Suppression of ringing artifacts during image resizing

Apparatus for suppressing ringing artifacts during digital resizing of an image, said apparatus comprising a processor operative to:

• calculate a first difference between two inner of four adjacent image samples;
• calculate a second difference between two outer of said four samples;
• correct said first and second differences by inverting the sign of said first and second differences when said first difference is negative;
• triple said first corrected difference;
• compare said second corrected difference with said tripled first corrected difference;
• and
• suppress ringing artifacts between said two inner samples using a linear interpolation model when said second corrected difference is greater than said tripled first corrected difference.

Apparatus for detecting ringing artifacts during digital resizing of an image, said apparatus comprising a processor operative to:

• calculate a first difference between two inner of four adjacent image samples;
• calculate a second difference between two outer of said four samples;
• compare said first difference with zero;
• triple said first difference;
• and
• compare said second difference with said tripled first difference, wherein:
• said ringing artifacts are detected when either said first difference equals zero or said second difference is greater than said tripled first difference.

Apparatus for suppressing ringing artifacts during digital image resizing, said apparatus comprising a processor operative to:

• calculate a difference between two inner of four adjacent image samples;
• set a first gradient equal to said difference;
• set a second gradient equal to said difference;
• and
• suppress ringing artifacts using said first and second gradients to generate a continuous signal model of an image being resized.