11 Replies Latest reply on May 20, 2010 10:08 AM by the_wine_snob

    Learning to use Levels

    ruzun Level 1

      I shoot a lot of underwater video and often the raw footage looks "murky" and has a greenish tinge that is corrected via Auto Levels.  Is there some easy way to use the Levels effect, rather than auto levels so that you can easily match what Auto Levels is doing with the Levels effect?  I've tried and it's really not that simple for me.  I think I would have to correct the RGB channels first, just by sight on the tiny preview window in the Levels Setting.  Then go to the green channels and monkey around some more via trial and error until I get something that looks OK.

       

      can anyone give me some hints on how one would use levels to remove the cloudiness and green cast that many UW video clips have?  Auto levels often just does this with many clips, which is why I tend to use it a lot.

       

      P.S.

      Can someone from adobe make the AUTO correctors in the adjust section of video effects GPU accelerated!

        • 1. Re: Learning to use Levels
          Valter Vilar Level 2

          Hi ruzun,

           

          The three tools I use the most are levels, three way colour corrector and the luma curve in Premiere. You can balance a colour cast, by adding more of the opposite colour to your picture, or video. The Three way colour corrector is great for that. However, you need to find good tutorials on the subject. Color correction is highly subjective and there is no easy answer. It depends a lot on your likes and dislikes. I prefer colder (blue) images more than warmer ones.

           

          What I wish the auto levels did was to show us what its current settings are and then I would go from there but alas that's not the way the stupid thing works. I've never used it because it causes some psychodelic kind of effect (even when temporal smoothing is being used).

          • 2. Re: Learning to use Levels
            ruzun Level 1

            You know that would be the most useful thing in the world.  If you could freeze the clip at a point in the timeline, then the Auto correctors would SHOW you at that point what settings they are using so you could use them for the non-auto version of the correction.  Like if Auto levels would SHOW you at any point what it's current settings are, and you could just use those to set LEVELS yourself, if it varied you could create several points in the clip and change the levels accordingly.

             

             

            I think I will file that as a feature request, perhaps others could as well.  That would really be useful.

             

             

            On some clips AUTO levels does act oddly, but on many clips it behaves just fine and does a fantastic job.

            • 3. Re: Learning to use Levels
              the_wine_snob Level 9

              My normal workflow is to add Levels (and adjust on my reference monitor), add Shadow & Highlight (Auto Mode unchecked, i.e. OFF), then 3-Way (or Fast) Color Corrector. Usually, I will then go back up to Levels and maybe S&H to do fine-tuning.

               

              I works less with numbers, and more with my eyes and the reference monitor.

               

              There are probably almost as many ways to do this, as there are users out there, and the particular source footage might dictate that I change my workflow to suit that.

               

              Good luck,

               

              Hunt

              • 5. Re: Learning to use Levels
                shooternz Level 6
                Like if Auto levels would SHOW you at any point what it's current settings are, and you could just use those to set LEVELS yourself, if it varied you could create several points in the clip and change the levels accordingly.

                 

                 

                Use the Waveform monitor as the tool to check levels..

                • 6. Re: Learning to use Levels
                  ruzun Level 1

                  Using the RGB parade mode of the waveform monitor does help a lot, thank you for the suggestion.  It's still very time consuming and tedious but it may help me learn how to use levels manually, and over time I may get faster.  I still would like to be able to see the numbers used by AUTO levels, but by using RGB Parade mode in the waveform monitor I can examine the RGB channels when AUTO levels is active, then toggle auto levels off and toggle LEVELS back on, play with the in/out and gamma settings for one color to get it to match what Auto had, then toggle auto back on and look at the next color, toggle auto levels off and levels back on and set the second color to match etc.

                   

                   

                  RGB Parade waveform monitor IS a great learning tool for levels, thanks so much for the suggestion, but at this point its REALLY slow and tedious to get them to match up.  I think over time as I get more of an intuitive feel for this it will get faster.

                   

                  -Roger Uzun

                  • 7. Re: Learning to use Levels
                    shooternz Level 6

                    Might be slow but apart from using the "eye"...every professional Color

                    Grader / Colorist uses the scopes.

                     

                    Little tip for you: Always set your LEVELS first before doing any color corrections.

                    • 8. Re: Learning to use Levels
                      ruzun Level 1

                      It's slow for me now because I have no feel for it.  I have to turn off LEVELS, turn on AUTO LEVELS examine the graph, toggle auto levels OFF and levels back on, try and make the red portion of levels match what I saw for auto levels, rinse, repeat, rinse, repeat until all 3 colors look the same in LEVELS and AUTO levels on the RGB graph.

                       

                      Once I get more of a feel for what each setting in levels does, I think it will get faster for me and I won't need to rely on the graph so much.

                      • 9. Re: Learning to use Levels
                        shooternz Level 6

                        Dont use Auto Levels.

                         

                        Train your eye and your technique instead.  Its a craft not a process.

                        • 10. Re: Learning to use Levels
                          joshtownsend Level 2

                          Here's a level's reference chart that should help you understand whats going on better. http://www.motionworks.com.au/2007/01/levels_guide/

                           

                          Look at your RGB Parade in a reference monitor and watch what happens when you adjust 'em. Also mainly just adjust the input. The Output can really mush things up if used wrong.

                           

                          Basically the adjustment on the left (when pulled right) pushes the picture into the shadows. Higher in the graph.

                           

                          The one on the far right (when pulled left) pushes the picture into the highlights. Lower on the graph.

                           

                          The middle, your gamma, shifts the middle or mids of the picture.

                           

                          Also notices it doesn't shift the colors is pushes them. Hope this 'll start you in the right direction. Once you learn it and can go beyond just AUTO coloring and make your video looks way better.

                          • 11. Re: Learning to use Levels
                            the_wine_snob Level 9

                            Nice link Josh.

                             

                            Thanks for posting it.

                             

                            Hunt