1 With the image you want to work with loaded, open a new view zoomed in on an area of the part you want to mask. In the Actions palette, switch the drawing mode from Colour to Mask. Switch from Paint to Geometry, and select the icon for Open Bézier Spline. Click on your image to set the first point, and continue. Click to create straight lines; click and drag for a Bézier curve.
2 Continue placing the points of your spline along the edge of the area you want to mask. Don’t worry if they aren’t entirely accurate as you can edit them later. When you’ve enclosed the object, right-click the mouse and select Complete to finish the curve. Now you can move individual points. When you’re happy, right-click again and select Render to create the mask.
3 If your mask hides the portion you want to keep, click the Invert User Mask button in the Layers palette. Next, load an image as a background by selecting Load To Layer from the File menu. In the Load to Layer dialog that appears, switch both Fit To Layer and Ignore Aspect Ratio on – this will make the new image fit the dimensions of your masked one.
4 The new background image is loaded into a completely new layer, which appears on top of your masked image. To change the order in which the layers appear, simply pick up the background layer with the mouse, then drop it on top of the masked image layer – this simply swaps the order of appearance, moving the background to the back.
5 Since we don’t need the entire image, we’re going to crop it. In the Actions palette, switch back from Mask to Colour, and switch from Geometry to Canvas. Click the Define Crop button, then drag the mouse over the area of the image you want to keep, releasing it when you’re happy. The main image won’t change, but a new window will appear showing the crop area.
6 Satori doesn’t actually crop the image until you come to export it as a normal bitmapped file. Select Save As... from the File menu, and switch from CVS to a bitmap type such as JPG. In the dialog that appears, make sure you select Use Crop Area in the Output Parameters section, and your finished image will be exported with smoothly blended edges and all cropping intact.