Lossless CompressionIt optimizes data storage of files and adopts specific algorithms to encode repeated data. The original file can be fully restored without any content change. For digital images, no details will be lost. Only redundant data is eliminated during lossless coding. The reconstructed image after decoding stays completely identical to the original one.

Lossy CompressionThis method alters image content. It retains most luminance information while merging hue and saturation data with adjacent pixels. The compression ratio varies according to merging degree. It delivers a high compression rate at the cost of degraded image quality. The decoded image cannot be perfectly restored and features certain distortion, yet maintains similar visual performance. It serves as an effective coding approach for high compression ratio.