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.