Filters

Main Menu: Image > Filters
Shortcut: Ctrl-Alt-F

There are two kinds of filters, which can be applied on images or selected areas.

1. 3x3 spatial convolution filters

A 3x3 Filter is a set of actions that combines each pixel of an image with the surrounding pixels. Combining is performed through a kernel which is a 3x3 matrix. Pixels inside the kernel are used for calculation for the output image, which usually is located at the center of the kernel.

You can create new filters and save them using the Save button. After all desired values for 3x3 kernel and divisor are entered, try your filter on the current image. If you want to save this filter as an user defined filter, use the Save button.

2. Morphing filters

Morphing filters may be used for removing artifacts or enhancing, dilating or eroding edges from the image. Notice how the straight lines are removed from the above image by using a Closing filter.

Window size determines the filter strength.

Image Navigation controls

If the entire image is not visible in the image  window, you can use the navigation buttons to bring another area of the image into view or to zoom in or out the image.

Click Restore to undo any changes applied to the image.

Only if Auto Apply is selected or if you selected Apply once, changes will be applied to the image, otherwise the will be only previewed.

To apply the changes to the image either click Apply, select Auto Apply or click OK to apply the changes and close the window.

If Auto Apply is selected, the filter will be applied as soon it is selected from the list, but when its values are modified. You should click Apply after you finished adjusting filter values to preview its effect.

If Additive is selected, each new selected filter will be applied on top of previous ones, otherwise the filter will be applied on the original image.