Method of processing a multi-energy depth overlapping X-ray image, the method being carried out by a processing device and comprising: acquiring, in a predetermined time interval, a plurality of projection target images for each of at least two energy bands formed by a multi-energy X-ray passing through a target where a contrast agent is applied, from a multi-energy X-ray source; and performing an image signal processing on the plurality of target images. wherein performing the image signal processing on the plurality of target images includes: - processing an image from the plurality of target images for at least one of plural predetermined times within the predetermined time interval and for each energy band of the multi-energy X-ray irradiated from the multi-energy X-ray source; - generating, for each of at least one material, a material decomposition image from the target images, with the at least one material at least including the contrast agent, wherein the material decomposition images are selectively decomposed from the detected X-rays that have passed through the target; - estimating respective initial images for each of plural materials, using the plurality of images; - acquiring respective material decomposition images for each of the plural materials from the respective initial images, - determining a correction value for minimizing a predetermined cost function, and - updating an initial image for one of the plural materials, of the respective initial images, to a material decomposition image based on predetermined material decomposition algorithm by applying the determined correction value to the initial image; - measuring the amount of the contrast agent applied to the target by analyzing the generated material decomposition images; - performing a dynamics analysis of the measured amount of the contrast agent within the predetermined time interval. acquiring, in a predetermined time interval, a plurality of projection target images for each of at least two energy bands formed by a multi-energy X-ray passing through a target where a contrast agent is applied, from a multi-energy X-ray source; and performing an image signal processing on the plurality of target images. wherein performing the image signal processing on the plurality of target images includes: - processing an image from the plurality of target images for at least one of plural predetermined times within the predetermined time interval and for each energy band of the multi-energy X-ray irradiated from the multi-energy X-ray source; - generating, for each of at least one material, a material decomposition image from the target images, with the at least one material at least including the contrast agent, wherein the material decomposition images are selectively decomposed from the detected X-rays that have passed through the target; - estimating respective initial images for each of plural materials, using the plurality of images; - acquiring respective material decomposition images for each of the plural materials from the respective initial images, - determining a correction value for minimizing a predetermined cost function, and - updating an initial image for one of the plural materials, of the respective initial images, to a material decomposition image based on predetermined material decomposition algorithm by applying the determined correction value to the initial image; - measuring the amount of the contrast agent applied to the target by analyzing the generated material decomposition images; - performing a dynamics analysis of the measured amount of the contrast agent within the predetermined time interval. - processing an image from the plurality of target images for at least one of plural predetermined times within the predetermined time interval and for each energy band of the multi-energy X-ray irradiated from the multi-energy X-ray source; - generating, for each of at least one material, a material decomposition image from the target images, with the at least one material at least including the contrast agent, wherein the material decomposition images are selectively decomposed from the detected X-rays that have passed through the target; - estimating respective initial images for each of plural materials, using the plurality of images; - acquiring respective material decomposition images for each of the plural materials from the respective initial images, - determining a correction value for minimizing a predetermined cost function, and - updating an initial image for one of the plural materials, of the respective initial images, to a material decomposition image based on predetermined material decomposition algorithm by applying the determined correction value to the initial image; - measuring the amount of the contrast agent applied to the target by analyzing the generated material decomposition images; - performing a dynamics analysis of the measured amount of the contrast agent within the predetermined time interval.