A method for heating a preform for blow molding, the method comprising the steps of: providing a preform suitable for blow molding; heating the preform during transport of the preform through a heating system comprising a conveyor, at least one heating means, and a camera, the heating system including an entrance where the preform enters the heating system and an exit where the preform exits the heating system; and measuring, by the camera, the temperature of at least a portion of the preform along its longitudinal axis and around its circumference after transport of the preform past the at least one heating means of the heating system and before the preform is transported to the exit of the heating system; the method characterized by the following steps: compiling the measured temperatures of the at least a portion of the preform; converting the compiled measured temperatures into a three-dimensional thermal image representing the measured temperatures of the at least a portion of the preform; and performing a processing step based on analysis of the three-dimensional thermal image, wherein, when the analysis of the three-dimensional thermal image results in a determination that the preform does not have an acceptable temperature profile, the processing step includes one of: transporting the preform from the exit of the heating system and back to the entrance of the heating system for additional heating by the at least one heating means; or transporting the preform from the exit of the heating system for recycling of the preform when the preform is rejected as unsuitable for blow molding. providing a preform suitable for blow molding; heating the preform during transport of the preform through a heating system comprising a conveyor, at least one heating means, and a camera, the heating system including an entrance where the preform enters the heating system and an exit where the preform exits the heating system; and measuring, by the camera, the temperature of at least a portion of the preform along its longitudinal axis and around its circumference after transport of the preform past the at least one heating means of the heating system and before the preform is transported to the exit of the heating system; the method characterized by the following steps: compiling the measured temperatures of the at least a portion of the preform; converting the compiled measured temperatures into a three-dimensional thermal image representing the measured temperatures of the at least a portion of the preform; and performing a processing step based on analysis of the three-dimensional thermal image, wherein, when the analysis of the three-dimensional thermal image results in a determination that the preform does not have an acceptable temperature profile, the processing step includes one of: transporting the preform from the exit of the heating system and back to the entrance of the heating system for additional heating by the at least one heating means; or transporting the preform from the exit of the heating system for recycling of the preform when the preform is rejected as unsuitable for blow molding. compiling the measured temperatures of the at least a portion of the preform; converting the compiled measured temperatures into a three-dimensional thermal image representing the measured temperatures of the at least a portion of the preform; and performing a processing step based on analysis of the three-dimensional thermal image, wherein, when the analysis of the three-dimensional thermal image results in a determination that the preform does not have an acceptable temperature profile, the processing step includes one of: transporting the preform from the exit of the heating system and back to the entrance of the heating system for additional heating by the at least one heating means; or transporting the preform from the exit of the heating system for recycling of the preform when the preform is rejected as unsuitable for blow molding. transporting the preform from the exit of the heating system and back to the entrance of the heating system for additional heating by the at least one heating means; or transporting the preform from the exit of the heating system for recycling of the preform when the preform is rejected as unsuitable for blow molding.