Adobe After Effects CS3 Uživatelský manuál stáhnout pdf (Strana 452)

100

101

AFTER EFFECTS CS3

User Guide

447

7 Specify the Edge Threshold, which is a soft cutoff for removing low-opacity pixels that can cause unwanted noise

in the image background.

8 Select Invert Extraction to reverse the foreground and background regions.

9 Set Blend With Original to specify the degree to which the resulting extracted image blends with the original

image.

Linear Color Key effect

Linear keys create a range of transparency across an image. A linear key compares each pixel in the image to the key

color you specify. If the color of a pixel closely matches the key color, it becomes completely transparent. Pixels that

don’t match as well are made less transparent, and pixels that don’t match at all remain opaque. The range of trans-

parency values, therefore, forms a linear progression.

The Linear Color Key effect uses RGB, hue, or chroma information to create transparency from a specified key color.

This effect works with 8-bpc, 16-bpc, and 32-bpc color.

See also

“Keying overview and tips” on page 268

“Matte Choker effect” on page 450

“Simple Choker effect” on page 451

Apply the Linear Color Key effect

In the Effect Controls panel, the Linear Color Key effect displays two thumbnail images; the left thumbnail image repre-

sentstheunalteredsourceimage,andtherightthumbnailimagerepresentstheviewyou’veselectedintheViewmenu.

You can adjust the key color, the matching tolerance, and the matching softness. The matching tolerance specifies

how closely pixels must match the key color before they start becoming transparent. The matching softness controls

the softness of edges between the image and the key color.

You can also reapply this key to preserve a color that was made transparent by the first application of the key. For

example, if you key out a medium-blue screen, you might lose some or all of a light-blue piece of clothing your

subjectiswearing.Youcanbringbackthelight-bluecolorbyapplyinganotherinstanceoftheLinearColorKeyand

choosing Keep This Color from the Key Operation menu.

1 Select a layer as the source layer, and then choose Effect > Keying > Linear Color Key.

2 In the Effect Controls panel, choose Key Colors from the Key Operation menu.

3 ChooseacolorspacefromtheMatchColorsmenu.Inmostcases,usethedefaultRGBsetting.Ifyouhavetrouble

isolating the subject using one color space, try using a different color space.

4 IntheEffectControlspanel,chooseFinalOutputfromtheViewmenu.Theviewyouchooseappearsintheright

thumbnail and in the Composition panel. If you need to see other results, work in one of the other views:

Source Only Shows the original image without the key applied.

Matte Only Shows the alpha channel matte. Use this view to check for holes in the transparency. To fill undesired

holes after you complete the keying process, see “Close a hole in a matte” on page 271.

1 2 ... 447 448 449 450 451 452 453 454 455 456 457 ... 676 677

Komentáře k této Příručce

Avenue 17 24 Apr 2024 | 16:19:09

What talented message

Adobe After Effects CS3 Uživatelský manuál Strana 452

Komentáře k této Příručce

Související produkty a manuály pro Software Adobe After Effects CS3