PFClean: Colour Balance
In this tutorial you will learn how to use the Colour Balance effect in PFClean’s Workbench to correct colour shifts and restore clips to a more neutral look.
To learn this tutorial you will need to download and use the footage below.
01. Importing Clips
In the Media Manager, import the clips provided for this tutorial. Then create a Workbench node and connect it to the Media Bin. Double click the Workbench node to open.
02. The Colour Balance Effect
The Colour Balance effect restores colour shifts, for example caused by dye fading, by mapping source colours to target colours. The source colours are usually sampled from the image, but can also be specified manually, and then transformed into more neutral target colours.
When using the Colour Balance effect, you have a wide range of options to refine both source and target colours to achieve the best possible results for your media.
Creating the Effect
In the Workbench, create the Colour Balance effect. The clip’s highlights, midtones and shadows are automatically sampled and displayed in the Source Colours tab.
03. Adjusting Source Colours
By default, only chrominance values are sampled. You can change this individually for the black, balance and white points with the drop down menus. Selecting Luminance only samples luminance information and can be used to restore a more natural contrast range without affecting colour, while RGB samples both, chrominance and luminance. Select RGB for Black Point, Balance Point and White Point. We need to re-sample the image for these changes to have an effect. Click Balance Frame to do this.
The source colours define the colour present in the unrestored image. These will then be mapped to target colours. The source colours can be adjusted or sampled manually if required. Click and drag the indicator in the Balance Point colour wheel to see the effect.
To sample a source colour, click the Black Point, Balance Point or White Point button and clicking or drawing a sample rectangle in the Cinema.
If you are unhappy with your sample, you can simply sample a different region of the frame or click Balance Frame to auto-sample the current frame. You can also change the result of the sample by adjusting the colour wheels or any of the other controls in the Source Colours tab.
04. Animating Parameters
In some cases, the amount of colour shift varies throughout clips. To successfully tackle varying colour shift, you can animate the Colour Balance parameters.
Go to the last frame and auto-sample the source colours in this frame by clicking Balance Frame.
This has created a keyframe for the last frame. You also implicitly created a keyframe when you sampled and adjusted the source colours in the first frame earlier. Use the and buttons in the Cinema to jump between the first and last frame to compare the different keyframe values. Use the cursor keys to step through the clip and see how the keyframed results have been interpolated through the clip.
You can also view and edit keyframes in the Workbench’s F-Curve editor. Click this button to open the editor. The F-Curve editor is not part of this tutorial, but you can find out more about editing f-curves in PFClean by clicking the button.
Clicking Balance Clip will automatically sample the source black point, balance point and white point for all frames individually.
Please note that clicking either, Balance Frame or Balance Clip will overwrite the current parameters, unless they have been locked in the Offsets tab, which is described below.
The colour shift in the tutorial clips is the same for all frames and there is no need to animate the Colour Balance parameters. Go to the last frame, then click Constant to apply the same correction to all frames. Then step through the frames again. You can see the same result for all frames.
05. Target Colours
The Colour Balance effect maps the source colours to the default neutral colours in the Target Colours tab. You can adjust or sample target colours the same way as the source colours. When the Target Colours tab is visible, selecting Black Point, Balance Point or White Point will sample a target colour rather than a source colour. You can also adjust the target colour wheels, the target luminance or select a colour from a colour picker by clicking the area below the individual wheels.
06. RGB Curves
The RGB Curves tab shows the RGB look-up tables that are used to balance the clip. You can directly modify the curves by clicking and dragging the spline points with the left mouse buttons.
The offsets tab provides an overview of source and target colours. You can edit each value separately, either by entering a value with the keyboard, or by clicking and dragging inside the box. Enabling Gang will modify the Red, Green and Blue value of a row at the same time. Each row can also be reset individually with the Reset button. Enabling Lock prevents further adjustment to a source or target colour. Make sure Lock is pressed for both Balance Point and Balance Target. Then click Balance Frame. Notice how all values have been re-sampled, except the locked Balance Point and Balance Target.
08. Reusing Colour Balance Parameters
You can store the current parameters of the Colour Balance effect in an effect preset. Click Store in the Presets section to create a new preset. Then click the > button next to the clip thumbnail to jump to the second clip. Create a Colour Balance effect for the second clip, select the preset and click Recall. Both tutorial clips now have their colour restored to the same standard.