Digital image


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Digital image

  1. 1. DIGITAL IMAGE Presentation By: Saurabh Mishra
  2. 2. DIGITAL IMAGE A digital image is a numeric (binary) representation of a two dimensional image. Digital images are of two types • Raster Image • Vector Image Digital image usually refer to raster or bitmapped images.
  3. 3. RASTER IMAGE A Raster graphics image is a dot matrix data structure representing a rectangular grid of pixels or points of colour. The smiley face in the bottom left corner is a bitmap image. When enlarged, individual pixels appear as squares. Zooming in further, they can be analyzed, with their colors constructed by adding the values for red, green and blue.
  4. 4. PIXELS In raster image pixel is the smallest addressable element which have its own characteristic. In a digital image each pixel has its own color value generally in rgb format.
  5. 5. COLOUR DEPTH Colour depth (bit depth) is the number of bits used to indicate colour of a single pixel in a digital image. COLOUR DEPTH NUMBER OF COLOURS 1 bit 2 monochrome 2 bit 4 grayscale 4 bit 16 8 bit 256 VGA 24 bit 16777216 or 16M True Color 32 bit 4294967296 Deep Color
  6. 6. Color Depth:1 bit Size:7.54 KB Color Depth:2 bit Size:15.1 KB Color Depth:8 bit Size:60.45 KB Color Depth:4 bit Size: 30.2 KB Color Depth:24 bit Size:181 KB
  7. 7. RASTER IMAGE SIZE The bits representing the bitmap pixels may be packed or unpacked (spaced out to byte or word boundaries), depending on the format or device requirements. Depending on the color depth, a pixel in the picture will occupy at least n/8 bytes, where n is the bit depth. Size of image (in Bytes)=width*height*n/8
  8. 8. VECTOR IMAGE Vector graphics is the use of geometrical primitives such as points, lines, curves, and shapes or polygon(s), which are all based on mathematical expressions, to represent images in computer graphics
  9. 9. TYPICAL PRIMITIVE OBJECTS Any particular vector file format supports only some kinds of primitive objects. Nearly all vector file formats support simple and fast-rendering primitive objects: • • • • Lines, polylines and polygons Bézier curves and bezigons Circles and ellipses Text
  10. 10. PRINTING Vector art is ideal for printing. Since the art is made from a series of mathematical curves, it will print very crisply even when resized. For instance, one can print a vector logo on a small sheet of copy paper, and then enlarge the same vector logo to billboard size and keep the same crisp quality.
  11. 11. Standards The World Wide Web Consortium (W3C) standard for vector graphics is Scalable Vector Graphics (SVG). The standard is complex and has been relatively slow to be established at least in part owing to commercial interests. Many web browsers now have some support for rendering SVG data.
  12. 12. Vector images could be magnified to any amount, it never breaks into small pixels.
  13. 13. References • Wikipedia • Google Images
  14. 14. Thank You!