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xlistax52479645
Participating Frequently
March 4, 2020
Beantwortet

"Screen Balance" in Keylight(1.2)

  • March 4, 2020
  • 2 Antworten
  • 6580 Ansichten

Hi. I asked for help and got an answer about Keylight(1.2) settings. 

But i realy don't undestand, how "Screen Balance" work. 

In doc from Foundary for AE, "Screen Balance":

------------------------------------------------------------------------ 

Saturation is measured by comparing the intensity of the
primary component against a weighted average of the two
other components. This is where the Screen Balance control
comes in. A balance of 100% means that the saturation will
be measured against the smallest of the other two
components in the screen colour.

 

A balance of 0% means that the saturation will be measured
against the larger of the other two components. A balance of
50% will measure the saturation from the average of the
other two components.

-------------------------------------------------------------------------

 

Keyer look at the saturation on screen color and compare with the same or above saturation and make full transparent screen.

But what "Screen Balance" does?

If i have a green background and "Screen Color" sample as the same color(Green - 240, Red - 50, Blue -20).

and i tweak "Screen Balance" parametr to 0.

The value of saturation screen color will be compared with larger value. In this case with "Red" - 50. Becouse Green more intensive then Red it's do not any affect on the pixel. Pixel are full transperent.

----

But, when the "Screen  Color" = Green - 240, Red -240 or above, Blue - 50.

The value of saturation screen color will be compared with larger value. In this case with "Red - 240 or above"

Becouse Green is less intensive(or equvivalent) then Red it's must make opacity pixel, BUT we set "Screen Balance" to 0 and...... What this compare it does?  In both cases pixel are transparent. Why i must compare this 2 other value? I must compare Green with less or more Green. I don't understand. What sense in this comparison when green value alwayse greater? Please, help!

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Beste Antwort von Mylenium

Screen balance is pretty much meant for what its name implies - unevenly lit screens. These differences are sometimes not even visible to the human eye, but they are technically there. Toying around with this parameter will apply an extra filtering, i.e. try to eliminate the luminance bias caused by the alternate color channels, trying to compensate the weaker saturation of the primary key color. As you found out, the cases if and when to use it ar hard to rationally understand just on abstract explanations, so keep playing around and practicing until you get an intuitive feeling for this stuff.

 

Mylenium

2 Antworten

R
Community Expert
Rick GerardCommunity Expert
Community Expert
March 4, 2020

When I am giving a demo of Keylight I start by creating an ellipse (circle) with a gradient fill. 100% Blue halfway out and 100% red on the outside edge. Then I apply Keylight and set it up like this:

Status lets you see the ramp or feather of the alpha channel. Changing the color of the outside edge and manipulating the Screen Gain and Screen Balance will show you how both these controls change the blending between colors. Blue and Red is a good place to start, but you should try other colors. The status viewing option is a great place to start when setting the Screen Gain and Screen Balance. Then switching back and forth between Combined Matte, Screen Balance and Final Result will help you get these controls set up very quickly.

 

When you get the edges as good as you can get it is time to tweak Screen Blur, then work through the Screen Matte settings. This process is a lot faster if you keep switching back and forth between the Combined Matte and Final Result display modes.

 

The last step is color correction and light wrap you get with the Foreground and Background controls. You can also do some fine-tuning of the color by adjusting Despil and Alpha bias colors. 

 

Running through the process using a shape layer and a gradient fill will help you understand how the controls work and help you start pushing the controls in the right direction the first time you move them.

    X
    xlistax52479645Autor
    Participating Frequently
    March 5, 2020

    Thanks. I try it!

    Mylenium
    MyleniumAntwort
    Legend
    March 4, 2020

    Screen balance is pretty much meant for what its name implies - unevenly lit screens. These differences are sometimes not even visible to the human eye, but they are technically there. Toying around with this parameter will apply an extra filtering, i.e. try to eliminate the luminance bias caused by the alternate color channels, trying to compensate the weaker saturation of the primary key color. As you found out, the cases if and when to use it ar hard to rationally understand just on abstract explanations, so keep playing around and practicing until you get an intuitive feeling for this stuff.

     

    Mylenium

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