Image compression models
- 2. Deals with reducing amount of data required to represent a digital image. The reduction process is the removal of redundant data. Compressed image is decompressed to reconstruct the original image. Data compression → reducing amount of data required to represent in a quality of information.
- 3. Two distinct structures: Encoder : An input image f(x,y) is fed into the encoder which creates the set of symbols from the input data. Decoder : The encoded information is fed into decoder where reconstructed output image f(x,y) is generated.
- 4. Source encoder Channel encoder Channel Channel decoder Source decoder f(x,y) f(x,y) Encoder Decoder
- 5. Three stages of encoding process: Mapper: Transforms input data format designed to reduce interpixel redundancies in the input image. Reversible operation. May or may not reduce the amount of data required to represent the image.
- 6. Quantizer: Reduces the accuracy of the mappers output. Reduces the psychovisual redundancies of the input image. Not reversible operation. It must be omited when error free (lossless) compression is desired.
- 7. Symbol encoder: Creates a fixed-or variable length code to represent the quantizer’s output. Maps the output in accordance with the code. In most cases variable length code is used. Reversible operation.
- 8. It contains two components: A symbol decoder. Inverse mapper. Performs in reverse order . The inverse operations of the source encoder symbol encoder and mapper blocks. The inverse for the quantizer has been left out.
- 9. Mapper Quantizer Symbol encoder f(x,y) → →Channel
- 10. Source decoder Inverse mapper Channel f(x,y) Inverse operations of source encoder and mapper blocks.
- 11. Thank you…