4. “If the size of the file is reduced But the
original data retained. The techniques used
for this purpose are called data compression.”
Different type of data can be compressed e-
g; audio file, video file, image file etc.
5. The main purpose of compression is to
reduce the quantity of the file size but to
keep the quality of the original data
6. It is used to reduce the file sizes of bitmap
graphics
BITMAP GRAPHICS
“Matrix of pixels”
Bitmap graphics can produce some of the
largest file sizes which need to compress for
storing purpose
8. There are two major types of data
compression
1-Lossy compression
2-Lossless compression
9. “If after compression the file cannot be brought
back again then the compression is referred to as
Lossy compression.”
EX:
IMAGE COMPRESSION:
1- GIF( graphic interchange format)
It approaches the compression problem by
reducing the number of colours that can be
assigned to a pixel to only 256
2-TIFF(Tagged image file format)
10. In lossy audio compression the unnecessary
information has been deduced by extensive
testing of the human hearing capacity and
then implemented in different ways by the
different lossy audio compression format to
achieve “utopian” compromise of quality
versus size.
11.
12. 1-Fully taggable with track infos and cover
2-File size reduction to 4-22% of original
size
3-It is a part of music that is un audible to
human ears but they can hear the lost part
4-It use lesser memory as compared to
lossless
13. 1-Does not contain the all original audio
information
2-MP3 not gapless, OGG vorbis however said
to be gapless
3-Conversion any other format only with loss
of audio information
4-Repeated compression and expansion
causes serious artifacts to appear especially
when different algorithm are used.
14. “When a file that has been compressed can be
decoded back into its original form with zero
loss of information.”
15.
16. 1-Corresponds 100% to the original
2-Gapless
3-Fully taggable with track infos and covers
4-Conversion in any other format is possible
without loss of audio information
17. 1-File size reduction only to about 25% (for
piano music) and 70% (for rock music)
2-Uses more memory as compared to lossy
3-Compression ratio is not as good as of
lossy
Editor's Notes
Not used for vectors bcz they give short size file
LZW for Lempel- ziv welsh (after Abraham Lempel, Jacob ziv, Terry Welsh) 1)Lossless 2)Lossless 3)Lossless/ Lossy 4)Lossy 5)
1-dictioary encoding using LZW technique can obtain additional GIF 2-use variation of Run length encoding technique in TIFF
Utopian meaning misali 1-Temporal masking 2-Frequency masking
Taggable meaning tag k qabil
MP3(short pause b/w tracks especially annoying with live tracks)
