. The more general term pixmap refers to a map of pixels, where each one may store more than two colors, thus using more than one bit per pixel. Often bitmap is used for this as well. In some contexts, the term bitmap implies one bit per pixel, while pixmap is used for images with multiple bits per pixel.
There are two main type of image files: Raster and Vector. Raster images are created with pixel-based software or captured with a camera or scanner. They are more common in general such as jpg, gif, png, and are widely used on the web. Vector graphics are math-defined shapes created with vector software and are not as common; used in CAD/engineering, 3D animation, and Graphic Design for processes that reproduce an image onto an object such as engraving, etching, cut stencils. Knowing what visual file type to use, and what the difference is, is an integral part of experience design.
When using a raster program you paint an image and it's similar to dipping a brush in paint and painting. You can blend colors to soften the transition from one color to another.
When using a vector program you draw the outline of shapes: and it's similar to creating an image with tiles of all different shapes and sizes. e.g. an eye shape, a nose shape, a lip shape. These shapes called objects display one single color each.
WHAT IS A RASTER IMAGE?
Raster images, also known as bitmaps, are comprised of individual pixels of color. Each color pixel contributes to the overall image. Raster images might be compared to pointillist paintings, which are composed with a series of individually-colored dots of paint. When zoomed in closely, the individual pixels can be observed. Each paint dot in a pointillist painting might represent a single pixel in a raster image. When viewed as an individual dot, it’s just a color; but when viewed as a whole, the colored dots make up a vivid and detailed painting. The pixels in a raster image work in the same manner, which provides for rich details and pixel-by-pixel editing.
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The resolution of a raster file is referred to as DPI (dots per inch) or PPI (points per inch) and is the main determining factor for increasing file size. Essentially all digital photography is raster-based. Most graphic files found online are also raster-based and saved for a screen resolution of 72 DPI, a larger file size is usually required for use in printed material where the standard resolution is 300 DPI.
Raster images are ideal for photo editing and creating digital paintings in programs such as Photoshop and GIMP , and they can be compressed for storage and web optimized images. File extensions: .BMP, .TIF, .GIF, .JPG
WHAT IS A VECTOR IMAGE?
A vector image or graphic is defined and created on a plane by connecting lines and curves. It uses mathematical equations to form shapes. It creates a finer and more detailed image. You can see clear lines, points, and curve when you zoom in on the image. Vector graphics are used by all types of artists, design experts, and creative professionals. It makes creating illustrations, logos, and other types of designs for printing on big objects easy. You would have heard or observed many graphic designers talking about converting the images to vectors before printing. Since mathematical formulas dictate how the image is rendered, vector images retain their appearance regardless of size. They can be scaled infinitely. Vector images can be created and edited in programs such as Illustrator, CorelDraw, and InkScape (don’t worry, these visual editors do the math for you).
Vectors can be used to imitate photographs, they’re best-suited for designs that use simple, solid colors. Vector images are comprised of shapes, and each shape has its own color; thus, vectors cannot achieve the color gradients, shadows, and shading that raster images can (it is possible to mimic them, but it requires rasterizing part of the image – which means it would not be a true vector). True vector graphics are comprised of line art, sometimes called wireframes, that are filled with color.
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Because vectors can be infinitely scaled without loss of quality, they’re excellent for logos, illustrations, engravings, etchings, product artwork, signage, and embroidery. Vectors should not be used for digital paintings or photo editing; however, they’re perfect for projects such as printing stickers that do not include photos. Vector graphics are best for printing since it is composed of a series of mathematical curves. As a result vector graphics print crisply even when they are enlarged. In physics: A vector is something which has a magnitude and direction. In vector graphics, the file is created and saved as a sequence of vector statements. Rather than having a bit in the file for each bit of line drawing we use commands which describe series of points to be connected.
File extensions : .SVG, .EPS, .PDF, .AI, .DXF
NOTE: It’s important to note that, with the exception of the SVG format, vectors must be rasterized before they can be used on the web.
HOW ARE RASTER AND VECTOR IMAGES DIFFERENT?
The main difference between vector and raster graphics is that raster graphics are composed of pixels, while vector graphics are composed of paths. A raster graphic, such as a gif or jpeg, is an array of pixels of various colors, which together form an image.
Comprised of pixels, arranged to form an image
Comprised of pixels, arranged to form an image
Capable of rich, complex color blends
Large file sizes (but can be compressed)
File types include .jpg, .gif, .png, .tif, .bmp, .psd; plus .eps and .pdf when created by raster programs
Raster software includes Photoshop and GIMP
Perfect for “painting”
Capable of detailed editing
Comprised of paths, dictated by mathematical formulas
Difficult to blend colors without rasterizing
Small file sizes
File types include .ai, .cdr, .svg; plus .eps and .pdf when created by vector programs
Vector software includes Illustrator, CorelDraw, and InkScape
Perfect for “drawing”
Less detailed, but offers precise paths
WHEN SHOULD YOU USE RASTER OR VECTOR?
Raster images are best for photos, while vectors are best for logos, illustrations, engravings, etchings, product artwork, signage, and embroidery. Some liken raster images to paintings and vectors to drawing; if your project requires complex color blends, such as in painting, raster is the preferred format; if your project requires scalable shapes and solid colors, such as in drawing, vector is the best choice.
Many projects combine raster and vector images together: a brochure, for example, might include a corporate logo (vector) and a photo of happy customers (raster) – often coupled in layout software such as InDesign or QuarkXpress (though Illustrator and Photoshop can also be used to pair raster and vector images). Other examples include printing postcards that feature an illustrated background (vector) with a foreground photo (raster), online catalog printing that features scalable product information tables vector) alongside product images (raster), and business greeting card printing that combines corporate logos (vectors) with photos (rasters).
Ultimately, it boils down to what you’re creating and its intended use. If you need a brand logo that will be used time and again in multiple media – print, digital, television, product etching, signage, etc. – you should create a vector that can be scaled as-needed, then output in whichever format you need at any given time. If you want to edit a photo or make a sweet digital painting, you should create a raster that’s capable of rendering complex color blends and mimicking the natural qualities of light.
Typically you can distinguish between raster and vector formats by looking closely at the edges of graphic elements like text and logos. File extensions will also suggest which category a file will fall under, though there are always exceptions to the rule.
Bitmap Image File
Joint Photographic Experts Group (JPEG)
Portable Network Graphics (PNG)
Graphics Interchange Format (GIF)
Tagged Image File Format (TIFF)
Adobe Photoshop File
Corel Paint File
Encapsulated PostScript File (EPS)
Scalable Vector Graphics (SVG)
Adobe Illustrator File
Corel Draw File
Portable Document Format (PDF)
Note: Any of the above file types can be exported to a pdf format, so these files can be
either vector or raster or a combination of the two.
Vector to Raster:
Printers and display devices are raster devices. As a result we need to convert vector images to raster format before they can be used i.e. displayed or printed. The required resolution plays an vital role in determining the size of raster file generated. Here it is important to note that the size of vector image to be converted always remains the same. It is convenient to convert a vector file to a range of bitmap/raster file formats but going down opposite path is harder.( because at times we need to edit the image while converting from raster to vector)
Raster to Vector:
Image tracing in computing can be referred to vectorization and it’s simply the conversion of raster images to vector images. An interesting application of vectorization is to update images and recover work. Vectorization can be used to retrieve information that we have lost. Paint in Microsoft Windows produces a bitmap output file. It is easy to notice jagged lines in Paint. In this kind of a conversion the image size reduces drastically. As a result an exact conversion is not possible in this scenario. Due to various approximations and editing that is done in the process of conversion the converted images are not of good quality.