Premultiplied alpha - Revision history

Vegard: /* Solution */ gamma correction

2019-12-19T10:31:17Z

Solution: gamma correction

← Older revision		Revision as of 10:31, 19 December 2019
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	This allows texture filtering to combine the RGB and alpha components separately and produce accurate blending results.		This allows texture filtering to combine the RGB and alpha components separately and produce accurate blending results.

			Note that if sRGB textures are used (and they probably shouldn't be) then the process is different; see the article on [[Gamma\|gamma correction]] for more information.

	=== See also ===		=== See also ===

Vegard: /* See also */

2019-12-19T08:58:23Z

Vegard at 08:52, 19 December 2019

2019-12-19T08:52:24Z

← Older revision		Revision as of 08:52, 19 December 2019
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	* multiply RGB values by the alpha component when loading textures		* multiply RGB values by the alpha component when loading textures
	* use <tt>glBlendFunc(GL_ONE, GL_ONE_MINUS_SRC_ALPHA)</tt>		* use <code>glBlendFunc(GL_ONE, GL_ONE_MINUS_SRC_ALPHA)</code>

	This allows texture filtering to combine the RGB and alpha components separately and produce accurate blending results.		This allows texture filtering to combine the RGB and alpha components separately and produce accurate blending results.

Vegard: new page

2019-12-19T07:15:41Z

new page

New page

=== Problem ===

When blending a partially transparent image on top of a background image you can get artifacts in areas which are not fully transparent and not fully opaque. The problem stems from the use of texture filtering, which will interpolate values from nearby pixels without taking transparency into account.

=== Solution ===

Use premultiplied alpha; usually this means:

* multiply RGB values by the alpha component when loading textures
* use <tt>glBlendFunc(GL_ONE, GL_ONE_MINUS_SRC_ALPHA)</tt>

This allows texture filtering to combine the RGB and alpha components separately and produce accurate blending results.

=== See also ===

* http://www.adriancourreges.com/blog/2017/05/09/beware-of-transparent-pixels/

[[Category:Graphics programming]]

← Older revision		Revision as of 08:58, 19 December 2019
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	* http://www.adriancourreges.com/blog/2017/05/09/beware-of-transparent-pixels/		* http://www.adriancourreges.com/blog/2017/05/09/beware-of-transparent-pixels/
			* https://limnu.com/premultiplied-alpha-primer-artists/

	[[Category:Graphics programming]]		[[Category:Graphics programming]]