Patent ID: 8279940

Claim:
A decoder comprising: a processor; and a non-transitory computer-readable storage medium storing instructions that, when executed by the processor, perform a method comprising: determining a quantization parameter from quantization data in a bitstream; generating a luminance scalar according to a piece-wise linear transformation of the quantization parameter, wherein: (i) the luminance scalar equals 8 whenever the quantization parameter falls within the values 1 through 4, inclusive; (ii) the luminance scalar equals 2 times the quantization parameter whenever the quantization parameter falls within the values 5 through 8, inclusive; (iii) the luminance scalar equals the quantization parameter plus 8 whenever the quantization parameter falls within the values 9 through 24, inclusive; and (iv) the luminance scalar equals 2 times the quantization parameter whenever the quantization parameter falls within the values 25 through 31, inclusive; inverse quantizing a DC coefficient of a luminance block of up to four luminance blocks by the luminance scalar to yield an inverse quantized DC coefficient; transforming data of the up to four luminance blocks, including the inverse quantized DC coefficient, according to an inverse discrete cosine transform; and merging data of the up to four luminance blocks to generate image data.