Digital Image and Audio

1. Digital Image and Audio Course: CIS 3003 Fundamental of Information Technology

2. Objective • Understand how image is captured by camera and scanner. • Understand how image is displayed by monitor and projector. • Learn about various image and video format.

3. Mosaic Image Information Technology in Theory

4. Pixelized Images Information Technology in Theory

5. A Bitmap Image Information Technology in Theory

6. Vector Graphics • Images are represented in the form of mathematical expressions • Parameters can include attributes such as orientation, length, width, and color • Takes up less storage space than bitmap images • Can be easily scaled without degradation in quality and resolution • Useful for representing geometric shapes but not effective for photographs Information Technology in Theory

7. Capturing Color Images Using Digital Cameras • Lens system • Sensor array • Filter system • Memory • Processor • Software • Viewing screen Information Technology in Theory

8. Capturing Color Images Using Digital Cameras • Lens system is used to focus the image onto a small sensor array called a CCD (charge-coupled device) array • These sensors detect light and produce electricity proportional to the intensity of that light Information Technology in Theory

9. The CCD Array Information Technology in Theory

10. The Additive Color Model Information Technology in Theory

11. The Additive Color Model Information Technology in Theory

12. Spinning Disk Filter Information Technology in Theory

13. Image Resolved Into Basic Color Components Information Technology in Theory

14. Color Palette and Corresponding Binary Codes Information Technology in Theory

15. Spinning Disk Filter vs. Bayer Filter Information Technology in Theory

16. Size of image captured by digital camera Calculate the number of megabytes in a color image captured by a digital camera that can produce images with 2272 x 1704 pixels with a bit depth of 24.

17. Size of image captured by scanner Calculate the number of megabytes produced at the output of a 1200 x 2400 dpi scanner that has scanned an 8.5 x 11-inch photograph in true color. dpi – dots per inch; each dot a pixel. True color – 24 bits

18. Image Resolution Defined by Spatial and Brightness Resolutions.

19. Spatial Resolution • pixels per unit length • Affected by image size, viewing distance

20. Spatial Resolution and Image Size How many KB a 300 pixels by 300 pixels color image with bit depth of 24 bits has if its spatial resolution reduced to 200 pixels by 200 pixels.

21. Brightness Resolution • Bit depth; how many bits used to describe color of each pixel. • Affected by human ability to distinguish color; about 16 million colors or 24 bits.

22. Brightness Resolution andImage Size How many KB a 50 pixels by 50 pixels color image with bit depth of 24 bits has if its brightness resolution reduced to 12.

23. Digital Video • Motion is emulated by showing images in rapid succession • Visual persistence causes us to see an image for a split second after closing our eyes • Human eyes can process approximately 20 images per second before losing the ability to distinguish the transition of one image to another • Motion picture industry standard uses 24 frames per second (fps) to create a continuous motion effect Information Technology in Theory

24. Digital Video • Motion is emulated by showing images in rapid succession • Visual persistence causes us to see an image for a split second after closing our eyes • Human eyes can process approximately 20 images per second before losing the ability to distinguish the transition of images. • Motion picture industry standard uses 24 frames per second (fps) to create a continuous motion effect.

25. Size of Digital Movie Calculate the number of gigabytes of a two-hour digital movie with 24 fps and each frame is an image of 512 pixels by 512 pixels with 9-bit binary code.

26. Image Formats • JPEG: Joint Photographic Experts Group (.jpeg or .jpg) • True color or 24-bit color depth. • Lossy and lossless compression • Supported in web browser. • GIF: Graphics Interchange Format (.gif) • Provides simple animation effect • 8-bit color depth or 256 colors • Supported in web browser.

27. Image Formats • PNG: Portable Network Graphics (.png) • Lossless compression • Color bit depth higher than GIF • Has an non-backward compatible animation extension. • Supported in browser (not the animation extension). • Not patented like GIF

28. Image Formats • BMP: Bitmap Picture (.bmp) • No compression; store images as bit maps • True color • Large file size; not supported in browser • TIFF: Tagged Image File Format (.tif or .tiff) • Frequently used in printing and publishing • Can include multiple images • Support range of color depth including true color • Use tag to describe image properties • Not commonly used on the Web.

29. Video Formats • MPEG: Moving Pictures Experts Group • Reduce file size by storing differences between successive frames. Key frames are used as a base to the difference. • Used in DVD, digital broadcast, and movie file uploaded to the Web. • AVI: Audio Video Interleaved • Does not support high resolution and viewed in small viewing window. • Played in Windows operating environment.

30. Video Formats • WMV: Windows Media Video • Able to be played in Windows Media Player software installed on the Microsoft devices such as Zune and Xbox • MOV: Apple • Developed by Apple and be played with Apple’s Quicktime software.

31. Display CRT LCD

32. CRT Display • Color of a bit is produced by a group of three types of phosphor that glow in three basic color. • Image is produced by an electronic beams that is controlled by magnetic mechanism.

33. TFT LCD Display • Color of a bit is produced by a group of three types of color filter crystals, each filters one basic color. • A crystal changes a vertical polarized light to a horizontal polarized. • Electricity untwist crystal

34. LED LED • Used in large outdoor billboards or traffic sign. • Each color is made of LED’s that emit red, green, and blue light. • Color intensity is changed by intensity of electricity applied to LED.

35. Other Display Technologies LED • Used in large outdoor billboards or traffic sign. • Each color is made of LED’s that emit red, green, and blue light. • Color intensity is changed by intensity of electricity applied to LED. Plasma • Used in TV. Thin like a LCD but … • uses phosphor and thus provides wider viewing angle, higher contrast, and better brightness than LCD.

36. LED

37. Technical Characteristics of Display Device • Spatial resolution: Number of columns of pixels multiplied by number of rows of pixels • Pixel/dot pitch: space between pixels • Screen size: Diagonal distance • Aspect ratio: 4:3 or 16:9 • Brightness resolution: bit depth • HDTV: 5 times more pixels per frame

38. Pixel Density of a Monitor Assuming a monitor has has a spatial resolution of 1024 by 768 with screen size 15 inches. What is spatial density or pixels per inch? Assuming aspect ratio of 4:3

39. DLP Projector • Use tiny mirror to reflect light to the projector screen • Processor control the direction of reflection. • Spinning disk like filter controls the color the reflected light – persistent vision. • Color intensity – how long a filter stays in front the mirror.

40. Summary • Cameras and scanners use CCD to capture images. • Monitors and projectors use light source, color filters, and electricity to control how color display an image • Discuss various image and video format