AE keying skills of later software

Keying, also known as keying, is a special effect of split screen, but the dividing lines of split screen are mostly regular, such as words, symbols, complex graphics or some natural scenery. "Digging" and "filling" are the essence of Keying Technology. In general, the cropped image is the background image; The filled image is the foreground image. Harbin Perfect Power shares AE keying skills with you! The electrical signal used to cut out the image is called the key signal, and the signal source that forms this signal is the key source. Generally speaking, keying technology includes self-key, foreign key and color key.

Methods/steps

Self-key, also called internal key, is a trick that uses one of the signals involved in keying stunt as the key signal to divide the picture, that is to say, the key source and the foreground image are the same image. It requires that the brightness of each point in the key source image must be relatively uniform and high, which is generally used for the superposition of words and graphics. Such as subtitles and signs seen on TV. As a key source signal, there are only two levels. After the non-additive hybrid circuit, the key source signal itself is output at a high level, and the background image is output at a low level.

Compared with the inner key, the key signal of the foreign key is provided by the third key source image, not by the foreground or background image participating in the keying stunt. The first two keys are also called brightness keys because they use the brightness signal component in the key source image to form the key signal.

The color key uses the chromaticity components of the foreground image in two color signals participating in the key technique to form a key signal. Color keys are widely used in TV program production. For example, the weather forecast and some TV plays also use color key stunts, so many exterior scenes can be shot in advance, which can be used to provide background signals when necessary, so that people can perform various performances in various exterior scenes, just like in the studio, and people can fly in the sky and walk in the clouds, giving the audience better artistic effects.

1 color difference key (color difference key)

The working principle of color difference key is different from other linear background removal methods, and more similar to the traditional optical background removal. Its principle is to divide the selected layer into two gray images: the shadow part b represents the number of primary colors found in pixels; The shading part A depends on a color that is very different from the basic color, and the final shading is a combination of the two. It can be used to generate a higher quality back removal effect, and it can also be used for more difficult back removal effects, such as things containing smoke and shadows.

2 color range (color range)

Color Ranges Adjust colors in the same way as color ranges in Photoshop. The best effect occurs when the background contains various changing elements of the primary colors. This method is not as accurate as the color difference key. It is equipped with:

+The eyedropper selects the color to be eliminated.

Choose the color of the straw that will not be eliminated.

Fuzzy fine-tuning the balance of the mask.

Color Space specifies the range of colors removed from the back.

Maximum value/minute. Settings are used to expand and block shadows.

3 Different masks (different shadows)

The difference mask is removed from the back according to the difference between the two layers. In the source layer, pixels similar to the difference layer become transparent. Its settings mainly include:

The view specifies the observation object.

Different LayersSelect the layer to compare with the source layer.

Stretch to fit the image to the size of the source layer.

Matching Tolerance (Matching Tolerance) eliminates the blue spinner.

Matching softness controls the edge of the shadow.

Blur Before Difference uses a blurred background to eliminate particles and neutralize the primary color foreground.

4 extract (extract)

The extraction effect blocks light according to a channel in the image. It is not as sensitive as color range and difference mask. It is equipped with:

The histogram shows the position of pixels in the selected channel. Adjust by using the slider control below or adjusting the gray bar.

Channel Specifies the channel used to select the shadow.

You can fine-tune the expansion and blocking of shadows by adjusting the black and white settings.

5 Linear color key (linear color removal)

The linear color key effect is processed by comparing each pixel in the image with the specified primary color. It works better in solid color areas without translucent objects, such as hair or smoke. It is equipped with:

Preview the source file, or use the eyedropper to specify the basic color.

The view selects what to display, which can be the final output result, source file or coloring.

Main color Select the primary color.

Matching tolerance and matching softness fine-tune shading, and use these two settings to balance each other.

The above are several commonly used keying types. Select the appropriate keying type according to different specific scenarios. When choosing any type, sometimes the background is not very clean, and there are still some uncleaned colors around the image. At this point, you need to use Spill Suppressor to key the uncleared colors again and remove the colors around the back elements to complete your satisfactory creation. The main settings of overflow suppressor are:

(1)① suppression color (suppression color) is used to select the suppression color.

② When ② color accuracy affects color, choose quickly; On the contrary, the choice is better.

③ Suppress the specified amount of color suppression.