JPEG compression uses a lossy algorithm that divides the image into blocks of pixels. These blocks are of what size?

JPEG compression uses a lossy algorithm that divides the image into blocks of pixels. These blocks are of what size?

• A. 4x4 pixels
• B. 8x8 pixels
• C. 16x16 pixels
• D. 32x32 pixels

Answer: (B)

JPEG uses a block-based approach where the image is divided into small square sections and the discrete cosine transform is applied to each one. The size of those blocks is 8 by 8 pixels. This per-block processing is what makes the compression lossy: the 8x8 DCT coefficients are quantized, discarding some high-frequency information, and then encoded. Choosing 8x8 is a practical balance that preserves detail while allowing efficient coding and manageable artifacts. Smaller blocks would add overhead without much gain, while larger blocks would blur fine detail and produce visible blocking effects.

JPEG uses a block-based approach where the image is divided into small square sections and the discrete cosine transform is applied to each one. The size of those blocks is 8 by 8 pixels. This per-block processing is what makes the compression lossy: the 8x8 DCT coefficients are quantized, discarding some high-frequency information, and then encoded. Choosing 8x8 is a practical balance that preserves detail while allowing efficient coding and manageable artifacts. Smaller blocks would add overhead without much gain, while larger blocks would blur fine detail and produce visible blocking effects.