Education Technology

Median Smoothing

Activity Overview

Median smoothing, more interesting than your average graph. While most median smoothing questions relate to graphs, this activity focuses on an application embedded in digital image enhancement. Students are supplied with a digital image of an old photograph. The original photograph has deteriorated but can be automatically improved by applying various levels of median smoothing. Check it out! 


The most common application of Median Smoothing is based on graphs. In this activity students are provided with an old grey-scale image that has been partially deteriorated through 'pixel drop out'. Each pixel in an image has an associated number between 0 (black) and 255 (white). If a white pixel appears among a cluster of darker pixels such as: {26, 27, 24, 20, 30, 255, 32} then it can be identified as an outlier and subsequently returned to something that more resembles the surrounding number. The TNS file for this activity already has an image. It is the students job to fix the image, automatically, using median smoothing.


  • Median
  • Smoothing
  • Mean
  • Standard Deviation
  • Outlier
  • Inter Quartile Range