According to one embodiment, a medical image processing apparatus includes an image acquisition part and a data processing part. The image acquisition part is configured to obtain X-ray image data of an object including not less than three phantoms whose X-ray absorption factors are different from each other. The data processing part is configured to generate corrected X-ray image data of the object by correcting the obtained X-ray image data or other X-ray image data. The obtained X-ray image data or the other X-ray image data are corrected using a nonlinear function obtained based on pixel values of the obtained X-ray image data. The pixel values correspond to the phantoms.