Vector Vs Bitmap Images Explained
February 25, 2017
What is the difference between vector and raster graphics? What type is better for layouts creation? What are the pros and cons of each type?
All graphical files contain information about images, no matter what format they are – jpg, gif, BMP, cdr, eps, ai, pdf, or any other. Each has unique properties and suits different tasks. However, among the vast number of graphic editors and formats, there are two global categories – vector and raster graphics.
Of course, professional designers do not need a reminder of how to use those types of images. But, beginners sometimes get confused and misunderstood. Let’s clarify the situation and answer some of the questions.
Bitmap Images (Raster Graphics)
Imagine a chessboard or a grid. Each of its squares is a raster point that has unique characteristics. Thus, a bitmap image is composed of points on the plane. The more such points have the image and the smaller they are – the better the quality of the image. Modern technologies allow to make high-quality photos and pictures with millions of points, so to see a single one, we need multiple zooming.
The characteristics of raster graphics are:
- The size of the image, expressed as the number of pixels in width and height (800 × 600px, 1024 × 768px, etc.), or as the total number of pixels (so the image size of 1600 × 1200px consists of 1.92 million pixels, which is about 2 megapixels);
- The number of colors used and color depth (these characteristics have the following relationship: N=2^k, where N is a number of colors, and k – color depth).
- The color model (RGB, CMYK, YCbCr, XYZ, etc.).
- Image resolution – the value that defines the number of dots (raster image elements) per unit area (or per unit length).
The most common bitmap graphics are photos, scanned images, exported vector images, screenshots. To know whether it’s expedient to use raster graphics in this or that case, you need to know its advantages and disadvantages.
- Allows you to create any image, regardless of its complexity. In contrast, vector graphics cannot accurately convey the effect of the transition from one color to another without a loss in the file’s size.
- Used almost everywhere, from small badges to posters.
- High processing speed: you’re managing quite fast with complex images if no scaling needed.
- Best suits popular input-output devices, such as monitors, digital cameras, scanners, matrix and inkjet printers, cell phones.
- Excessively large size of simple images.
- Impossibility of perfect scaling.
- The inability to print on a vector plotter.
Undoubtedly, bitmap images are much more popular. Still, the aforementioned disavantages might make you think about using an alternative in the form of vector graphics.
These images are not sets of points – rather, they are points with interconnecting vector lines. A vector image file contains information about the positions of the points, as well as about the line passing through the reference points. That is, any vector file contains information in the form of formulas and mathematical calculations. It has a comparatively small size, regardless of the actual size of the image. Vector graphics are indispensable when designing drawings, mapping, drawing schemes and so on.
- Data volume does not depend on the actual value of the object, which provides the possibility to use the minimum amount of information to describe arbitrarily large objects with files of minimum size.
- Because information about the object is stored in a narrative form, any particular element of the image could be scaled without quality loss (but if, for example, a curve is shown as a broken line, the scaling will reveal that it’s not actually a curve).
- The parameters of objects are stored and can be quickly changed. This also means that the moving, scaling, rotating, etc. does not degrade the picture quality. Moreover, generally, the dimensions are indicated in device-independent units, which leads to the best possible rasterization on raster devices.
- When increasing or decreasing an object, any of its line could be of a constant pre-specified width that is independent of the actual size of the depicted image.
- Not every graphics could be easily displayed in vector form: an original image may require a very large amount of complex descriptions that increases the volume of memory occupied.
- As a rule, the converting of a raster image into vector one is much more complicated than the reverse process. It’s called raster tracing, and it requires considerable computing power and processor time. In addition, it does not always provide the high quality of the resulting vector drawing.
- The advantage of vector images disappears if the vector format is displayed in raster resolution of extremely low resolution (e.g. 16×16).
So what’s better?
Answering this question we can ask another one: what’s better – a frying pan or a washing machine? Each graphic solves the specific range of tasks, so it’s all up to your purposes. Find your optimal solution by using the information presented in the article.