Alpha channel


Alpha Channel in

alpha channel (Alpha Channel) refers to a transparent image and translucency. For example: a 16-bit storage of pictures, may 5 represent red, green represents 5, 5 denotes blue, and an Alpha. In this case, it either means transparent or not. A 32-bit image stored in each 8 bits red, green and blue, and alpha channel. In this case, light may not represent a transparent or opaque, may also represent the alpha channel 256 of translucency.

in new or existing in the Alpha channel, may be any selection as a mask. You can edit the Alpha channel, which add or remove color, and can mask color and opacity specified settings. Popular to say that as the transparent effect when the chart. Generally alpha value is taken between 0 and 1. Channel into three channels. That is, there are three functions.

Creating Alpha Channel

1, hold down the Alt key (Windows) or Option (Mac OS) and click "New channel" button at the bottom of the "channel" panel, or from "channel" panel menu select "New channel."

2, specify options in the "New Channel" box.

3, drawing on the new channel to mask image areas.

Alpha channels and masks

When you select a portion of an image, the unselected area will be "masked" or protected to avoid being edited. Therefore, after you create a mask, when you want to change the color of the image of a region, or the region to apply the filter or other effects, you can isolate and protect the rest of the image. You can use masks when performing complex also image editing such as gradually the color or filter effects to an image. Opacity Mask B. C. opacity mask for protecting the mask Examples A. Background and edit "Butterfly" for protecting a "butterfly" and the background for the colored background and the part of the "Butterfly" colored translucent mask Version masks stored in the Alpha channel. Masks and channels are grayscale images, so you can use painting tools, editing tools and filters like any other image editing as edit them. On the mask with black painted area will be protected; and areas on the mask is painted with white editable region.

Use Quick Mask mode to convert the selection to a temporary mask for easier editing. Quick Mask will appear as a color overlay with adjustable opacity. You can use any drawing tool to edit the Quick Mask using filters or modify it. After you exit Quick Mask mode the mask is converted back to a selection on the image.

to be stored in a more permanent selection may be the selection as Alpha channel. Alpha channel to selection as the "channel" panel to edit a grayscale mask. Once a selection as Alpha channel, you can always reload the selection or the selection loaded into other images.


pixel value calculating

arbitrary image alpha channel in the point were as follows:

< h2> channel Type

main channel

to open a new image, the color information is automatically created channels. Determining a number of color mode image created color channels. Eg, RGB image has four default channels: red, green and blue each have a channel, and a composite image for editing a channel (main channel).

spot channel

spot channels is three RGB colors other than the user to add their own colors. And as the main channel, it is also used to store color information. Just remember that, after you have finished the effect you want to merge into the main channel inside.

Common Channel

normal channel is not used to store color information. But it is used to store the selection.

Color Depth

standard depth of color usually have the following:

8-bit color, each pixel can be displayed as a color number of 2. 8 square, 256 colors.

16-bit High-color, 16-bit color, the color number of each pixel 16 can be displayed is a power of two, i.e., 65,536 colors.

24-bit true color, the color number of each pixel can be displayed is 24, i.e. 24 th power of 2, approximately 16.8 million colors.

32-bit true color, i.e., the 24-bit true color image based on a further increase transparency information represents the Alpha channel image.

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