Data compression

விளையாடிக் கற்றுக்கொள்ளுங்கள்

ஆற்றல் சம்பாதிக்க இந்த கேள்விகளுக்குப் பதிலளியுங்கள், பின்னர் மீன் பிடித்து ஆராயுங்கள். கணக்கு தேவையில்லை.

கல்வியாளர்களுக்கு: Data compression (Computer Science, Data Representation)-க்கான தயாரான பாட ஸ்லைடுகள், திருப்புதல் குறிப்புகள் — உங்கள் பாடத்தில் அவற்றைப் பயன்படுத்தவும், அல்லது கற்பவர்கள் நேரலை விளையாட்டாக விளையாடும் ஊடாடும் வகுப்பு செயல்பாடாக தலைப்பை இயக்கவும்.

பாட குறிப்புகள்ஸ்லைடுகள்பயிற்சி கேள்விகள்

பாட குறிப்புகள்

Why compress?

Compression makes files smaller: less storage, faster transfer and lower bandwidth costs.

Packing and restoring files

Lossy compression

Lossy compression permanently discards information, so the exact original cannot be reconstructed from the compressed representation alone.
Examples include standard lossy JPEG images, MP3 audio and lossy H.264 video. MP4 is a container; its codec determines compression.

Lossless compression

Lossless reduces size without losing any data; the original can be perfectly restored. Used for PNG, ZIP, FLAC and text where accuracy matters.

Lossless and lossy compression

Run-length encoding (RLE)

Replaces repeated values with a count and the value. AAAABBBCC → 4A3B2C. Works well when many repeats occur (simple images). May not help if there are few repeats.

Run-length encoding

Huffman coding

Huffman coding builds variable-length prefix codes using symbol frequencies, normally giving common symbols shorter codes.
Encoded symbol data can require fewer bits than a fixed-length code; any codebook or tree overhead also contributes to the stored file size.

Choosing

Use lossy for photos, music and video where small quality loss is acceptable; use lossless where exact data matters (documents, program code).

ஸ்லைடுகள்

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பதிவு செய்க — இலவசம்உள்நுழைக

பயிற்சி கேள்விகள்

இலவச முன்னோட்டம் — 32-இல் 8 கேள்விகள். அனைத்தையும் பார்க்க பதிவு செய்யவும்.

1.What is compression?
Easy
- Areducing the size of a file
- Bencrypting a file
- Ccopying a file
- Ddeleting a file
2.What does lossy compression do?
Easy
- Apermanently removes some data
- Bkeeps all data
- Cencrypts data
- Dcopies data
3.What does lossless compression do?
Easy
- Areduces size without losing data
- Bremoves data permanently
- Cincreases size
- Dhides data
4.Which file type uses lossy compression?
Easy
- AMP3
- BZIP
- CPNG
- DFLAC
5.Which file type uses lossless compression?
Easy
- APNG
- Bstandard lossy JPEG
- CMP3
- Duncompressed PCM audio
6.What is the RLE of WWWWBBBWW?
Easy
- A4W3B2W
- B4W3B
- CWBW
- D9W
7.What does 3A2B decode to?
Easy
- AAAABB
- BAB
- C32AB
- DAAAB
8.What does Huffman coding use?
Easy
- Ashorter codes for common characters
- Bequal codes
- Crandom codes
- Dno codes

மேலும் கேள்விகள்

9.When is lossless needed?
Easy
- Awhen exact data must be kept
- Bfor music
- Cfor movies
- Dfor photos only
10.Why do JPEG images take less space than uncompressed ones?
Easy
- Asome detail is removed
- Bthey have fewer colours always
- Cthey are smaller pictures
- Dthey are encrypted
11.Which compression is best for a document where every letter matters?
Medium
- Alossless
- Blossy
- Cnone
- Dboth
12.Which method is commonly used for music streaming when reducing data transfer is a priority and some loss of fidelity is acceptable?
Medium
- Alossy
- Blossless only
- Cnone
- Dhash
13.Why might RLE give a bigger file?
Medium
- Athere are few repeated values
- Bthere are many repeats
- Cthe file is empty
- Dit is lossless
14.What is the RLE of ABCD?
Medium
- A1A1B1C1D
- B4ABCD
- CABCD
- DA4
15.What is a disadvantage of lossy compression?
Medium
- Aquality is reduced permanently
- Bthe file is larger
- Cit is not smaller
- Dit is slower
16.What is an advantage of lossless compression?
Medium
- Athe original can be perfectly restored
- Bthe file is smallest
- Cquality is lost
- Dit is lossy
17.A website needs a small photographic image and accepts some loss of fine detail. Which option suits that requirement?
Medium
- Alossy such as JPEG
- Blossless only
- Cneither
- Dboth identical
18.A string of 100 identical letters is stored using RLE. How is it represented?
Medium
- A100 followed by the letter
- B100 letters
- C1 letter
- D100 zero
19.Why does Huffman coding reduce the average bits per character?
Medium
- Afrequent characters use fewer bits
- Ball characters use more bits
- Cit uses 8 bits
- Dit removes characters
20.Why can't lossy compression be reversed to the original?
Medium
- Ainformation has been discarded
- Bit is encrypted
- Cit is stored
- Dit is copied
21.What is bandwidth?
Easy
- Athe amount of data that can be transferred per second
- Bstorage size
- Cfile type
- Dscreen size
22.What does ZIP do?
Easy
- Acompresses files without loss
- Bdeletes files
- Cencrypts files
- Dcopies files
23.What is an MP4 file?
Medium
- Aa container that can hold audio and video streams
- Ba plain-text document format
- Can executable program instruction
- Da compression method guaranteed to be lossless
24.What is a frequency tree used for?
Medium
- Abuilding Huffman codes
- Bsorting
- Csearching
- Dencrypting
25.Lossy compression permanently removes data.
Easy
True or false?
26.Lossless compression can restore the original.
Easy
True or false?
27.PNG uses lossy compression.
Easy
True or false?
28.RLE replaces repeated values with counts.
Easy
True or false?
29.Compression always makes files larger.
Medium
True or false?
30.Which use lossy compression in the forms specified here?
Medium
- Astandard lossy JPEG images
- BMP3 audio
- Clossy H.264 video
- Dlossy AAC audio
- EZIP archives
31.Which can be benefits of successfully reducing a file’s size by compression?
Medium
- Aless storage needed
- Bshorter transfer time at a fixed data rate
- Cfewer bytes transmitted
- Dreduced storage or transfer cost
- Ehigher resolution automatically
32.Apply run-length encoding to the string WWWWWBBBWWW.
Medium

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இந்த தலைப்பிற்கான ஒவ்வொரு கேள்வியையும், ஸ்லைடுகளையும், ஃப்ளாஷ் கார்டுகளையும் மற்றும் திருப்புதல் குறிப்புகளையும் பார்க்க இலவச கணக்கை உருவாக்கவும்.

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