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.
For more information, refer to the Related information below.
IMPORTANT
The image sensor is extremely delicate. If the sensor needs to be cleaned directly, having it done by a Canon Service Center is recommended.
Removing dust from images using the EOS software
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.