What does it mean that computers and darkroom technology are not allowed to change the original picture except tone processing?

It means to ensure the authenticity and objectivity of the image. Apart from tone processing, no computer and darkroom technology can be used to change the original appearance of images. This means that in a photo contest or exhibition, contestants or authors are not allowed to use computers and darkroom technology to modify images except for tone processing, so as to ensure the authenticity and objectivity of images. In order to ensure the authenticity and objectivity of photographic works, it is forbidden to use computers and darkroom technology to change the original images, so as to prevent contestants or authors from tampering with the images through technical means and obtaining improper honors and interests.