Inverting a luminosity mask
When I try to invert a luminosity mask, I don’t get the results I expect unless I manually play around with the window / level sliders as well. Wouldn’t it make sense for the invert button to invert those values for me too?
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Official comment
Hey guys,
Sorry for the confusion, but inverting a luminosity mask will not behave the same way as inverting a mask that has been created with the masking brush or masking bug. If you have made a change to mask with the masking bug or brush and invert the mask, the effect will be applied to areas where the mask was previously omitting this effect. When creating and changing masks manually (with the masking brush or bug) it does not matter what information exist in your image. The placement of the bug and your brush strokes determine exactly where you want the effect to be applied.
When working with luminosity masks, the Window and Levels sliders will determine where you want the effect to be applied based on the information that exists in the image you are working on. These sliders will remain unchanged when inverting the mask, therefore reading information in the photo and creating the mask based on different areas the image. These sliders may need to be adjusted again after inverting the luminosity mask. We do not recommend inverting Luminosity masks since you are able to adjust the Window and Levels sliders to the proper settings on the first go. If you want the effect to be applied to different areas of the image we recommend re-adjusting the Levels and Windows sliders again or creating a new mask on another filter in your filter stack.
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I find the luminosity mask tricky too. Try inverting it immediately before making any adjustments to it. It might work better for you.
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Doesn’t help if I’m copying the mask and then inverting it though. I would have expected the window sliders to be inverted too as those are what fine tune the mask to get it the way you want it.
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I agree. I find also that inverting a Luminosity mask often gives you a different mask than you'd expect.
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I don't copy luminosity masks but rather just create new.
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Thanks for the response James, so you’re saying it isn’t programmatically possible to flip the windows and levels sliders when you invert a luminosity mask? When I inverted a luminosity mask, it seemed to me as if the sliders’ positions in the Windows and Levels bars had, in effect, to be mirrored around their mid point to get the effect I wanted.
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In response to James comment above, it explains why invert doesn't work the way we expect it to, but It also shows the need for a way to copy a 'flattened' version of the mask, that is, just the binary output without the settings involved. That way we would be able to copy and invert it the way we expected it to work.
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Rick, being an old IT techie, I can’t help but think there’s a programmatic solution. If I’m right in assuming, for simplicity’s sake, that the luminosity mask is an array of pixels each with a level of greyness from 0 to 255, then inverting is subtracting those values from 255 so to speak. Same with the sliders - if the three slider positions are set at individual values, why doesn’t applying the same formula apply? That’s sort of what I was trying to say above - a lot of formulae have an inverse, and i presumed, perhaps naively, that this would be the case for the Windows and levels sliders for luminosity masks so that inversion would give us the visual result we’d expect from a greyscale mask. But obviously the ON1 developers have greater insight into this...
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Pete, I agree and it's what I expected to happen too. Clearly whatever algorithm On1 is using doesn't understand 'invert' the way we do. I don't actually need the lumimosity mask to be recalculated to give me an inversion, I can see a mask result right in front of me and I just want the inverse of it.
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I think I created a wishlist entry, that you can vote for to be able to 'flatten'the luminosity mask and invert it after that. It would be awesome if we could in general treat masks as images after we fine tune the sliders.
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I have an wish list entry for creating luminosity masks based on the current image instead of the original image. I would love to see that voted up as well.
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