Initializes a new instance of the DctEncoder class.
public DctEncoder(int quality, DctChromaSubsampling chromaSubsampling)
The quality, 1 to 100: the Annex K quantization tables scaled by 5000 / quality percent below 50 and by 200 - 2 x quality
percent from 50, each value rounded and kept within 1 to 255 (libjpeg's jpeg_set_quality with baseline tables).
How much chrominance is subsampled when colour is transformed.
ITU-T T.81 Annex K.1 (Tables K.1 and K.2), §A.1.1 (sampling factors).