I still find that the masking of complex areas in dt is difficult. Using multiple bands certainly helps but without the ability to add and subtract areas images like this one become almost impossible.
I would be interested to see how others attack such problems.
In this image I simply need to overall darken the sky area.
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I tried a couple of approaches…
First, an instance of exposure with a drawn+parametric mask. First a gradient, then parametrically selected only blue-green and a brightness range.
Not very happy with the transitions around the trees, although the mask looks good:
DSCF3968.RAF.xmp (13.0 KB)
Then instead, I tried using a new instance of color calibration, and dropping the blue and green channel brightness, still with a gradient but no other masking:
I think this looks much better…
but the mask rather smothers the smaller branches and the larger that the feathering radius becomes the more the mask covers detail
I do think that you are correct that the second solution work better but it does not solve a general problem with the masking of fragmented areas.
True. Personally, it’s not something I want to do as don’t like editing to that level - much prefer to stick to more global adjustments, but that’s just me.
I think it would be hard to get clean edges to the mask areas too…
Hi David, is there another program that you feel can mask this image better? If there is it might give some ideas for the developers on how to improve masking in DT. The reason I am devoted to DT is I just love the masks that seem so much better than any other program I have experienced, hence my question to you. I know when you make selections in GIMP that you can add, subtract etc and maybe this is what you would like to see with DT’s masks. I am not sure if that would be practical to implement.
While I could not figure out a masking strategy to select the background I did have a degree of success lightening the background using the new color equalizer module.
The alternative would be a drawn mask as in the GIMP, where you can draw at pixel level…
DSCF3968.RAF.xmp (12.5 KB)
In this simple scene i tried another approach without any mask, i only darkened the blu channel in the channel mixer.
Chromatic aberrations don’t help to seamlessly exclude the branches too… 
Hi Terry; The image that I submitted was probably at an extreme … but we do need to address such circumstances every now an then as we edit our images.
The masking in dt is truly extraordinary. No question! It certainly sets this software apart from the commercial alternatives and since ‘dodging and burning’ are so basic to photography it becomes one of the leading reasons for the software’s considerable acceptance.
My background was as a developer of satellite data analysis systems where one of the critical tasks was the differentiation of land-forms that had both hard and soft edges. We worked with 6 band data (not so different to image data sets) but needed to employ an additive and subtractive system.
dt already uses such a system (maybe even more sophisticated in reality) but the dt system does not appear to make it simple when combining or eliminating raster areas. A great pity.
I do not want to go out to Gimp, or other programs, to do my masking, especially as dt’s process is already so strong.
I had hoped that the boost slider might help in the problem, but that appears to be a for a different purpose. It is interesting in B.H.'s fine videos on masking the ‘boost’ was also not used or demonstrated … do others use it I wonder?
Masking is vital in our process and the fact that the mask complex runs through the entire set of dt’s processes is a clear indication tat the developers fully understand its importance. Fine tuning it to better suit fragmented and complex situations in my opinion would be helpful.
I don’t use dt but some editors have a ‘Threshold’ function where all pixels equal to or over a certain value are made white and all below are made black.
Here’s one made in the GIMP:
Good for images with contrast like yours. Some may not like missing twig parts in the above but that’s just where I set the slider real quick. Could have gone high and got to work with a brush but this was just to demonstrate a quick method … does dt have a Threshold function?
HTH
I do find that ‘contrast’ of the mask is important. In the case of this image, pushing a high contrast for the mask does keep the small branches ‘safer’ and permits some greater expansion of the scale … but I still would like to make a secondary selection.
Hi David,
one feature request I made was for the ability to grow or shrink a parametric mask by a defined number of pixels such as 1 or 2 pixels. I do this when making masks from selections in GIMP. It was explained to me that this was technically not possible to achieve.
The image you have provided here is very challenging. I like it for that reason. Besides wanting to create a mask for the mask’s sake what were you hoping to achieve when the mask was created? Possibly my use of the color equalizer module or the use of another module to brighten or darken based upon color channel or shadow and highlights may be the best solution. Masking around trees is challenging at the best of times.
I expect if you kept one pair of the sliders of a parametric mask on the same value in a luma channel it would essentially be that…then you move them all up or down to the point where you get the threshold you want… Moving the right pair together will mask the dark parts below the threshold and moving the left pair instead the reverse…and of course you could invert the channel…
Its not the same but using the opacity slide of the mask …not the module but the mask with contrast and you can shrink and expand it a little or even a lot by changing that opacity slider… it can be a useful bump or pull back a little once you have the mask fairly close
Thanks Todd. I will try that. Do you feel it would be a reasonable feature request to be able to grow or shrink a raster mask made from a parametric mask? Maybe it would be too difficult, of no interest to the developers and would just add noise to the GitHub site so hence my question here.
You would really have to grow the original mask and depending on where the module is in the pipeline it could change if you modify a module before the source point for the mask so it can be hard to keep track of… but there could be a feature where you use say the auto picker for a hue mask and it sets the range and you just want to shrink or expand that a little then some mouse scroll could likely be invoked to spread or contract the mask boundaries out from the center or back in
This would be fantastic if it could be implemented. I don’t know how difficult that would be or if the developers would even be interested.
