An image generating apparatus includes an obtaining unit configured to obtain plural pieces of tomographic image data, in which each piece of tomographic image data indicates a cross section of substantially the same position of a subject, a calculation unit configured to calculate a motion contrast value based on the plural pieces of tomographic image data and a comparison result of a representative value of the plural pieces of tomographic image data indicating a signal intensity and a threshold, a generation unit configured to generate a motion contrast image of the subject based on the motion contrast value, and a change unit configured to change the threshold.
