03 Zero opacity point
But I can fix that using opacity control points – there are buttons for these underneath the tool options. To remove the effect I need a zero, or ‘minus’ opacity point, so I click the button (I’ve highlighted this in red), then I clicked on the boat’s cockpit. This adds a ‘minus’ control point, which removes the filter effect in that area. It’s made a visible difference already.
04 Changing the control point size
At the moment, though, the control point operates over a fairly small area, so that much of the boat is still being darkened by the filter. The obvious solution might seem to be to drag the control point’s handle to make it larger. But although the control point is selective, it will still affect similar-toned areas to some degree. If I make this control point larger, it does include more of the boat, but it starts to lighten the sky too much above it.
05 Add more control points
The solution is to stick to the original control point size, but simply add more of them wherever they’re needed. It might sound like a crazy kind of scattergun approach, but it only takes a few extra mouseclicks and it’s really effective. Here, you can see I’ve added half a dozen in the top part of the boat, and it’s now shielded from the graduated filter effect much more effectively. In fact this is exactly how these control points are meant to be used.