What does jelly mean in photography?

The formation of jelly is determined by the characteristics of the camera itself. Cameras using CMOS sensors mostly use rolling shutters, which are realized by line-by-line exposure of image sensors. At the beginning of exposure, the image sensor scans the exposure line by line until all pixels are exposed. Of course, all the actions are completed in a very short time, which generally will not affect the shooting. But if the object being photographed moves or vibrates rapidly relative to the camera. When shooting with a rolling shutter, the progressive scanning speed is not enough, and the shooting result may be "tilted", "shaken" or "partially exposed". This phenomenon of rolling shutter shooting is defined as jelly effect.