An image forming system and methods are disclosed. The methods include detecting an ambient temperature of an image forming system by a first thermal sense resistor disposed in a first printhead to obtain a first detected ambient temperature, detecting the ambient temperature of the image forming system by a second thermal sense resistor disposed in a second printhead to obtain a second detected ambient temperature, and determining a temperature difference between the first detected ambient temperature and the second detected ambient temperature of the image forming system by a temperature variation module.