Difference between “Empty area” and “Transparency channel” and “Alpha channel”

New to photo editing, so I’ve got some conceptional confusion about the colors and channels,

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  1. In photoshop, we can create text layer, we can have text on top of an “empty space” the checker board, then what is the color of the checker board, from what I can see the checker board does not have color information, so what exactly is the empty area?

  2. Photoshop treats the fourth channel as Transparency channel, but even if I do not have this channel I still have Transparency in the empty area, so I can control an area’s transparency with transparency channel, or set it to “totally empty”, really do not understand the difference between “Empty area” and “Transparency channel” and “Alpha channel”

So when I want to have transparency background, do I need to erease the part that should be transparent, or make a “Transparency channel” or “Alpha channel”?

Answer

All documents in Photoshop must have a width and a height. If there is a width and a height, but no pixel data, the area is defined as “empty”. “Empty area” encompasses the document canvas without pixel data and is used to describe areas between pixel data and the canvas edges.

When exporting/saving Photoshop does not save/export the “empty area”.

All “empty areas” are transparent.

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Transparency is defined as an area which has no pixel data. No color, no value, nothing. If you want to control transparency in Photoshop, that is done by adding or removing pixel data in Layers or color Channels.

There is no “transparency channel” in Photoshop. The pixel data on layers defines transparency.


An Alpha Channel is a saved selection. Similar to a layer mask, an Alpha channel merely indicates a specific area on the open document. There’s some liberty taken by Adobe – using “Alpha” in a more broad sense where customarily “Alpha” has meant transparency.. that’s not always the case within Photoshop. Alpha Channel, in Photoshop, merely means “extra”.

Attribution
Source : Link , Question Author : Dew , Answer Author : Scott

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