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Adjust color and luminance using curves
The curves adjustment of
the Luma Curve and the RGB Curves effects, like the Levels sliders
in the Fast Color Corrector and the Three‑Way Color Corrector effects,
let you adjust the entire tonal range or just a selected range of
colors in a video clip. But unlike Levels, which has only three
adjustments (black level, gray level, and white level), the Luma
Curve and RGB Curves let you adjust up to 16 different points throughout
an image’s tonal range (from shadows to highlights).
 Opening a scope in a Reference Monitor that’s ganged
to the Program Monitor lets you view the luminance, chrominance,
or both values as you make the curves adjustments. If you’re using
the Vectorscope, there should be minimal green shading in the areas
outside of the center of the scope. Areas outside the center define
the level of color saturation. - In the Effects panel, click the triangle to expand
the Video Effects bin, and then click the triangle to expand the
Color Correction bin.
- Drag one of the following effects to the clip in a Timeline
panel:
- Luma Curve
- Adjusts primarily luminance. Keep in mind that adjusting
the luminance does affect the perceived saturation of the colors.
- RGB Curves
- Adjusts both color and luminance.
Note: If
a clip is selected in a Timeline panel, you can drag the effect
to the Video Effects section of the Effect Controls panel.
- In the Effect Controls panel, click the triangle to expand
the Luma Curve or RGB Curves controls.
- (Optional) Do any of the following to set preview options:
To view only the luminance values in a
clip, choose Luma from the Output menu. This option affects only
the preview in the Program Monitor; it doesn’t remove the color
from the video.
To display a before and after view of the clip in
one monitor, select the Show Split View option. You can specify
whether the split view is horizontal or vertical by choosing from
the Layout menu. You can also adjust the relative proportion of
the before and after views.
- (Optional) Click the triangle to expand the Secondary
Color Correction controls if you want to correct the exposure for
a specific color or range of colors. Use the Eyedropper tool or
the other Secondary Color Correction controls to specify the colors
to correct.
- Do one of the following to make curve adjustments:
To adjust the luminance, click to add a
point on the Luma or Master graph and drag to change the shape of
the curve. Bowing the curve upward lightens the clip and bowing
the curve downward darkens the clip. The steeper sections of the
curve represent portions of the image with greater contrast.
To adjust both the color and luminance using the
RGB Curves effect, click to add a point on the appropriate graph
to adjust all color channels (Master), the red channel, the green
channel, or the blue channel. Drag to change the shape of the curve.
Bowing the curve upward lightens the pixel values and bowing the
curve downward darkens the pixel values. The steeper sections of
the curve represent portions of the image with greater contrast.
You can add a maximum of 16 points to the curve. To delete
a point, drag it off the graph.
As you make
adjustments, watch carefully for banding, noise, or polarization
in the image. If you notice any of these, reduce the value you are
adjusting.
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PDF (adobe.com)
