Podcast
Questions and Answers
Which of the following strategies is least effective for reducing the file size of a digital image?
Which of the following strategies is least effective for reducing the file size of a digital image?
- Lowering the resolution of the image.
- Decreasing the number of colors used in the image.
- Applying lossless compression techniques. (correct)
- Converting the image to a vector graphic format, such as SVG.
A digital audio file is compressed using perceptual music shaping. Which of these statements best describes the impact of this process?
A digital audio file is compressed using perceptual music shaping. Which of these statements best describes the impact of this process?
- It maintains perfect audio fidelity while minimizing file size.
- It significantly reduces file size, but introduces noticeable distortion to the audio.
- It increases the dynamic range of the audio, making quieter sounds more audible.
- It reduces file size by removing audio frequencies outside the typical range of human hearing. (correct)
When converting a WAV audio file to MP3 format, a significant reduction in file size is observed. Which of the following is the primary reason for this reduction?
When converting a WAV audio file to MP3 format, a significant reduction in file size is observed. Which of the following is the primary reason for this reduction?
- MP3 uses lossless compression algorithms, while WAV is uncompressed.
- MP3 employs psychoacoustic modeling to discard audio data inaudible to human ears. (correct)
- MP3 files inherently have a lower bit depth than WAV files.
- MP3 only stores the vocal tracks, discarding instrumental elements.
Consider a text file containing a long sequence of repeated characters. Which compression technique would be most efficient at reducing the file size?
Consider a text file containing a long sequence of repeated characters. Which compression technique would be most efficient at reducing the file size?
Which of the following adjustments to audio recording parameters will result in the smallest file size after compression, assuming all other factors remain constant?
Which of the following adjustments to audio recording parameters will result in the smallest file size after compression, assuming all other factors remain constant?
Which of the following is the primary reason for compressing files?
Which of the following is the primary reason for compressing files?
A software company requires a compression technique for distributing software updates. Which characteristic is MOST crucial for the chosen method?
A software company requires a compression technique for distributing software updates. Which characteristic is MOST crucial for the chosen method?
Which of these scenarios would be MOST appropriate to use Lossy compression?
Which of these scenarios would be MOST appropriate to use Lossy compression?
Abdullah is using RLE (Run Length Encoding) to compress a black and white bitmap image. If a row of the image contains 12 white pixels followed by 5 black pixels, how would this sequence be represented using RLE, given that 3B is the code for white and 1A is the code for black?
Abdullah is using RLE (Run Length Encoding) to compress a black and white bitmap image. If a row of the image contains 12 white pixels followed by 5 black pixels, how would this sequence be represented using RLE, given that 3B is the code for white and 1A is the code for black?
A digital artist wants to reduce the files size of their high resolution digital painting before sending it to their client. They decide to reduce the bit depth. What impact will the file compression have on the image?
A digital artist wants to reduce the files size of their high resolution digital painting before sending it to their client. They decide to reduce the bit depth. What impact will the file compression have on the image?
Which of the following image compression methods is lossy?
Which of the following image compression methods is lossy?
A photographer needs to send a large batch of high-resolution photographs to a client with a strict file size limit. They want to minimize the loss of quality while achieving the required compression. Which combination of methods would be MOST effective?
A photographer needs to send a large batch of high-resolution photographs to a client with a strict file size limit. They want to minimize the loss of quality while achieving the required compression. Which combination of methods would be MOST effective?
Which of the following methods is lossless?
Which of the following methods is lossless?
Flashcards
Lossy Compression
Lossy Compression
A method of reducing file size by removing some data, often imperceptible to the user.
MP3 Format
MP3 Format
A digital audio format that uses lossy compression to reduce file size significantly while retaining perceived sound quality.
Perceptual Music Shaping
Perceptual Music Shaping
A technique that removes sounds not easily heard by the human ear to compress audio files.
Reduce Sampling Rate
Reduce Sampling Rate
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Run-Length Encoding (RLE)
Run-Length Encoding (RLE)
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Compression
Compression
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Lossless Compression
Lossless Compression
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When to use Lossless
When to use Lossless
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When to use Lossy
When to use Lossy
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JPEG Compression
JPEG Compression
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Reducing Bit Depth
Reducing Bit Depth
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Study Notes
Compression Overview
- Compression reduces file sizes.
- Large data files require compression for faster transmission and storage.
Types of Compression
- Lossless Compression: Data is not lost; the compressed file can be decompressed to the original.
- Lossy Compression: Data is lost; the decompressed file is not identical to the original. Lossy compression reduces file size more significantly than lossless.
Applications of Lossy and Lossless Compression
- Lossy: Used when data accuracy is not critical (e.g., images, audio).
- Lossless: Used when data accuracy is essential (e.g., source code).
Scenario Based Question
- Abdullah wants to compress source code. Lossless compression is the appropriate technique, as data loss would negatively affect the program.
Compressing Photographs
- Lossy compression is suitable for photographs emailed to a friend since file size is important for faster transmission. Features such as color reduction can be used without discernible change to the user.
Compressing Bitmap Images
- Run-length Encoding (RLE) is a lossless compression technique for bitmap images.
Example Bitmap Image Compression
- A black and white bitmap image with black as 1A and white as 3B can be compressed by recording the color codes and their repetition counts.
JPEG Compression
- JPEG is a lossy compression technique.
- It removes parts of the image not noticeable to the human eye.
- Other methods such as reducing color depth, or image resolution also contribute to lossy compression.
Lossy Methods for Compressing Images
- Reducing Bit Depth: Reduces the number of bits per pixel, resulting in fewer bits for each pixel.
- Reducing Number of Colors: Fewer colors mean fewer bits needed to store each color.
- Reducing Image Resolution: Fewer pixels per unit measurement requires less binary storage.
Vector Image Compression
- Vector images (.svg) are defined in XML text files which allows them to be compressed.
Compressing Audio
- MP3 utilizes audio compression, often including the use of perceptually music shaping.
Perceptual Music Shaping
- Removes sounds outside the human hearing range (20 Hz to 20,000 Hz).
- If two sounds are played simultaneously, the louder one may mask the softer sound.
Lossy Sound Compression Methods
- Reducing Sampling Resolution: Reduces the number of bits per sample.
- Reducing Sampling Rate: Reduces the number of samples per unit time.
- Perceptual Music Shaping: Removes parts of sound not noticeable to the human ear.
MP3 Compression
- MP3 is a lossy compressed format which uses psycho-acoustic modeling and perceptual music shaping.
- It removes sounds that are not typically audible to a human ear, and prioritizes sounds within the human hearing range.
- In cases of multiple sound frequencies playing simultaneously, the softer sound is discarded.
Compressing Text Files
- Run-length Encoding (RLE) can be used to compress text files. ASCII values are used to represent and count the repetitive characters in the text.
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Description
Explore the two primary data compression methods: lossy and lossless. Lossless compression preserves original data, while lossy sacrifices some data for smaller file sizes. Learn the applications of each type and when to use them.
