Raster Vector Graphics

[Recaredo Latreche]

PixelIn Computer graphics, a pixel, dot, or picture element is a physical point in a picture. A pixel is simply the smallest addressable element of a picture represented on a screen. A majority of pictures that we see on our computer screen are raster images. The selfie that you click with your mobile phone is another example of a raster image. An image is made up using a collection of pixels referred to as a bitmap.

Bitmap: In computer graphics, a bitmap is a mapping from some domain (for example, a range of integers) to bits, that is, values which are zero or one. It is also called a bit array or bitmap index. The more general term pixmap refers to a map of pixels, where each one may store more than two colors, thus using more than one bit per pixel. Often bitmap is used for this as well. In some contexts, the term bitmap implies one bit per pixel, while pixmap is used for images with multiple bits per pixel.

Raster images use bit maps to store information. This means a large file needs a large bitmap. The larger the image, the more disk space the image file will take up. As an example, a 640 x 480 image requires information to be stored for 307,200 pixels, while a 3072 x 2048 image (from a 6.3 Megapixel digital camera) needs to store information for a whopping 6,291,456 pixels. We use algorithms that compress images to help reduce these file sizes. Image formats like jpeg and gif are common compressed image formats. Scaling down these images is easy but enlarging a bitmap makes it pixelated or simply blurred. Hence for images that need to scale to different sizes, we use vector graphics.

Making use of sequential commands or mathematical statements or programs which place lines or shapes in a 2-D or 3-D environment is referred to as Vector Graphics. Vector graphics are best for printing since it is composed of a series of mathematical curves. As a result vector graphics print crisply even when they are enlarged. In physics: A vector is something that has a magnitude and direction. In vector graphics, the file is created and saved as a sequence of vector statements. Rather than having a bit in the file for each bit of line drawing, we use commands which describe a series of points to be connected. As a result, a much smaller file is obtained.

As a visual communicator, it is your job to put together the best, most professional products to deliver the right message to the right audience. Understanding different file formats and mediums is essential to help you communicate effectively. Raster images and vector graphics have different purposes in design, and it is essential for you to understand when and where to use them for the right purpose.

Vector graphics are also known as scalable vector graphics (SVG). These graphics consist of anchored dots and are connected by lines and curves, similar to the connect-the-dot activities you may have done as a kid. Because these graphics are not based on pixels, they are known as resolution independent, which makes them infinitely scalable. Their lines are sharp, without any loss in quality or detail, no matter what their size. These graphics are also device-independent, which means their quality doesn't depend on the number of dots available on a printer or the number of pixels on a screen. Because they consist of lines and anchor points, the size of the file is relatively small.

Raster images are made of pixels or tiny dots that use color and tone to produce the image. Pixels appear like little squares on graph paper when the image is zoomed in or enlarged. These images are created by digital cameras, by scanning images into a computer or with raster-based software. Each image can only contain a fixed number of pixels; the amount of pixels determines the quality of the image. This is known as resolution. More pixels result in better quality at the same or larger sizes as the original, but this also increases the size of the file and the amount of space it takes to store the file. The lower the number of pixels, the lower the resolution. Resolution limits the size the image can be scaled up without being able to see pixels. However, a high resolution image printed at a small size will cause the pixels to "cram" together and will make the image look as unprofessional as not having enough pixels in a large image.

A vector graphic's small file size and scalability make it uniquely suitable for use in digital printing from business cards to billboards. They're also used in lower thirds for videos, web-based objects and rendering 2D or 3D computer animation. Their native files are needed for coin designs, laser engraving, t-shirts, patches, etc. Raster images are best for digital photos and print materials. If your project requires scalable shapes and solid colors, vector is the best choice, but if your project requires complex color blends, raster is the preferred format.

i just read an article about raster and vector graphics. Well this suddenly popped in my mind. i read that in vector graphics its basically specifying equations/paths for objects or shapes and not as pixels.

they have infinite resolution - no matter how large you expand or how small you contract the image, the math creating it holds up and it will always show smooth, clear edges and details. The little 36KB logo file mentioned above can be printed at ANY size

To give u an example lets say i have a rectangle defined in a raster image (for e.g. a bitmap so to speak) having width 100 and height 100. No matter what color i use to fill the rectangle, it would need 100x100 (width*height) pixels to represent it. In case of vector(for e.g. an eps image), you will just store the two coordinates the left,top and right,bottom. The amount of pixels needed is totally dependent on the output device and the scale to which you want to evaluate the rectangle on the output device.

Another subtle difference pops up when u perform zooming in. In the raster image for zooming in, u would still use the same 100x100 pixels and replicate the rows and cols of pixels based on how much magnification is needed and this gives u the characteristic blockiness of a raster image. However, for a vector, u can reevaluate the color at a new interval based on the fill attribute assigned to the rectangle thus u donot get the blockiness and get a much higher visual quality. I hope this clears up the difference.

Raster and vectors are popular terms in graphic designing. But what are these? Raster images are made up of many tiny pixels, whereas vector images have formed using mathematical paths. So, what is the difference, and why is knowing the difference important? Let's discuss raster vs vector images in detail!

A raster image is a common term used in the field of computers and digital photography. A raster is sometimes also known as a bitmap image. It is represented in the form of a rectangular grid of pixels which are viewable using a bitmapped display. In raster-based imaging, it is easy to make smaller images. However, when it comes to increasing or decreasing the size and resolution, it is a bit challenging.

A vector image or graphic is defined and created on a plane by connecting lines and curves. It uses mathematical equations to form shapes. It creates a finer and more detailed image. You can see clear lines, points, and curve when you zoom in on the image. Vector graphics are used by all types of artists, design experts, and creative professionals. It makes creating illustrations, logos, and other types of designs for printing on big objects easy. You would have heard or observed many graphic designers talking about converting the images to vectors before printing.

Raster graphics are made up of orderly arranged colored pixels to display any image whereas, vector graphics are composed of paths using a mathematical formula that is a vector that directs the route and shape.

Common vector file types are .ai, .eps, .pdf, svg, sketch and the editors used are often - Adobe Illustrator or Sketch. Images that need to be scaled to different sizes, vector graphics are used to achieve those results.

With vector images, you can increase the size of the image to the desirable extent and, there will be no compromise on the quality. Users can increase the sizes to any limit as long as their computer supports that. It is the fundamental difference that makes vector images a clean winner over raster images. But having said that, there are reasons where using raster images may be the better solution.

One such example photographs. Pictures are always raster images. You can convert the image to a vector, but it may be a complex one, and the end result will witness a drop in finer details. Therefore for photographs, raster images are best suited.

Other examples include postcards printing that have an illustrated background (vector) and the highest resolution possible. Booklet printing features valuables product information (vector) with the product images (raster) you can adjust, reshape it whichever way you want. So we can conclude there are different purposes for using both raster and vector images.

If your project requires you to work with complex colors, themes, and blends, like in painting and all kinds of artwork, raster should be the preferred format. But if your project requires you to work on solid colors and scalable shapes like drawing, vector imaging is the solution.

Raster (or bitmap) images are generally what you think about when thinking of images. These are the types of images that are produced when scanning or photographing an object. Raster images are compiled using pixels, or tiny dots, containing unique color and tonal information that come together to create the image.

Since raster images are pixel based, they are resolution dependent. The number of pixels that make up an image as well as how many of those pixels are displayed per inch, both determine the quality of an image. As you may have guessed, the more pixels in the image and the higher the resolution is, the higher quality the image will be.

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