Differential D20782 Diff 56874 reference_manual/layers_and_masks/split_alpha.rst

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reference_manual/layers_and_masks/split_alpha.rst

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		1		.. meta::
		2		:description:
		3		Split Alpha: how to work with color and alpha channels of the layer seperately
		4
		5		.. metadata-placeholder
		6
		7		:authors: - Dmitry Kazakov <dimula73@gmail.com>
		8		:license: GNU free documentation license 1.3 or later.
		9
		10		.. index:: Layers, Transparency, Alpha channel, Game
		11		.. _split_alpha:
		12
		13		===========
		14		Split Alpha
		15		===========
		16
		17		Sometimes (especially in game development) artists need to work with alpha channel of the texture separately. To assist such workflow Krita has a special :menuselection:`Split Alpha` functionality. It allows splitting alpha channel of a paint layer into a separate Transparency Mask, work with it in an isolated environment and merge back when finished.
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		19		How to work with alpha channel of the layer
		20		-------------------------------------------
		21
		22		#. \|mouseright\| the paint layer in the layers docker.
		23		#. Choose :menuselection:`Split Alpha->Alpha into Mask`
		24		#. Use your preferred paint tool to paint on the Transparency Mask. Black paints transparency (see-through), white paints opacity (visible). Gray values paint semi-transparency.
		25		#. If you would like to isolate alpha channel, enter Isolated Mode by \|mouseright\| + :menuselection:`Isolated Mode` (or :kbd:`Alt` + \|mouseleft\|)
		26		#. When finished editing the Transparency Mask, \|mouseright\| on it and select :menuselection:`Split Alpha->Write as Alpha`
		27
		28		How to save a PNG texture and keep color values in fully transparent areas
		29		-------------------------------------------------------------------------------------
		30
		31		Normally, when saving an image to a file, all fully transparent areas of the image are filled with black color. It happens because when composing the layers of the image, Krita drop color data of fully transparent pixels (for efficiency reason). To avoid this of color data loss you can either avoid compositing of the image (limit image to only one layer, without any masks or effects) or use the following method:
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		33		#. \|mouseright\| the layer in the layers docker.
		34		#. Choose :menuselection:`Split Alpha->Alpha into Mask`
		35		#. \|mouseright\| on the created mask and select :menuselection:`Split Alpha->Save Merged...`