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What is the Difference Between Vector and Bitmap Images?

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  • Written By: David White
  • Edited By: Bronwyn Harris
  • Last Modified Date: 16 April 2014
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We see computer images all the time, but we rarely stop to think about the composition of those images. How are they put together? How are they manipulated? The vast majority of computer graphics fall into two categories: vector and bitmap. One is more complicated and time-consuming to create than the other, but both are in wide use.

The most elementary kind of image in any discussion of computer images is the bitmap image, which sounds like something from the early days of computing, a map of bits. A bitmap image is quite literally a collection of squares that, taken together, make up the image. The squares might be of different colors, but they are all the same size. Reduce any bitmap image to its parts and you'll see this in detail.

Because a bitmap image is this collection of squares, it doesn't hold up well to expansion. Designers, when talking about vector and bitmap images, often talk about the resolution of those images. That is how many dots per inch an image has. The more dots per inch, the better the resolution of the image. The higher the resolution, the better detail the image generally has; conversely, the lower the resolution, the less detail the image has.

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It can be difficult to resize bitmap images in some cases. When a bitmap images is reduced in size, some dots must be eliminated, lowering the resolution. When enlarged, a bitmap image can appear blocky if it does not have a high enough resolution to supply the information for the image's details.

The other half of the computer image equation is the vector image. This kind of image is much more sophisticated because it has more moving parts. Each vector image is made up of a handful of smaller images, just like the bitmap, except that the vector image's parts are scalable. This means that designers can change the resolution of a vector image in both directions, making a high-res image lower or making a low-res image higher. If designers are looking for an image that can be easily scaled in both directions, then their choice between vector and bitmap should be an easy one.

Something else to keep in mind in any discussion of computer images is that the vector images are not restricted to a rectangular shape, as are the bitmap images. A designer who places a vector image on top of another image won't cover up any of the detail of the image underneath. A bitmap image does this because it is entirely made up of square pixels, even the white ones in the background that we don't realize are there. This is another point to keep in mind when choosing between vector and bitmap.

A key point in the discussion of vector and bitmap, however, is that most widely used graphics file formats are of the bitmap variety, like GIFs, JPGs, PICTs, and TIFFs. This is because vector images lack the consistency of bitmap images in terms of photo-realism. If you're trying to decide between image types for digital photos or photo-like images on a web page, the better choice for a more photo-realistic image is the bitmap. Many vector images and are commonly converted to bitmap format for use on web pages. The widely known exception to this is the PDF file, which is a vector image and looks rather good when unconverted.

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Discuss this Article

anon74299
Post 17

I wish this discussion (article and comments thread) was dated! Useful info though very preliminary.

anon52785
Post 16

just try to compare them yourself. I think it's better that way anyway for me. it stops me copying and pasting!

anon52636
Post 15

i really think that this site features some great information about the differences between bitmap and vector but i think that it should've mentioned about what it can be used for.

by the way i think both - anon4994 and anon9953 also milagros are right on their thinking. i would say everyone has right to say what they want to say.

anon18750
Post 9

I like this site as it is helping me get a good grade. thanks Derby Lass

anon18484
Post 6

1. Vectors are more flexible because they can be resized from high res to low res _and_ vice versa without losing quality.

2. Bitmaps have to be a rectangle, but vectors don't -- vector images can contain curved lines or shapes like polygons.

3. Vectors contain individual objects whereas bitmaps contain pixels.

anon14936
Post 5

this helped with my college work, so thanks !

milagros
Post 3

To Anon4994 and Anon9953 - I respectfully disagree with your opinions. The article lists at least these three differences:

1. Vectors are more flexible because they can be resized from high res to low res _and_ vice versa without losing quality.

2. Bitmaps have to be a rectangle, but vectors don't -- vector images can contain curved lines or shapes like polygons.

3. Vectors contain individual objects whereas bitmaps contain pixels.

anon9953
Post 2

I agree with the last comment, this isn't helpful. There is nothing about the differences here!

anon4994
Post 1

i don't think this is very helpful because it doesn't say the difference between bitmap images and vector images.

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