For more crude / unclamped versions of some merging operations (including
"overlay"), you can also use the olde "Merge" node (as opposed to the
default "Merge2".
Merge {
inputs 2
operation overlay
name Merge1
selected true
xpos -254
ypos 199
}
On Wed, Jan 28, 2015 at 8:34 AM, Mads Hagbarth Lund <madshl...@gmail.com>
wrote:
> It's just bad with the overlay thing, as it is a pretty useful way to add
> grain and do dodge/burn effects. It works out of the box in Photoshop,
> Fusion and AfterEffects but you have to make your own overlay gizmo to make
> it work in Nuke.
>
>
> Den 28/01/2015 kl. 17.11 skrev Daniel Short <danisnotsh...@gmail.com>:
>
> I wondered how the screen would need to be calculated differently since
> the invert function might get you some crazy values in float space.
> It makes sense that they changed it to give us a visually accurate result
> when a mathematical one would look like an error.
>
> On Wed, Jan 28, 2015 at 10:49 AM, John Mangia <j...@johnmangia.com> wrote:
>
>> Looks like the nuke screen algorithm has a low pass to allow for values
>> over 1 to comp more naturally. You can see the difference if you expose
>> down.
>>
>> On Wed, Jan 28, 2015 at 10:37 AM, Mads Lund <madshl...@gmail.com> wrote:
>>
>>> Ahh ok, so the "Screen" operation in the merge node does not just screen.
>>>
>>> Screen is the same as the Merge
>>> <http://help.thefoundry.co.uk/nuke/9.0/content/reference_guide/merge_nodes/merge.html>
>>> node,
>>> only with operation set to screen by default. It layers images together
>>> using the screen compositing algorithm: A+B-AB if A or B ≤1, otherwise
>>> max(A,B). In other words, If A or B is less than or equal to 1, the
>>> screen algorithm is used, otherwise max is chosen. Screen resembles plus.
>>> It can be useful for combining mattes and adding laser beams.
>>>
>>> However i still don't see why they don't apply this to the overlay
>>> method aswell. (why would you want clamp the image?)
>>> And it also doesnt explain why it clamps at 0 (since multiply does not
>>> clamp at 0)
>>>
>>>
>>>
>>> On Wed, Jan 28, 2015 at 2:46 PM, John Mangia <j...@johnmangia.com>
>>> wrote:
>>>
>>>> Screen is also a multiplicative operation, it's just inverted images
>>>> multiplied together and re-inverted.
>>>>
>>>>
>>>> On Wed, Jan 28, 2015 at 8:35 AM, Ron Ganbar <ron...@gmail.com> wrote:
>>>>
>>>>> The math used in Nuke for Screen makes it inheritingly clamp (it
>>>>> doesn't really clamp, but can not produce colors brighter than 1).
>>>>>
>>>>>
>>>>>
>>>>> Ron Ganbar
>>>>> email: ron...@gmail.com
>>>>> tel: +44 (0)7968 007 309 [UK]
>>>>> +972 (0)54 255 9765 [Israel]
>>>>> url: http://ronganbar.wordpress.com/
>>>>>
>>>>> On Wed, Jan 28, 2015 at 2:15 PM, Mads Lund <madshl...@gmail.com>
>>>>> wrote:
>>>>>
>>>>>> According to the documentation:
>>>>>>
>>>>>> • overlay - Image A brightens image B.
>>>>>> Algorithm: multiply if B<.5, screen if B>.5
>>>>>>
>>>>>> However Nuke also clamps the colors between 0 and 1.
>>>>>> It seem that all other compositing software does not clamp between 0
>>>>>> and 1, so i am wondering if this is a bug in Nuke?
>>>>>>
>>>>>>
>>>>>> _______________________________________________
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>>>>>> http://support.thefoundry.co.uk/cgi-bin/mailman/listinfo/nuke-users
>>>>>>
>>>>>
>>>>>
>>>>> _______________________________________________
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>>>>>
>>>>
>>>>
>>>>
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>>>
>>>
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>>
>>
>>
>> --
>> John Mangia
>>
>> 908.616.1796
>> j...@johnmangia.com
>>
>> _______________________________________________
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>
>
>
> --
> Daniel Short
> www.danisnotshort.com <http://www.vimeo.com/danisnotshort>
> 215.859.3220
>
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>
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