if d.comp[1].h != h || d.comp[1].v != v {
					return errUnsupportedSubsamplingRatio
				}
			}

		case 4:
			// For 4-component images (either CMYK or YCbCrK), we only support two
			// hv vectors: [0x11 0x11 0x11 0x11] and [0x22 0x11 0x11 0x22].
			// Theoretically, 4-component JPEG images could mix and match hv values
			// but in practice, those two combinations are the only ones in use,