Method of determining the extent of blocking artifacts in a digital image

A computer program product for determining the extent of blocking artifacts in a digital image comprising:

• a computer readable storage medium having a computer program stored thereon for performing the steps of:
• a) forming a column difference image from the difference between columns in the digital image;
• b) averaging the values in the columns in the column difference image to produce a column difference array;
• c) computing the average of the values in the column difference array that are separated by one block width to produce a block averaged column difference array;
• d) locating a peak value in the block averaged column difference array;
• e) calculating a mean value of the block averaged column difference array excluding the peak value to produce a column base value;
• f) computing the ratio between the peak value and the column base value to produce a column ratio;
• g) repeating steps a)-f) in the row direction to produce a row ratio;
• and;
• h) employing the column and row ratios as a measure of the extent of blocking artifacts in the digital image.