10 Questions
What is the primary difference between lossless and lossy compression?
The reversibility of the compressed data
What is the drawback of using lossy compression on an image file?
Some of the original information is lost
Which of the following is a characteristic of lossless compression?
Reversible compression
What is the purpose of decompression in file compression?
To restore the original file from its compressed form
Which type of compression is suitable for applications where data integrity is crucial?
Lossless compression
What is run-length encoding?
A type of file compression algorithm
What happens to the original information when a file is compressed using lossy compression?
It is permanently eliminated
What is the advantage of using lossless compression on a digital file?
It preserves the original data
What is the main difference between compression and decompression?
Compression reduces file size, while decompression increases file size
What is the purpose of file compression?
To reduce the file size and/or change various attributes
Study Notes
Image Compression Techniques
- JPEG image files are commonly used for photographs and complex still images on the web with no transparency.
- JPEG compression uses lossy compression, allowing the creator to decide how much loss to introduce and balance between file size and image quality.
Algorithms for Compression
- Lossless compression algorithms:
- Run Length Encoding
- Lempel-Ziv-Welch (LZW)
- Huffman Coding
- Arithmetic Encoding
- Lossy compression algorithms:
- Transform Coding
- Discrete Cosine Transform
- Discrete Wavelet Transform
- Fractal Compression
Advantages and Drawbacks of Lossless Compression
- Key benefit: retain file quality while achieving smaller file size.
- Drawback: larger file sizes required to maintain post-compression quality.
Characteristics of Lossy Compression
- Removes unnecessary data, not restored after decompression.
- Known as irreversible compression.
- Data loss is not usually noticeable, but increases with compression.
Applications of Lossless and Lossy Compression
- Lossless compression is mainly used for:
- images
- sound
- text
- detailed product images, photography showcases, text files, and spreadsheet files.
- Lossy compression is mainly used for:
- images
- audio
- video
- audio and video files where some information loss is acceptable.
Definition of Lossless and Lossy Compression
- Lossless compression: every bit of original data remains after decompression.
- Lossy compression: reduces file by permanently eliminating certain information, restoring some data after decompression.
File Compression
- Digital files are compressed to reduce size and/or change attributes (file type, dimensions, resolution, bit depth).
- Compression reduces file size, often with minimal loss of information.
- Can be either lossless or lossy.
Learn about the JPEG image file format, its use of lossy compression, and the trade-off between file size and image quality. Understand how algorithms can be adjusted to balance compression ratio and image quality.
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