1. A video quality assessing apparatus comprising: an alignment information generating part to receive an undeteriorated reference video signal and a deteriorated video signal produced from the reference video signal and generate alignment information related to a temporal deviation between a reference video frame from the reference video signal and a deteriorated video frame from the deteriorated video signal and a spatial deviation between the reference and deteriorated video frames; a spatial feature value calculating part to eliminate the spatial and temporal deviations according to the alignment information and calculate spatial feature values of the reference and deteriorated video frames according to spatial information indicative of video states of the reference and deteriorated video frames; a temporal feature value calculating part to eliminate the spatial and temporal deviations according to the alignment information and calculate temporal feature values of the reference and deteriorated video frames according to temporal information indicative of frame-to-frame video changes of the reference and deteriorated video frames; a subjective quality estimating part to estimate a subjective quality of the deteriorated video signal according to the spatial and temporal feature values; a correction information storing part to store correction information that corresponds to the spatial and temporal feature values and is used to correct the subjective quality; and a subjective quality correcting part to receive the spatial and temporal feature values of the reference video signal, retrieve correction information corresponding to the received spatial and temporal feature values from the correction information storing part, and correct the estimated subjective quality according to the retrieved correction information.