Lab Contents

Visual Comparison of Mean and Median Filters on a noisy Image

The filters and other image processing operations work on either the entire image or the active selection. Filtering only a part of an image allows comparison of different filters.

• File -> Open... menu, select Sample Images / MAS Journal article / SRM484.tiff

This is a magnification standard - the distance between the lines is what is of interest.

• Click on the rectangle selection tool and select the middle third of the image

• Smooth this middle strip using the Process -> Smooth menu, option key held down.
• I'm not sure of the key to use on the PC. If the key modified menu is not available, just use the smooth without the option key, or use some other filter. (Option key is not active in ImageJ.)
• Select the right third of the image, and use the Median filter - Process -> Rank filters... menu, 10 iterations. Use Process / Filters / Median, and a radius of 2 pixels.
• Enhance the contrast with the process -> equalize menu. Process / Enhance Contrast, click on the equalized histogram box.

Details of the original and the two filteres can now be compared visually.