Image data processing apparatus

An image data processing apparatus comprising:

• first means for detecting luminance levels represented by a predetermined number of pieces of a first digital signal representative of an original picture, the pieces of the first digital signal indicating periodically-updated neighboring pixels including a periodically-updated pixel of interest in the original picture;
• second means for calculating differences among the luminance levels detected by the first means;
• third means for deciding whether or not an absolute value of each of the differences calculated by the second means exceeds a predetermined threshold value;
• fourth means for determining whether or not the pixel of interest corresponds to an isolated point in the original picture in response to a result of the deciding by the third means;
• fifth means for setting a luminance level represented by a piece in question of a second digital signal representative of a conversion-result picture in accordance with the luminance level represented by the piece of the first digital signal which indicates the pixel of interest without interpolation when the fourth means determines that the pixel of interest corresponds to an isolated point in the original picture, the piece in question of the second digital signal indicating a pixel in the conversion-result picture which corresponds to the pixel of interest in the original picture;
• and
• sixth means for setting the luminance level represented by the piece in question of the second digital signal according to interpolation responsive to luminance levels represented by neighboring pieces of the first digital signal when the fourth means determines that the pixel of interest does not corresponds to an isolated point in the original picture.