INTERPOLATION RECORDING SYSTEM

PURPOSE:To attain high picture quality recording for a pseudo intermediate tone picture by comparing data of upper and lower lines of an interpolation line, detecting an area different from a data and setting a virtual border line in the area. CONSTITUTION:The virtual border line is set at a point changing in the main scanning direction of the data of upper or lower the interpolation line in the area where the data of upper and lower line of the interpolation line differs. For example, the data of n-th and (n+2)th lines are arranged shown in figure and when inversion of data takes place in the n-th or (n+2)th lines in the dissident area, it is takes as the virtual border. When the data of horizontal picture element data adjacent to the dissident area belongs to the same category, a virtual border is provided in the middle of the dissident area. Thus, the picture with mixed black/white area of the pseudo intermediate tone expression is interpolated with high picture quality.