Sound,Images and data compression

What is the basic unit of digital images?

• Pixel

• Byte

• Bit

• Sample

Answer explanation

The basic unit of digital images is a pixel. Pixels are the smallest elements of an image, representing a single point of color. Other options like byte and bit refer to data storage, while sample relates to audio, not images.

Which color model is commonly used to store image data?

• CMYK

• RGB

• HSV

• LAB

Answer explanation

The RGB color model is widely used for storing image data as it represents colors through the combination of red, green, and blue light. This model is essential for digital displays and image processing.

How many bits are used in a standard color pixel in a 24-bit image?

• 8 bits

• 16 bits

• 24 bits

• 32 bits

Answer explanation

A standard 24-bit image uses 8 bits for each of the three color channels: red, green, and blue. Therefore, a total of 24 bits are used for a color pixel, making 24 bits the correct answer.

What is the process of converting audio from analog to digital called?

• Sampling

• Quantization

• Encoding

• Modulation

Answer explanation

The process of converting audio from analog to digital is called sampling. It involves taking discrete measurements of the audio signal at regular intervals, which allows for the digital representation of the sound.

Which of the following is used to measure the quality of audio sampling?

• Bit rate

• Sampling rate

• Compression ratio

• File size

Answer explanation

The sampling rate measures how many samples of audio are taken per second, directly affecting audio quality. A higher sampling rate results in better sound fidelity, making it the key metric for audio sampling quality.

How does lossy compression differ from lossless compression?

• Lossy compression does not reduce file size.

• Lossy compression loses some data and reduces quality.

• Lossless compression reduces file size more.

• Lossy compression is reversible.

Answer explanation

Lossy compression reduces file size by permanently removing some data, which can lead to a decrease in quality. This distinguishes it from lossless compression, which retains all original data.

Which file format is typically associated with lossy image compression?

• PNG

• JPEG

• GIF

• BMP

Answer explanation

JPEG is the file format commonly associated with lossy image compression, which reduces file size by discarding some image data. In contrast, PNG and BMP use lossless compression, while GIF is limited to 256 colors.

What is the main purpose of data compression?

• Increase quality

• Reduce file size

• Improve processing speed

• Enhance security

Answer explanation

The main purpose of data compression is to reduce file size, making it easier to store and transmit data efficiently. This helps save storage space and bandwidth, unlike the other options which do not directly relate to compression.

Which technique is used in lossless data compression?

• JPEG

• Huffman coding

• MP3

• MPEG

Answer explanation

Huffman coding is a lossless data compression technique that reduces file size without losing any information. In contrast, JPEG, MP3, and MPEG are lossy compression methods that discard some data to achieve smaller sizes.

Which of the following is an example of lossless image format?

• JPEG

• PNG

• MP3

• MPEG

Answer explanation

PNG is a lossless image format, meaning it retains all image data without compression loss. In contrast, JPEG is lossy, while MP3 and MPEG are audio and video formats, respectively.