Why are the photos taken by Canon cameras in the conference room so dark?

The photos taken by Canon camera in the conference room are very dark. If manual files are used, the exposure time setting is not enough. If you use automatic gear, except that the camera does not perform well in low light, according to the principle of photometry, the whole photo will generally not be dark. The common problem is that the background is bright and the people are dark. The solution is to minimize the proportion of bright background in the picture when framing and composing. It is best not to have a bright background when people's illumination is already very dark.