Why is the white background gray?

The reason is that the white balance is not adjusted well.

There are light (ambient reflected light), white balance of camera, lens of camera, photosensitive element of camera, soft (real) part of camera, color difference of display, etc. And the color filter may also cause color difference.

Increasing the power of background light will make the background overexposed and white. Natural light is suitable for people who can't turn on the light. There is too little light without a studio. Its color temperature and light will change constantly, and it can only work during the day.

If the white balance of the camera is inconsistent with the color temperature of the light, there will be color difference. White balance uses Kodak's standard whiteboard, and white paper is not allowed, because the white of paper is very inaccurate, and the white of white paper is different.

Doing white balance is to manually focus the correct exposure of the full whiteboard under the customized white balance menu to shoot ambient light, and it is good to prompt success. Setting it to white balance will get correct color reproduction. In some shooting occasions, it is more appropriate to use a lens cover called white balance to do this white balance.

Extended data:

White balance is an index to describe the white accuracy of the mixed red, green and blue primary colors in the display. White balance is a very important concept in the field of TV camera shooting, through which a series of problems such as color restoration and tone processing can be solved.

White balance is produced by the true color reproduction of electronic images. It was used in the field of professional photography earlier, and now it is also widely used in household electronic products (household cameras, digital cameras). However, the development of technology makes white balance adjustment easier and easier, but many users still don't understand the working principle of white balance, and there are many misunderstandings in understanding.

It is to realize that the camera image can accurately reflect the color condition of the subject, with manual white balance and automatic white balance.

Many people will encounter such problems when shooting with a digital video camera: the images taken in a fluorescent lamp room will appear green, the scenery taken in an indoor tungsten lamp will appear yellow, and the photos taken in the shadow of the sun will appear blue inexplicably. The reason is the setting of white balance.

Baidu encyclopedia-white balance