An image processing program that causes a computer to execute a process, the process comprising: extracting a plurality of consecutive pixels corresponding to one of a first part or a second part of a body, from a pixel column in a predetermined direction of an image of the body, wherein each pixel of the plurality of consecutive pixels has an associated computerized tomography, CT, value, and the image of the body is a CT image; obtaining a statistical value of pixel values of the plurality of consecutive pixels, wherein the statistical value is an average value, a median value, or a mode value of the CT values of the plurality of pixels; and identifying a part corresponding to the plurality of consecutive pixels, among the first part or the second part, based on the statistical value, wherein the identifying of the part includes identifying the part corresponding to the plurality of consecutive pixels, based on a comparison result between the statistical value and a first threshold, wherein the extracting of the plurality of consecutive pixels includes extracting the plurality of consecutive pixels based on a comparison result between a second threshold and a pixel value of each of a plurality of pixels included in the pixel column in the predetermined direction, wherein the first part is a lung field and the second part is a part other than the lung field, and wherein the process further includes: by using a computed tomography image of each of a plurality of slices of the body as the image of the body and using each of a plurality of pixel columns in the computed tomography image as the pixel column in the predetermined direction, identifying a position of a pixel column including pixels corresponding to the lung field among the plurality of pixel columns by identifying the part corresponding to the plurality of consecutive pixels, generating a coronal image of the lung field, using only the CT values of the pixels corresponding to the lung field and based on the position of the pixel column including the pixels corresponding to the lung field, the position being identified in the computed tomography image of each of the plurality of slices, and identifying an upper end and a lower end of the lung field by using the coronal image. extracting a plurality of consecutive pixels corresponding to one of a first part or a second part of a body, from a pixel column in a predetermined direction of an image of the body, wherein each pixel of the plurality of consecutive pixels has an associated computerized tomography, CT, value, and the image of the body is a CT image; obtaining a statistical value of pixel values of the plurality of consecutive pixels, wherein the statistical value is an average value, a median value, or a mode value of the CT values of the plurality of pixels; and identifying a part corresponding to the plurality of consecutive pixels, among the first part or the second part, based on the statistical value, wherein the identifying of the part includes identifying the part corresponding to the plurality of consecutive pixels, based on a comparison result between the statistical value and a first threshold, wherein the extracting of the plurality of consecutive pixels includes extracting the plurality of consecutive pixels based on a comparison result between a second threshold and a pixel value of each of a plurality of pixels included in the pixel column in the predetermined direction, wherein the first part is a lung field and the second part is a part other than the lung field, and wherein the process further includes: by using a computed tomography image of each of a plurality of slices of the body as the image of the body and using each of a plurality of pixel columns in the computed tomography image as the pixel column in the predetermined direction, identifying a position of a pixel column including pixels corresponding to the lung field among the plurality of pixel columns by identifying the part corresponding to the plurality of consecutive pixels, generating a coronal image of the lung field, using only the CT values of the pixels corresponding to the lung field and based on the position of the pixel column including the pixels corresponding to the lung field, the position being identified in the computed tomography image of each of the plurality of slices, and identifying an upper end and a lower end of the lung field by using the coronal image. by using a computed tomography image of each of a plurality of slices of the body as the image of the body and using each of a plurality of pixel columns in the computed tomography image as the pixel column in the predetermined direction, identifying a position of a pixel column including pixels corresponding to the lung field among the plurality of pixel columns by identifying the part corresponding to the plurality of consecutive pixels, generating a coronal image of the lung field, using only the CT values of the pixels corresponding to the lung field and based on the position of the pixel column including the pixels corresponding to the lung field, the position being identified in the computed tomography image of each of the plurality of slices, and identifying an upper end and a lower end of the lung field by using the coronal image.