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Ignatius Seminar Mahendran Velauthapillai

Ignatius Seminar Mahendran Velauthapillai. Manipulation. Manipulation. Information can be represented in many ways, that is multiple representation Eg : Numbers Same representation can mean different information Eg : ? . How does the Machine know what information is represented?

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Ignatius Seminar Mahendran Velauthapillai

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  1. Ignatius SeminarMahendran Velauthapillai Manipulation

  2. Manipulation • Information can be represented in many ways, that is multiple representation Eg: Numbers • Same representation can mean different information Eg: ?

  3. How does the Machine know what information is represented? Example: Pictures: *.jpg, *.bmp ,*.png Sound: wav, mp3, ogg, gsm, dct, flac, etc…

  4. JPEG File Interchange Format File Format Summary • Also Known As: JFIF, JFI, JPG, JPEG http://www.fileformat.info/format/jpeg/egff.htm

  5. File Organization • Both JPEG and JFIF data are byte streams, always storing 16-bit word values in big-endian format. JPEG data in general is stored as a stream of blocks, and each block is identified by a marker value. • The first two bytes of every JPEG stream are the Start Of Image (SOI) marker values FFh D8h. In a JFIF-compliant file there is a JFIF APP0 (Application) marker, immediately following the SOI, which consists of the marker code values FFh E0h and the characters JFIF in the marker data, as described in the next section. In addition to the JFIF marker segment, there may be one or more optional JFIF extension marker segments, followed by the actual image data.

  6. File Details • Although JFIF files do not possess a formally-defined header, the SOI and JFIF APP0 markers taken together act as a header in the following marker segment structure:

  7. BYTE SOI[2]; /* 00h Start of Image Marker */ • BYTE APP0[2]; /* 02h Application Use Marker */ • BYTE Length[2]; /* 04h Length of APP0 Field */ • BYTE Identifier[5]; /* 06h "JFIF" (zero terminated) Id String */ • BYTE Version[2]; /* 07h JFIF Format Revision */ • BYTE Units; /* 09h Units used for Resolution */ • BYTE Xdensity[2]; /* 0Ah Horizontal Resolution */ • BYTE Ydensity[2]; /* 0Ch Vertical Resolution */ • BYTE XThumbnail; /* 0Eh Horizontal Pixel Count */ • BYTE YThumbnail; /* 0Fh Vertical Pixel Count */

  8. Audio file format • From Wikipedia, the free encyclopedia • An audio file format is a file format for storing digital audio data on a computer system. This data can be stored uncompressed, or compressed to reduce the file size. It can be a raw bitstream, but it is usually a container format or an audio data format with defined storage layer.

  9. 1 Types of formats • 1.1 Uncompressed audio formats WAV, AIFF, AU or raw header-less PCM; • 1.2 Lossless compressed audio formats MPEG4 SLS, MPEG4 ALS, WMA lossless • 1.3 Lossy compressed audio formats MP3, AAC, WMA lossy

  10. http://www.nch.com.au/acm/formats.html • http://www.kendavies.net/resources/audioformats/ ( some history 2001) http://www.audible.com/audioformats http://www.vcu.edu/mdcweb/selfstudy/monographs/formats.htm http://en.wikipedia.org/wiki/MP3 (must read)

  11. Video • http://en.wikipedia.org/wiki/Video • http://www.mediacollege.com/video/format/ • http://gizmodo.com/5093670/giz-explains-every-video-format-you-need-to-know • http://anythingbutipod.com/2008/11/video-format-roundup/ • http://en.wikipedia.org/wiki/Video • http://www.mediacollege.com/video/format/ • http://gizmodo.com/5093670/giz-explains-every-video-format-you-need-to-know • http://anythingbutipod.com/2008/11/video-format-roundup/

  12. Once you have a representation, how do you manipulate them? • You have to define what is allowed and what is not allowed. • You define operation:

  13. Operations • Operations that you perform, depends on the information that you want to process. • Numbers: addition, subtraction, …….. • Images: Scaling, rotation, sharpen, blur, etc..

  14. Operations continued.. • Sound: remove noise, add other sound, increase volume, compress, …. • Video: Compress, remove noise, correct frames, …

  15. Arithmetic • Using a series of half adders • Addition: first lecture • Subtraction: ? • Multiplication: Shift and add for small numbers • Division: Reverse of multiplication (find out)

  16. Image Manipulation • Rotation • Scaling • Invert • etc…. ???????

  17. Rotation • How does the computer rotate an image by 90 degrees right? (Note this is not the same as rotating at a point)

  18. Scaling • How do you double the image • How do you make it half

  19. Invert • Original image After the colors were inverted

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