原创教学图，不是真实客户照片。
Original teaching image; no client photograph.
原始编码240x160，EXIF Orientation6。只去掉标签的对照仍是240x160；归一化为160x240，上排C/A、下排D/B。
Original encoding240x160 with EXIF Orientation6. Tag-only removal remains240x160; normalization gives160x240 with rowsC/A,D/B.
四角身份定义本例的验收方向，不用字母字形朝向猜测真实人物姿态。真实照片仍需人工判断标签是否正确。
The corner identities define this specimen, not the glyph direction or the intended pose of a real person. Review actual photographs manually.
observed目录为指定版本工具的真实下载，JPEG编码可变化，应比较尺寸和标记，不要求不同编码器文件哈希相同。
observed contains actual downloads from the stated release. Compare dimensions and landmarks; different JPEG encoders need not produce identical hashes.
