The Chinese Academy of Sciences Micro-Expression dataset (CASME II) consists of 255 videos, elicited from 26 participants. The videos are recorded using Point Gray GRAS-03K2C camera which has a frame rate of 200fps. The average video length is 0.34s, equivalent to 68 frames. Each video’s emotion label is annotated by two coders, where the reliability is 0.846.

All the images are cropped to 170×140 pixels. The ground-truth information provided by the database include the emotion state, the action unit, the onset, apex and offset frame indices. The videos are grouped into seven categories: others (99 videos), disgust (63 videos), happiness (32 videos), repression (27 videos), surprise (25 videos), sadness (7 videos) and fear (2 videos).