| JMETHOD(void, start_pass,(j_compress_ptr cinfo)) | jpeg_downsampler | |
| JMETHOD(void, downsample,(j_compress_ptr cinfo, JSAMPIMAGE input_buf, JDIMENSION in_row_index, JSAMPIMAGE output_buf, JDIMENSION out_row_group_index)) | jpeg_downsampler | |
| need_context_rows | jpeg_downsampler |