within a pb frame then the accumulation of errors can be prevented rounding errors occur during interpolation of intensity values when a value obtained from normal division division whose operation result is a real number is a half u00bd integer 0 5 added to an integer and this result is then rounded up to the next integer in the direction away from zero for instance when dividing by 4 to find an interpolated intensity value is performed the rounding errors for the cases when the residual is 1 and 3 have equal absolute values but different signs consequently the rounding errors caused by these two cases are canceled when the expectation for the rounding errors is calculated in more general words when dividing by a positive integer d u2032 is performed the rounding errors caused by the cases when the residual is t and d u2032 u2212 t are cancelled however when the residual is 2 in other words when the result of normal division is a half integer the rounding error cannot be canceled and leads to accumulated errors to solve this problem a method that allows the usage of two rounding methods can be used the two rounding methods used here are a rounding method that rounds half u00bd integers away from zero 0 and a rounding method that rounds half u00bd integers towards zero 0 by combining the usage of these two rounding methods the rounding errors can be canceled hereafter the rounding method that rounds the result of normal division to the nearest integer and rounds half integer values away from 0 is called u201c positive rounding u201d additionally the rounding method.