Difference between Vector and Raster Graphics

Difference between Vector and Raster Graphics

Well, before we start to know about vector and raster graphics, we must understand a few basic terms of display graphics:

1: Pixel:

A pixel is the smallest element of a picture which represents on your screen. Pixel is actually a short form of “Picture Element”. Those are the small little dots that make the image to display on the computer, whether they are flat-screen (LCD) or tube (CRT) monitors.

The display screen is divided into a matrix of thousands or millions of pixels. You cannot see the individual pixel without zooming it, because they are so small. Most people prefer to look at smooth and clear images rather than pixelated one.

2: Bitmap (BMP): 

A bitmap is also an image file format. A bitmap is a type of file that displays small dots in a pattern that creates an overall image. The bitmap image is actually a grid made of rows and columns where specific cells with given value fill it in or leave it blank.

It is also called a bit-array or bitmap index. The more general term is pixmap which refers to a map of pixels, where each one may store more than two colors and you can use more than one bit per pixel. Sometimes the term bitmap implies one bit per pixel. While pixmap is used for images with multiple bits per pixel.

Raster Graphics

The Raster images use bitmaps to store information and display content. So, the large file needs a large bitmap and the larger image requires more disk space to store. For example, the image of 640 x 480 requires information to be stored for 307,200 pixels, while a 3072 x 2048 image needs to store information for a whopping 6,291,456 pixels.

We can use algorithms that compress images to reduce file sizes. Formats like jpeg and gif are commonly compressed. Scaling down these images could be easy but enlarging a bitmap makes it pixelated or blurred. Hence for images that need to scale it to different sizes, we should use vector graphics.

Its file extensions could be in:BMP, TIF, GIF, JPG.

Vector Graphics

The programs which place lines or shapes in a 2-D or 3-D environment sequentially are referred to as Vector Graphics. The Vector graphics are best for printing since it prints crisply even when they are enlarged. A vector is something that has a magnitude and direction. Its file is created and saved as a sequence of vector statements.

A bit in the file for each bit of line drawing we use commands which describe a series of points to be connected. So, as a result much smaller file is obtained.

Its file extensions could be in:SVG, EPS, PDF, AI, DXF.

From the above discussion, you have got an idea about vector and raster graphics. Now we will discuss the conversions of raster image and vector image briefly.

Their Conversions

Vector to Raster

Mostly the printers and display devices are raster devices. To display, we need to convert vector images to raster format. Then it would be a usable display or print. The required resolution is important in determining the size of the raster file generated.  The important point to note is that the size of the 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 the opposite path is harder because sometimes we need to edit the image while converting from raster to vector.

Raster to Vector:

The image tracing in computing could be referred to as vectorization and it’s simply about converting raster images to vector images. The vectorization could be used to retrieve the information that we have lost. Paint in Microsoft Windows can produce a bitmap output file so it would be easy to notice jagged lines. In this kind of 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.

Main Differences:

The main difference between vector and raster graphics is that:

  • Raster graphics are composed of pixels
  • Vector graphics are composed of paths

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