WHAT IS AN IMAGE?

An image is an artifact that depicts visual perception, such as a photograph or other two-dimensional picture, that resembles a subject—usually a physical object—and thus provides a depiction of it. In the context of signal processing, an image is a distributed amplitude of color.

What is a computer image?

A computer image may refer to: Computer-generated imagery, still or moving imagery created by or with help of a computer. System image, a serialized (backup) copy of the entire state of a computer system.

What are the types of images?

Common Image File Formats

• TIFF (. tif, . tiff) …
• GIF (. gif) GIF or Graphics Interchange Format files are widely used for web graphics, because they are limited to only 256 colors, can allow for transparency, and can be animated. …
• PNG (. png) …
• EPS (. eps) …
• RAW Image Files (. raw, 

FEATURES OF AN IMAGE

What is local features of an image?

Local features refer to a pattern or distinct structure found in an image, such as a point, edge, or small image patch. They are usually associated with an image patch that differs from its immediate surroundings by texture, color, or intensity. … Examples of local features are blobs, corners, and edge pixels.

WHAT ARE BITMAP AND VECTOR IMAGES?

A bitmap (also called “raster”) graphic is created from rows of different colored pixels that together form an image. In their simplest form, bitmaps have only two colors, with each pixel being either black or white. With increasing complexity, an image can include more colors; photograph-quality images may have millions. Examples of bitmap graphic formats include GIF, JPEG, PNG, TIFF, XBM, BMP, and PCX as well as bitmap (i.e., screen) fonts. The image displayed on a computer monitor is also a bitmap, as are the outputs of printers, scanners, and similar devices. They are created using paint programs like Adobe Photoshop.

Vector (also known as “object-oriented”) graphics are constructed using mathematical formulas describing shapes, colors, and placement. Rather than a grid of pixels, a vector graphic consists of shapes, curves, lines, and text which together make a picture. While a bitmap image contains information about the color of each pixel, a vector graphic contains instructions about where to place each of the components. It is even possible to embed a bitmap graphic within a vector graphic, which is how vector-bitmap hybrid graphics work. It is not possible, however, to embed vector information within a bitmap. Examples of vector graphic formats are PICT, EPS, and WMF as well as PostScript and TrueType fonts. These are created with GIS and CAD applications as well as drawing programs like FreeHand.

SVG, or Scalable Vector Graphics, is a language for describing vector graphics in XML. With SVG, you can code graphics directly into an XML document. For more information about SVG,

bitmap and vector graphics both have their strengths and weaknesses:

• In general, a bitmap graphic is much larger than a similar vector graphic.
• Bitmap graphics are affected by resolution. If you enlarge a bitmap graphic, it will look jagged. When shrunk, its features become indistinct and fuzzy. This does not happen with vector graphics as their shapes are redrawn to compensate for changes in resolution.
• Altering vector graphics is easy because the shapes within them can be ungrouped and edited individually. However, vector graphics are difficult to modify or even display when they are not opened in programs that understand their rendering languages. For example, while many Mac OS drawing programs easily display and edit PICT files, few are able to do anything at all with WMF files. Most paint applications, however, are capable of opening many different kinds of bitmap graphic formats.
• You can easily convert one kind of bitmap file into another. You can also convert a vector graphic into a bitmap. However, it is very difficult to convert a bitmap graphic into a true vector graphic. It is even difficult to convert one kind of vector graphic into another (e.g., PICT to WMF).
• Vector graphics are not appropriate for complex images (e.g., digitized photographs).

A vector image is an image that results from a combination of points and lines with a mathematical formula, thus forming a polygon depicting a particular image object. The location of a vector image is called control points or nodes, where the location of each point has a definite position based on the x and y axis. In a vector image, each line or point can be added with various attributes, such as shape, line thickness, curves, line color, and fill color.

Vector Image Format

The format for Vector images itself varies, including:

• CDR (format from Corel Draw)
• AI (format from Adobe Illustration)
• SVG
• EPS
• PDF

FEATURES OF BITMAP IMAGES

What characteristics define a bitmap? Bitmap images are characterized by two parameters: the number of pixels (resolution) and the color depth per pixel. Color depth refers to the information contained within the image. For example, a 1-bit image means that a pixel could either be black or white.16 Sep 2016Color: Can depict very detailed images, since …Size: Take up more storage space and memory …Editable elements: Individual pixelsScalability: Not scalable. Pixelation occurs when

The characteristics of vector images are:

• Vector images are formed from a combination of individual objects consisting of points, lines and colors.
• Image size does not affect the quality of the displayed image, because it does not depend on image resolution.
• Has a relatively small size.

Pros of Vector Images

Vector images can have some advantages than other image format, such as:

• The storage space used by drawing objects is more efficient.
• Can be printed at high resolution using a printer.
• Images can be resized to any size without fear of deterioration.
• Vector images are easier to edit.

Disadvantages of Vector Graphics

But, this type of format can also have disadvantages. If the image is converted to a bitmap, it cannot generate the main vector anymore and loses all of its vector characteristics.

DIFFERENCES BETWEEN BITMAP AND VECTOR IMAGES

Bitmap (or raster) images are stored as a series of tiny dots called pixels. Each pixel is actually a very small square that is assigned a color, and then arranged in a pattern to form the image. When you zoom in on a bitmap image you can see the individual pixels that make up that image. Bitmap graphics can be edited by erasing or changing the color of individual pixels using a program such as Adobe Photoshop.

Unlike bitmaps, vector images are not based on pixel patterns, but instead use mathematical formulas to draw lines and curves that can be combined to create an image from geometric objects such as circles and polygons. Vector images are edited by manipulating the lines and curves that make up the image using a program such as Adobe Illustrator.

Vector images have some important advantages over bitmap images. Vector images tend to be smaller than bitmap images. That’s because a bitmap image has to store color information for each individual pixel that forms the image. A vector image just has to store the mathematical formulas that make up the image, which take up less space.

Vector images are also more scalable than bitmap images. When a bitmap image is scaled up you begin to see the individual pixels that make up the image. This is most noticeable in the edges of the image. There are ways of making these jagged edges less noticeable but this often results in making the image blurry as well. When a vector image is scaled up, the image is redrawn using the mathematical formula, so the resulting image is just as smooth as the original.

The three most popular image formats used on the Web (PNG, JPEG, and GIF) are bitmap formats. The Scalable Vector Graphics (SVG) format comes in a distant fourth due to a legacy of poor support for vector graphics in early browsers. Today however, all major browsers support the SVG (Scalable Vector Graphics) format.

Bitmap formats are best for images that need to have a wide range of color gradations, such as most photographs. Vector formats, on the other hand, are better for images that consist of a few areas of solid color. Examples of images that are well suited for the vector format include logos and type.

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