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BINARY IMAGE FILES

BINARY IMAGE FILES. BINARY IMAGE FILES. PART ONE – FILE FORMATS. We’ll do it just one step at a time. First – there are different picture file types jpg tif gif png Each has its own good features and bad features. We’ll do it just one step at a time.

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BINARY IMAGE FILES

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  1. BINARY IMAGE FILES BINARY IMAGE FILES PART ONE – FILE FORMATS

  2. We’ll do it just one step at a time • First – there are different picture file types • jpg • tif • gif • png • Each has its own good features and bad features.

  3. We’ll do it just one step at a time These are all bitmap file types - use pixels to present information on screen - do not scale properly (saw toothing / distortion) There are also vector file types - do not use pixels, they use math equations to interpret the digital information into line work - they can be scaled with no distortion / loss of quality

  4. SAMPLE VECTOR IMAGE • image made up of equations • much smaller file size - about 15 kb • very bad at recording tonal qualities • great for text and line drawings (cartoons, diagrams) • "opens" in CorelDraw, Illustrator and Flash • SAMPLE BITMAP IMAGE • image made up of pixels (picture elements) • much larger file size - about 260 kb • can record different tonal qualities • great for painting, photographs • "opens" in Photopaint, Photoshop • can be imported / inserted into other program documents We’ll do it just one step at a time

  5. We’ll do it just one step at a time • jpg • 24 bit RGB colour (16,700,000 colours!) • better for photos, not line art art • generic – works with almost any software • very web friendly • uses lossy file compression so… • - small file size • - but it can be overcompressed • - it deteriorates with every save

  6. We’ll do it just one step at a time • tif • 24 bit RGB colour (16,700,000 colours!) • generic – works with almost any software • web friendly but size is a problem • uses lossless file compression so… • - huge file size • - does not deteriorate with every save

  7. We’ll do it just one step at a time • gif • 8 bit indexed colour (only 256 colours) • better for line art not as good for photos • generic – works with almost any software • supports transparency • supports animation • very web friendly • uses lossless file compression so… • - does not deteriorate with every save • - but file size is small (only 8 bits)

  8. We’ll do it just one step at a time • png • 24 bit RGB colour (16,700,000 colours!) • supports transparency • generic – works with most software • created for web apps only, cannot support cmyk • uses lossless file compression so… • - does not deteriorate with every save

  9. Is all that 8 bit and 24 bit info just so much… …stuff? 24 bit? 8 bit?

  10. Instead, consider this… Mary Sue and Mary Ellen both want to send a message to Jo. Mary Ellen Mary Sue Jo

  11. BUT… Mary Sue can only use 8 letters to write her message to Jo. She’ll only be able to say a very limited message.

  12. While… Mary Ellen can use 24 letters to write her message to Jo. Who can send more information? Who can say more and offer more details? Obviously Mary Ellen – 24 letters gives you more to work with and that makes a huge difference!

  13. So… 8 letters would let you say a little but it would be really limiting 24 letters would give you a lot more to work with and that would be very effective.

  14. Now then… Think of binary code as being like those letters. 8 bit code uses 8 1’s & 0’s – it works but it’s pretty limited. 24 bit code uses 24 1’s and 0’s – that’s a lot more to work with and offers a lot more possibilities. This is known as BIT DEPTH , the number of 1’s and 0’s in the file’s binary code. More 1’s and 0’s = more info = better images.

  15. Yeah, so? 8 bit code can make 256 colours using just 8 1’s and 0’s.

  16. But watch this! 24 bit code – that’s just 24 1’s and 0’s - can make 16,700,000 colours! Now… THAT’S IMPRESSIVE!!!

  17. Hmm-m-m-m… It works by using the power of exponents – in this case, 23 for 8 bit and 223 for 24 bit. Too confusing? Just think about writing with just 8 letters or 24 letters. Substitute 1’s and 0’s for the letters and you’ll have the basic idea.

  18. Lossy versus lossless… huh? • File compression – • we “squeeze” files to make them smaller • Two ways to do this – • lossy • lossless

  19. Lossy versus lossless… huh? • Lossy • removes duplicate information • can be seriously compressed • means file can be overcompressed (destroyed) • deteriorates with every save / compression – decompression • Example – a 2500 kb tif file could be 150 kb jpg, without any extra compression

  20. Lossy versus lossless… huh? • Lossless • preserves appearance of original image • cannot compress to a very small file • does not deteriorate with every save • Tiff uses lossless compression – fabulous quality but huge file size.

  21. Review time List the types of image files discussed. List their strengths and weaknesses. Give examples of where / when each would be used – and explain why.

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