Abstract: In effecting error modification of component video data having predetermined relationships, for example in the playback side of a digital VTR for the Y, C.sub.R, and C.sub.B component system, a range of values that is allowable for the data indicated to be erroneous by its error flag, is defined on the basis of the data indicated to be correct by its error flag, and, when the erroneous data is outside the allowable range, such erroneous data is modified to have a value within the allowable range, for example, near the center thereof, and is then output. By this arrangement, when the Y, C.sub.R, and C.sub.B signals are converted into playback R, G, and B signals, the latter do not exceed the ranges of values thereof necessary for proper color balance of the reproduced picture.