| 摘要 |
A system and method of image compression comprising receiving a frame of pixel tiles / blocks, determining the available bandwidth of each pixel block and, for each colour channel of each pixel block, transforming the pixel data to create a series of coefficients and performing a quantisation of the series of coefficients using a quantisation level selected according to the bandwidth and coefficient size. Bandwidth may be expressed as a bit rate per pixel. The available bandwidth may be varied for different tiles of the same pixel tile. The transform may comprise a Haar transform or a Discrete Wavelet Transform. Entropy coding of the quantised series of coefficients may be performed. Selecting the quantization level may comprise mapping the coefficient size to one of a plurality of predetermined levels and using a quantisation level pre-assigned to the mapped level. When bandwidth is restricted this flexible compression method allows different types of images to be compressed. |
