It surprised me when I went hunting for a vignetting-correction filter, and found none. Not having looked for that filter in Photoline all this time I never knew that this common photo correction-filter was missing from all the other amazing things that Photoline can do.
I used or tried various work-arounds. Like making a curves working-layer, setting it so it would over-correct for the corners light-falloff, then flooding it with a circular gradient to vary its intensity across the image, and other things like that. But I was never quite pleased with the results and it was really touchy to try to get the mask-gradient correct as well as matching it up with the amount of over-correction needed by the working-layer's properties itself.
Then I though about using the "Lights" filter in the Effects menu. This is almost exactly what I needed to fix this off-axis vignetting. But I couldn't change end-colors of the gradient used to create the amount of light correction needed. You can only have a white or colored light, and a dark end-point, the perimeter of the fake-light effect.
This tool could be really useful as a vignetting correction tool, especially for the asymmetric vignetting that I found in that photo tonight.
1. It would only need to allow for picking the center and edge colors so I could switch black for white on either end. It could also help with odd color vignetting that can sometimes happen with IR photography and specialty camera-filters if it allowed changing the end-points of the gradient to any colors. There's an odd case with the expensive Leica M8 camera too where they didn't filter the CCD properly and all those cameras suffer from a strange green vignetting when used with certain lenses. A tool with this feature could even repair the photos from those cameras.
2. It would also be very helpful to set an intensity curve to the gradient. So that you could make the gradient stronger at one end or the other. This would allow you to adjust for a rapid light-falloff or a mild one affecting only a small margin in the corners of a photo.
Could these 2 additions be put into the Light Effects filter? It would really benefit photographers, to use an English phrase: killing lots of birds with 2 stones.
In the meantime I had to resort to using a plugin that doesn't allow me to set where the center of the vignetting correction should be, so I couldn't exactly fix the image with its asymmetric vignetting. With the Lights Effect tool with the 2 requested additions, then I could fix a photo like that properly, better than any plugin or other vignetting-correction tool I have ever used in the past.
Now watch, someone's going to tell me ... "The vignetting correction tool with all the features you needed is on menu .... and it's always been there."
Doable, but most editors these days include a nice vignetting correction tool dedicated to the process. One filter or adjustment layer with a couple sliders. Click, slide, slide, and you're done. In Photoline's case though, that "Lights" filter could gain so much more uses if modified to allow for vignetting correction too, as opposed to one for vignetting-correction only. Imagine a stage-lit scene with various colored floods that are really destroying some flesh-tones badly, then your lens adds in its own vignetting too. The "Lights" effect filter could tweak all of them.