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What are the differences between vector and bitmap files?

In my twelve years in the design industry this is easily the one question I get asked by customers more than any other. Therefore I would like to write an explanation of the differences between the two file types, the advantages/disadvantages in choosing one over the other and to try and clear up any confusion once and for all!

So how do they differ?

Bitmap artwork is created using individual pixels; the total number of pixels is determined by the physical size and resolution of the artwork, which is often abbreviated as dpi, or DPI (Dots Per Inch). To give an example a 10cm x 10cm image at 72dpi will contain 80,089 pixels, whereas a 10cm x 10cm image at 300dpi will contain 1,390,041 pixels.

Without getting overly technical vector artwork uses geometrical primitives such as points, lines, curves and shapes or polygons, which are all based on mathematical expressions, to create the final image as opposed to individual pixels.

When viewed side-by-side there can often be very little to choose between vector and bitmap files, it’s only when you take a closer look that the difference is obvious, as illustrated by the two sets of Twitter logos below.

Vector And Bitmap Comparison

A comparison between vector and bitmap artwork

Is dpi important when creating artwork?

Yes, very. The dpi of artwork will change depending on how it is to be used. Typically computer monitors, laptops, tablets and mobile devices all have a screen resolution of 72dpi, whereas traditional 4-colour and digital printing requires artwork to be supplied at 300dpi.

Advantages and disadvantages of both formats

Whilst there is no right and wrong way of creating artwork, both file formats have their advantages and disadvantages. I’ve listed below those which I feel will be the biggest help to you.

Vector files

+ Vector files can be resized almost indefinitely; therefore they are the ideal choice for creating graphics that will be used across multiple applications at differing sizes, a company logo for example.

+ Vector files can be converted to bitmapped images quickly and easily.

– Very complex vector files contain large amounts of information, which can cause your computer to slow down considerably or even crash.

– Vector artwork can take a lot of skill, time and therefore cost to create, making it unsuitable for smaller budgets or time critical projects.

Bitmap files

+ Compared to vectors bitmap files are a lot easier, quicker and therefore cheaper to create. If you have a digital camera or a desktop scanner you can create bitmap artwork in a matter of minutes.

+ Bitmap artwork can be saved in a wide range of file formats including TIFFs, JPEGs, GIFs and PNGs, making them suitable for printed, electronic and online media.

– The biggest disadvantage of bitmaps is their lack of upward scalability. Once bitmap artwork is enlarged beyond its original size there is a huge loss in image quality.

– Bitmap files are very storage hungry compared to vectors, especially when saved for print. An A3 vector file could be less than 1MB in size, whereas the same artwork saved as a bitmap could be upwards of 50MB!

So there you have it, I hope you found this article useful and the information above helps you understand the advantages and disadvantages of both vector and bitmap files when creating your artwork. If you have any comments or questions on this blog post, or have requests for future articles please use the form below or email, as always your feedback will be gratefully received.