An implementation of image codec based on H.264 and H.265

1. Image Codec Development
James Huang

2. Outline
● Flow Chart
● Intraprediction
● DCT & Quantization
● Entropy Coding
● Result

3. Flow Chart

4. Intraprediction
● 4*4 block intra
◦ 9 modes(H.264)

5. Intraprediction
● No reference pixel => set it to 128(average)
● Mode choosing
=> by MSE and choose the smallest
● Block prediction order
⇒ From top to bottom, left to right
● Those pixels that can not form a 4*4 block
● Get the residue and chosen mode in each
block

6. DCT & Quantization
● Take the residue and do 4*4 integer
transform
● Choose Qstep(1~16)
◦ Quantize the transformed matrix
◦ Match the number of bits
◦ Choose the Qstep that has the smallest
MSE

7. Entropy Coding
● Arithmetic Coding
◦ Residue
◦ Modes
◦ Quantization Steps

8. Entropy Coding

9. Result
Original Raw Image Compressed Image (Qstep = 4)

10. Result
Compressed Image (Qstep = ) Bitrate-PSNR Curve of 5 different images