Linear gradient after lens distortion correction
What problem do you see this solving?
With Leica Q3 and with some other lenses which need distortion correction (as the Sony 20-70) if i create a layer with linear gradient it appears not linear (t'distorted) even if the overlay graphic appears perfectly linear.
The only way to get a true linear gradient is to disable the distortion correction but this is not a solution as the correction is needed .
Note that this does not happens with radial mask which produces correct results even if the overlay graphic appear distorted. (opposite situation but not a problem in real use)
By the way I have checked in adobe ACR (which I don't use) and the liner gradient is perfectly linear even after the distortion correction as it should be
When was the last time you were affected by this lack of functionality, or specific tool?
every time I need a linear gradient and I am using a lens which needs detorsion correction.
Are you using any workarounds or other solutions to achieve your goals in Capture One?
the only work around is to use a brush instead of a gradient but it's not the same thing for two reasons: first it is not so quick and second if I copy and past setting on another file I have to delete the level and make another one every single time.
Are you happy to be contacted further about this suggestion or request?
yes
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In my experience the way to get the linear gradient lines parallel in this situation is to make sure to drag out the gradient from the middle of the edge, not from one side or the other.
Ian
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SFA - the problem is illustrated here. If you drag off centre, the gradient mask may be tapered if there is a lens correction. (You could argue that it is more sensible for the mask to follow the geometry of the uncorrected image, but you can see why users might not like that.) And it was meant to say "non-parallel gradient mask" but some words got lost when I resized it for the forum, I think.
Ian
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Here's a related request: Gradient masks after keystone adjustments.
I asked support about the issue; here's part of the reply I got:
We are aware that there is an issue with the Radial, Gradient masks, and the brush in relation to the image geometry. When using tools such as Keystone or Distortion (lens correction tool), these masks can become deformed as they are tied to the image geometry. We understand that this can be burdensome for our users.
Please note that this issue has been present for some time (from almost the beginning) and changing it would require significant resources as it would involve rebuilding a substantial portion of how Capture One core functions in relation to tools and the image. Consequently, the cost of fixing this issue is quite high.
However, we want to assure you that addressing this issue has always been our intention. We also believe that the impact of this issue is not very significant, as it is only noticeable when pushing Keystone a bit to its limits, which is not a common scenario. Additionally, there is a simple workaround for those who are affected by this issue, which involves applying the mask before applying Keystone.So basically, in the view of Capture One, the company, the issue is insignificant and would cost too much to fix.
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Thank-you Ian but what I ma saying has nothing to do with what you say the problem is different!
As I said the problem is that the linear gradient is distorted independently from how you draw it!
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Can you show a screen shot to show how it is distorted?
Ian
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SFA
In my experience there is a big difference in the behavior of the linear gradient and the radial gradient with files that have been strongly corrected for distortion with the lens profile.
With linear you get the overlay graphic perfectly linear but the resulting gradient is distorted, with the radial gradient you get the opposite situation as the overly graphic is distorted but the effective gradient is correct.
At list this is what I get with the 28mm of the Leica Q3 and with the 20-70 by Sony which are two lenses that need a strong distortion correction.
Best regards
Lorenzo
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There it is!
The first one is a linear gradient on an Leica Q3 with distortion correction activated as you can see the gradient is distorted.
The second one same thing but with the distortion correction disabled and as you can see this time the gradient is linear but unfortunately I like to work with pictures with no distortion!
Best regards
Lorenzo
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OK, I see what you mean. It's curious, because
- if you draw the mask in the middle, as I suggested, the lines are straight and parallel, but nevertheless the mask itself is curved, and
- if you draw the mask away from the middle, you get both things - the lines aren't parallel (but they are straight), and the mask is curved too, but no longer symmetrically.
I'd never noticed the mask being curved like that, though I suppose that in many cases it would make little difference: the mask would have a fairly gradual fall off and in any case a dead straight mask wouldn't always be any better. In my image, I used a gradient mask to lift the shadows in the foreground which are not straight anyway. I'd need a mask with a very gradual fall off so that it didn't look too obvious.
Your mask is very hard edged, though it may be you have done it like that just to make the effect easy to see.
So I agree it's odd. Clearly the mask is following the geometry of the uncorrected image, even though the lines aren't. And it would make more sense for the mask to follow the geometry of the image as corrected. How much of a difference it makes in real use depends on how soft the fall off in the mask is, I presume.
From the reply that Thomas Kyhn had from Support, it sounds like there is a chance that they may do something about it eventually. (His case was about masking with the keystone correction active, but it's all part of the same issue, it seems.) Meanwhile, I suppose
- in many images it won't matter, because you want a pretty soft mask anyway, such as in my image, but
- when it does matter you can try what was suggested to Thomas, and disable the correction while you draw the mask. The trouble with that, though, is that for correction of lens distortions, straight lines in the image may only be straight in the corrected image which is very obvious in the pews in the foreground of your image (do they call them pews in a synagogue?) so drawing the mask as required with the correction off may or may not be any easier.
Ian
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Obviously my example is absolutely exaggerated but the distorted effect of the linear gradient tool is visible even with softer settings.
Obviously if the more the gradient is draw in the middle of the frame the less the distortion effect is visible as the distortion correction is stronger near the edges of the image.
Using the gradient without applying the distortion correction is not an option as specially with some lenses the distortion correction is absolutely needed.
Obviously this problem is visible especially with lenses that need strong distortion correction like the one on the Leica Q3 and also with the 20-70 by Sony and this effect is not a problem with lenses which are physically corrected.
As I said I tried with Adobe ACR (which I don't use) and the linear gradient is perfect after the distortion correction as it should be!
Lorenzo
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I'm not sure about the exact consequences of the distortion correction issue described above, but keystone adjustments don't just affect the shape of gradients. One useful thing when placing gradients is the option to hold down the shift key to ensure that they're vertical/horizontal. This usually doesn't work when keystone adjustments have been applied, and it usually makes no sense to apply gradients before keystone adjustments have been applied, so this workaround isn't of much use.
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I am a very practical person. What i know till now is that in C1 with some lenses (on the q3 I can't change it -))) in some cases linear gradient tool is problematic while it's not on ACR.
To me it seams "normal" that a tool like the linear gradient should operate on the corrected image as it is the first thing you do and also because it's not a choice but I am obligated to do the distortion correction!
I know very well that I can rasterize the mask and then adjust it with a brush and this is what I do already but we must admit that this is not very comfortable especially if you have to deal with hundreds of files!
Will I start working my raw files with ADOBE ACR or LR? Certainly not! I work on C1 since many years and I don't want to change as I am very happy with the results!
I understand that it might be difficult to fix this problem but I am sure that it will be fixed because C1 is a serious software and this behavior does not have any sense!
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I understand that it might be difficult to fix this problem but I am sure that it will be fixed because C1 is a serious software and this behavior does not have any sense!
Unfortunately that isn't always how things work. Capture One has had this issue for many years, the company knows about it, nothing has happened yet, and – as the reply from support cited above indicates – it's unlikely that this will be fixed any time soon. The same goes for many other old issues.
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