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Understanding Computer Graphics: Bitmap vs. Vector, Formats & Color Schemes

Explore how computers handle graphic objects, learn differences between bitmap and vector files, various graphic file formats, and color representation methods. Understand pixel bitmap graphics and advantages of using vector graphics. Discover common graphic file formats like Bitmap (BMP), Gif, and Jpeg. Dive into color depth, RGB color scheme, and CMYK color scheme for printing.

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Understanding Computer Graphics: Bitmap vs. Vector, Formats & Color Schemes

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  1. In this chapter, you will learn How computer handles graphic objects The differences between a bitmap file and a vector file The differences among different common graphic file formats By Netbalone - www.netbalone.com

  2. Handling Computer Graphics • Computer Handles data in binary format: 0 or 1 (bit) 28 = 256 216 = 65,535 224 = 16,777,216 232 = 4,294,967,296 By Netbalone - www.netbalone.com

  3. Pixel Bitmap Graphics • A bitmap graphic is represented by a dot pattern • Each dot is called a Pixel (picture element) • A pixel has a single color only By Netbalone - www.netbalone.com

  4. To have a better understanding of bitmap graphics, let’s start with the simplest type of bitmap picture - Monochrome (i.e. B&W) Bitmap By Netbalone - www.netbalone.com

  5. B&W Bitmap Graphics • A pixel can be Black or white (2 states) • So, 1 bit can be used to code the color 1111111111111 1111111111111 0001111111111 1011111111111 1100011111111 1111000111111 1111110111111 1111111000011 1111111111001 1111111111110 1111111111110 1111111111111 1 - White 0 - Black By Netbalone - www.netbalone.com

  6. B&W Bitmap Graphics • Therefore, a full screen (800 x 600) monochrome bitmap picture requires storage of (800 x 600 x 1) bits = 480000 bits = 60000 bytes = 58.59 kB By Netbalone - www.netbalone.com

  7. 110 111 100 101 010 011 001 000 Grayscale Bitmap Graphics • Grayscale graphics are created by using shades of gray • 8 levels of grayscale How many bits should be used to represent the gray colors of each pixel? 3 bits By Netbalone - www.netbalone.com

  8. 256 colors Bitmap Graphics How many bits are necessary to represent 256 colors in each pixel? 8 bits By Netbalone - www.netbalone.com

  9. Question: • How many bits are necessary to represent a 800 x 600 graphic of 256 colors? Number of bits used = 800 x 600 x 8 bits = 3,840,000 bits (Storage required: 468.75 kB) The larger the resolution and the no. of colors, the more storage spaces are required to hold the graphic By Netbalone - www.netbalone.com

  10. Vector Graphics • A vector graphic is divided into objects • Each object is defined by the method of drawing it This picture contains 3 objects:a line, a circle and a rectangle By Netbalone - www.netbalone.com

  11. Fill color Radius Line color Line thickness Center How to draw the circle? • The circle is represented by a mathematical formula: Circle(50,100,150,black,1,green) A few bits is enough to save the properties of this circle! By Netbalone - www.netbalone.com

  12. Advantages of using Vector Graphics: • It requires less storage space • When a vector graphic is enlarged, it remains intact (no distortion) Enlarging a Vector Graphic The line is as smooth as before Enlarging a Bitmap Graphic The line thickened & saw-tooth resulted By Netbalone - www.netbalone.com

  13. Common Graphic File Format Bitmap (.bmp) - a common graphic file format;can be read by almost all programs Gif (.gif) - a compressed bitmap file format. It can support up to 256 colors Jpeg (.jpg) - a lossy compressed bitmap file format. But it can support up to 16.7 million colors (because it applies lossy compression, some of the details is lost!) By Netbalone - www.netbalone.com

  14. Jpeg Format (5kB) Gif Format (26kB) By Netbalone - www.netbalone.com

  15. Comparison Table: By Netbalone - www.netbalone.com

  16. How colors are represented? 8-bit color means 28 = 256 different colors 16-bit (High) color means 216 = 65535 different colors 24-bit (True) color means 224 = 16777216 different colors The number of bits used to represent colors is called color depth. By Netbalone - www.netbalone.com

  17. RGB Color Scheme • All colors are made up of 3 primary colors of light: Red (R), Green (G) and Blue (B) • Different intensities of red, green and blue can mix up different colors • In computer, 8 bits are used to represent 256 levels of each of these primary colors By Netbalone - www.netbalone.com

  18. Example: Http://www.phy.ntnu.edu.tw/~hwang/image/rgbColor.html • RGB(255,0,0) = Red • RGB(0,255,0) = Green • RGB(0,0,255) = • RGB(0,0,0) = • RGB(255,255,255) = • RGB(255,0,255) = Blue Black White Magenta By Netbalone - www.netbalone.com

  19. CMYK Color Scheme • For printing, publisher will find CMYK scheme more suitable for ink used. • CMYK represents 4 colors: Cyan, Magenta, Yellow and blacK. By Netbalone - www.netbalone.com

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