The Cubismplug-in modifies the image so that it appears to be constructed of small squares of semitransparent tissue paper.
This selection box determines whether the background color displayed in the Toolbox should be used when applying the filter. If it is not checked, black will be used instead.
This variable determines the size, in pixels, of the squares to be used. This is, in effect, the size of the little squares of tissue paper used in generating the new image. The slider can be used, the exact pixel size can be entered into the text box, or the arrow buttons can be used.
This variable specifies how intense the color of the squares should be. This affects the opacity of the squares. A high value will render the squares very intensely and does not allow lower squares to show through. A lower value allows the lower squares to be more visible through the higher ones and causes more blending in the colors. If this is set to 0 and Use Background Color is not checked, the entire layer will be rendered black. If it is checked and the value here is zero, the background color will fill the entire layer.
If you are using this to generate background images for web pages and the like, work with a small range of colors painted randomly on a small square. Then apply the Cubism filter with the desired settings. As a last step, try Filters Map Make Seamless to adjust the image so it will tile seamlessly in your background.