To subtract camera noise from an image, one can take multiple dark images with the shutter closed to calculate the average dark signal and its standard deviation, which estimates the noise. While noise cannot be directly subtracted, consistent unwanted signals like bias levels and accumulated dark current can be removed. The process of measuring and subtracting may introduce additional noise, but proper dark subtraction minimizes this effect. For noise reduction, capturing and averaging a large number of images is recommended. Software like MATLAB can be used to automate the averaging and standard deviation calculations, with sample code provided for implementation.