(i) Huffman code:

• Huffman coding is a lossless compression variable length coding technique.
• It is frequency dependant technique.
• In Huffman coding characters that occur most often are assigned few bits while the characters that occur rarely are assigned more bits.

(ii) Lossy predictive coding:

• DPCM is Lossless Predictive Coding.
• In DPCM, Interpixel redundancy exists due to correlation between the neighboring pixels in an image. Spatial redundancy implies that there is a relationship between pixels in an image.
• To reduce the inter-pixel redundancy the difference between adjacent pixels is used to represent an image by DPCM.

(iii) Transform coding

• In transform coding a reversible linear transform is used to map the image into a set of transform coefficients which are then quantized and coded.
• For most images, a significant number of coefficients have small magnitudes and can be coarsely quantized or discarded entirely with little image distortion.