Auto Color and Auto Contrast effects
The
Auto Color effect adjusts the contrast and color of an image after
analyzing the shadows, midtones, and highlights of the image. The
Auto Contrast effect adjusts the overall contrast and mixture of
colors. Each effect maps the lightest and darkest pixels in the
image to white and black, and then redistributes the intermediate
pixels. The result is that highlights appear lighter and shadows appear
darker.
Because Auto Contrast and Auto Color don’t adjust channels individually,
they don’t introduce or remove color casts.
The
Auto Levels effect uses many of the same controls as the Auto Color
and Auto Contrast effects.
A quick way to remove (or at least reduce) the
flicker caused by fluctuations in exposure and color from one frame
to the next is to apply the Auto Color effect. This is useful, for
example, in reducing the flicker of old film or for correcting for
the flickering color of a light source.
These effects work with 8-bpc and 16-bpc color.
- Temporal Smoothing
- The range of adjacent frames, in seconds, analyzed to determine
the amount of correction needed for each frame, relative to its surrounding
frames. If Temporal Smoothing is 0, each frame is analyzed independently,
without regard for surrounding frames. Temporal Smoothing can result
in smoother looking corrections over time.
- Scene Detect
- If selected, frames beyond a scene change are ignored when surrounding
frames are analyzed for temporal smoothing.
- Black Clip, White Clip
- How much of the shadows and highlights are clipped to the
new extreme shadow and highlight colors in the image. Setting the
clipping values too high reduces detail in the shadows or highlights.
A value in the range from 0.0% to 1% is recommended. By default,
shadow and highlight pixels are clipped by 0.1%—that is, the first
0.1% of either extreme is ignored when the darkest and lightest
pixels in the image are identified. The lowest and highest values
within the range after clipping are then mapped to output black
and output white. This method ensures that input black and input
white values are based on representative rather than extreme pixel
values.
- Snap Neutral Midtones (Auto Color only)
- Identifies
an average nearly neutral color in the frame and then adjusts the
gamma values to make the color neutral.
- Blend With Original
- The transparency of the effect. The result of the effect
is blended with the original image, with the effect result composited
on top. The higher you set this value, the less the effect affects
the layer. For example, if you set this value to 100%, the effect
has no visible result on the layer; if you set this value to 0%,
the original image doesn’t show through.
