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Bitmap vs Vector

Raster / Bitmap vs Vector - Which is better?

Bitmap graphics are composed of pixels, each of which contains specific color information. A pixel is minutely small and a single image may be composed of hundreds of thousands of individual pixels. A graphic composed entirely of pixels each with its own color properties is ideal for photographic images where there are thousands, even millions of different colors. Complex fills, shading and gradient effects can easily be rendered. The Bitmap image offers as much freedom as an empty canvas. When a Bitmap graphic is saved, the computer is really saving an exact visual picture of the image: this pixel goes here and is this color, this pixel goes there and is that color, and so on and so on.

Rather than being composed of pixels, Vector graphics consist of points, lines, and curves which, when combined, can form complex objects. These objects can be filled with solid colors, gradients, and even patterns.
Vector graphics are mathematical creations. For this reason, the programs that are used to create them save instructions on how the image should be drawn, rather than how it looks. This is the key difference between the two types of graphics. Because the computer has a description of how the image should look, it can be redrawn at any size, in any position, without losing any quality. A vector graphic resized to 5 times its original dimensions is simply reproduced, exactly, at the new size. It can also be freely manipulated without losing coherence.

Because of these differences, there are instances when working with vector tools and formats is the best practice, and instances when working with raster tools and formats is the best practice and there are times when both formats come together.

So bitmaps have the upper hand when dealing with drop shadows or a full colour photograph but when we're talking solid spot colour objects and text, then vectors are far superior because of the following advantages:

1. Vectors are fully scalable without any loss of quality.

Vector art is key for printing. Since the art is made from a series of mathematical curves it will print very crisply even when resized. For instance, one can print a vector logo on a small sheet of copy paper, and then enlarge the same vector logo to billboard size and keep the same crisp quality. A low-resolution raster graphic would blur or pixelate excessively if it were enlarged from business card size to billboard size.

Bitmap vs Vector Illustration

2. Vectors can be easily customised using any vector editing software such as Corel Draw and Adobe Illustrator.

Vector graphics editors typically allow rotation, movement, mirroring, stretching, skewing, changing of layering order and combination of primitives into more complex objects. More sophisticated transformations include operations on closed shapes (combine, difference, intersection, etc.). Vector graphics are ideal for simple or composite drawings that need to be device-independent, or do not need to achieve photo-realism. For example, the PostScript and PDF page description languages use a vector graphics model.

3. Vectors are generally smaller files than bitmaps.

Computer displays are made up from grids of small rectangular cells called pixels. The picture is built up from these cells. The smaller and closer the cells are together, the better the quality of the image, but the bigger the file needed to store the data. If the number of pixels is kept constant, the size of each pixel will grow and the image becomes grainy (pixellated) when magnified, as the resolution of the eye enables it to pick out individual pixels.

Vector graphics files store the lines, shapes and colours that make up an image as mathematical formulae. A vector graphics program uses these mathematical formulae to construct the screen image, building the best quality image possible, given the screen resolution. The mathematical formulae determine where the dots that make up the image should be placed for the best results when displaying the image. Since these formulae can produce an image scalable to any size and detail, the quality of the image is only determined by the resolution of the display, and the file size of vector data generating the image stays the same. Printing the image to paper will usually give a sharper, higher resolution output than printing it to the screen but can use exactly the same vector data file.

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