Nuke Tips&Tricks l Pixel Color Adjustments

hey guys welcome back to post series I did  a short video on how you can change or how   you can see your pixel values as you're moving  your mouse around and your viewer I want it to   go a little bit further to show you how you  can use those pixel values to grade an image   so I have a setup here where I sampled a color  from this green trees Again by holding down   control while my mouse is inside of the viewer  I went ahead and sampled a pixel for a value   of green that I want to perhaps um I'm going to  grade another part of my image I actually chose   this little building Edge and I want to make this  Edge the same color green that I have here so what   I would do in that case I would take a mental  note of these values here my red green and blue   you can also see the Hue saturation value  and luminance as well but for now we're   going to just focus on these red green and  blue values and we're going to adjust this   grade note so that we can match our building  Edge to this green pixel that we've sampled   now if you want to remove this sample because as  you can see the color will stay here but what we   will need to do since we want to match exactly to  this green we are going to have to sample one of   these pixels because we're going to want to change  this pic the pixel value that we select to match   these values so I oftentimes just go ahead and  write this value down if I'm going to do this   process I'll just write these numbers down so that  I have them and I know what I'm trying to match   to so let's go through that process I actually  already set it up but I'll do it one more time   to show you guys it's a little bit of a process  so if I have this value here where these are   the pixel values I'll go ahead and write them  down like I said so that I can reference them and once I have them written down  we'll go ahead I'll create a new   grade node so you guys can see the  process that I usually use this for   and then we want that one to be our mask I'll just  disconnect this since we aren't going to use it   and now I want to grade this building Edge  now I'm going to draw a new Roto shape too   because I do want to go ahead and show you guys  something so I'm drawing a roto here let's see and I want to see my adjustment and  for this example I'll go ahead and   attached this grade since I already  doubted it and it has some values so let's see how this is looking   now if I disconnect my mask you'll see  that the image turns green so if you're   ever working with a roto and you're wondering why  you aren't seeing even though here in the viewer   this looks totally fine but you're not seeing  the effects of that mask inside of your comp   you might be wondering why not and the reason for  that is usually because the format of the Roto   shape is not matching the format of the plate so  what you would need to do is there's a down arrow   here and we can adjust the format right here in  our Roto node so we would want to make sure our   Roto format is matching that format of the plate  so we would go ahead and change this and now we   immediately see that that image turns green in the  way that we were looking for it to change before   so if you're ever having those problems make  sure your Roto format is matching your plate   and like I said I did go ahead and dial  in this grade and actually so it's it's   a process of let's go through it so um you you  want to I created this new grade so did I okay   so what we want to do is let's see sample one  of these pixels in the area that we're going to   change and again we want to hold down control and  click we sample the pixel we now have these values   here now we want these values to match the values  that we sampled earlier so that's why we wrote   them down because now we don't have any reference  to that value because we have a new value selected   so since we have this now we know that we want to  adjust I'll actually just leave this here we want   to adjust our red green and blue values until  these values are similar to what we had before   so since I wrote them down I'll go  ahead and just my I'll start dialing   my red down I think the value we had  was two three three so we have two   three they just keep adding new digits you  probably need like four two three three five three   so we have a little bit too many there we go so  that was our old red value and now our green value   was 0.3 8. so let's go down till we get to three  eight three three one so let's see can we get that   with two no we probably need another one and maybe  we'll just add another one just to dial it in   three three so we want three did  it go too far okay three three one   and then we might need another one there  we go so we doubt in our red and our green   and now we'll dial in our blue our blue value  was point zero so we have to go way down .06 837 so let's keep going .06 I might just  add another two just to get it in there 0.06 -837 so we want to go up to eight we want  to go down to three and then down to seven   so let's just dial this down to seven so now  we have actually adjusted this grade and and   we adjusted these pixel eyes now all of the pixel  values of course will vary because we only sample   one but overall we can see that we're having  this same green right away and all we had to do   was to make sure that our values were matching so  this is a very good way that I use sometimes when   I'm trying to match a very specific color  I just go ahead sample some pixels that   um you know match the color that I'm trying to  get to and then I dialed in this in this way of   adjusting you know on a like Point like very  specific number basis until I'm getting this   um the exact same values down here and that'll  usually get you close and of course you know   you might need to adjust this if you're looking  for something different but this is a very quick   and easy way to well it's not that quick  but it is a very easy and simple as well   as straightforward way to get colors exactly the  same so that's one good thing about having these   pixel values throughout our shot so that we can  see exactly what colors we don't have to guess   when we're color correcting you know we don't  have to guess or like try to figure out what   how to dial in these adjustments all the time  we could just go ahead and just sample some   pixels use that as our starting point and to get  us somewhere close and then we can go from there

Channel: Post Series: A Nuke course by Shonda Hunt

Views: 993

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Id: TTitZ0r95QQ

Length: 8min 19sec (499 seconds)

Published: Thu Dec 15 2022