1. A method of processing an image, the method comprising: irradiating an object with an ultrasonic wave generated by an ultrasonic probe of an ultrasonic imaging apparatus; generating an acquired image of the object, based on an ultrasonic echo wave reflected from the object and received by the ultrasonic imaging apparatus; estimating a point spread function (PSF) of an acquired image; generating, by the ultrasonic imaging apparatus, a restored image by performing image restoration on the acquired image using the estimated PSF based on a generalized Gaussian model using inverse filter frequency domain, wherein the performing the image restoration comprises: calculating an intermediate result value via inverse filtering in a frequency domain based on a model generated by adding an additional parameter to the generalized Gaussian model, and calculating the additional parameter based on the model generated by adding the additional parameter, wherein the model is configured to produce an optimum solution in response to the additional parameter having a minimum value; and displaying the restored image.