Solution
If certain kinds of black stains, dots, or dust are always visible in the same areas on images captured with the camera, dirt or dust may have adhered to the image sensor (CMOS).
Clean the image sensor, prevent dust from appearing in images
When changing the lens on a Digital Single-Lens Reflex Camera or Interchangeable-Lens Compact System Camera, depending on the environment and situation, it is possible for particles and dust in the air to attach to the image sensor.
Because this phenomenon cannot be completely prevented due to structural reasons, the image sensor can be cleaned when you think there might be dust on it.
The camera is equipped with a Self Cleaning Sensor Unit to remove dust from the front side of the image sensor automatically.
IMPORTANT
If the dirt or dust cannot be removed by the means above, please consult a Canon repair center.
Removing dust from images using the software that came with your camera
Digital Photo Professional (EOS software) has a function that you can use to remove unnecessary spots (dust and dirt) in images and blend those areas in with their surroundings. For details, refer to the Digital Photo Professional Instruction Manual.
Digital Photo Professional Instruction Manual can be downloaded from the Canon Web site.