This demo shows a 1920x1200 large jpeg displayed in a small FabricImage object. The image starts with a scaling of 0.2 and you can use the corner to increase or decrease the scale. While changing the scale you can observe the lower canvases that offer a detailed view of the image scaling with and without the lanczos filter.
Right click on the image object to change the magnified point in the canvases below.
On the right of the canvases you can see the number and values of the taps used for the filter. The more you shrink the image, the more taps, the more performance hit but also the smoother scaling.
This filter affects performace, you may consider it if your application is exporting small png or jpegs but is using large images.