One of the underutilized (an mysterious) feature of Rainmeter is the ColorMatrix's ability to modify images.
kenz0 created an excellent tip for it's use, but I wanted to have a simple way to "play" with the values and see the effects.
So I created a "playground" that makes it easier to see the effects the matrix settings have on images.
Double-click the left image to open your Picture folder.
Drag and drop an image into the upper portion of the skin (either image).
Now either click one of the 'buttons' presets on the lower right, or modify the values in the table to see the matrix effects. Once you have a ColorMatrix you want to apply to an image, you can save it to your clipboard with a double-click of the transformed image. Paste that code into your image meter to apply the effect. Have fun! E.T.