1. JPEG Image Compression
BITS GC 331
Computer Projets
HemanthKumar Mantri
2004S3P7549

2. JPEG Image Compression
JPEG: Joint Photographic Experts Group.
JPEG: compression algorithm, NOT a file format. The original JPEG format
was JFIF and later SPIFF. Current popular choices include C-Cube
JFIF; Adobe TIFF/JPEG.
4-step process:
1. Transforming RGB to YCbCr, separating intensity from color
2. Identifying redundant data using a Discrete Cosine Transformation
(DCT)
3. Quantizing remaining data
4. Encoding the result to minimize storage requirements

34. RGB YCbCr

35. After DCT After Quantisation

36. Regenerated from Bits

37. Inverse Quant. IDCT

38. YCbCr New RGB New

39. Original 37.7 KB Regenerated 29.3 KB Difference

40. Compression performance
JPEG:
} 10:1 to 20:1 compression without visible loss (effective storage
requirement drops to 1-2 bits/pixel)
} 30:1 to 50:1 compression with small to moderate visual
deterioration
} 100:1 compression for low quality applications

42. That’s all
And
Thank You