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</div><div class="twikiRevInfo"><span class="twikiGrayText"><span class="twikiToolbarElem">Cinelerra.OverlayMode</span><span class="twikiToolbarElem">r1.5 - 26 Jan 2004 - 01:03 - <a class="twikiLink" href="../Main/AlexFerrer">AlexFerrer</a></span><span class="twikiToolbarElem"><a href="#TopicEnd">topic&nbsp;end</a></span></span></div></div>
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<h3><a name="Overlay_Mode_s"> </a><a name="_Overlay_Mode_s"> </a> <a class="twikiLink" href="OverlayMode">Overlay Mode</a>s </h3>
<p />
Every video <a class="twikiLink" href="MediaTrack">MediaTrack</a> has an <a class="twikiLink" href="OverlayMode">OverlayMode</a>, accessible by expanding the track. The overlay mode is a pulldown menu on the left under the fader. When collapsed, it displays an icon representing the current overlay mode.
<p />
<img src="../../../pub/Cinelerra/CinelerraImages/overlay_mode.png" alt="overlay_mode.png" /><br>
Select the expand track toggle to view all the options for a video track if you can't see the overlay mode. The overlay mode of video tracks is normal by default. Select other modes by clicking the overlay button and selecting an item from the popup menu.
<p />
Overlay modes are processed inside the projector stage of compositing. The different modes are summarized below.
<p />
<h4><a name="Normal"> </a> Normal </h4>
<ul>
<li> Uses a traditional Porter-Diff equation to blend tracks with alpha. When no alpha exists in the project color model, the new track always replaces the output.
</li>
</ul>
<h4><a name="Addition"> </a> Addition </h4>
<ul>
<li> In this mode, whatever is in the output is added to the current track. The result is blended based on the current track's alpha onto the output.
</li>
</ul>
<h4><a name="Subtraction"> </a> Subtraction </h4>
<ul>
<li> In this mode, the current track is subtracted from the output and the result is alpha blended onto the output.
</li>
</ul>
<h4><a name="Multiply"> </a> Multiply </h4>
<ul>
<li> is the most useful operation. The current track is multiplied by the output and the result blended onto the output. Usually a black and white image with no alpha channel or a white title on a black image is used as the current track. With the multiply operation, only the output portions under the white area show.
</li>
</ul>
<h4><a name="Divide"> </a> Divide </h4>
<ul>
<li> divides the current track by the output and the result is blended into the output. It usually results in overloaded levels.
</li>
</ul>
<h4><a name="Replace"> </a> Replace </h4>
<ul>
<li> does no blending and overwrites the output with the current track. 
</li>
</ul>
<p />
-- <a class="twikiLink" href="../Main/AlexFerrer">AlexFerrer</a> - 21 Dec 2003 <strong><em>from <a class="twikiLink" href="SecretsOfCinelerra">SecretsOfCinelerra</a></em></strong>
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<a name="Actions"> </a><span class="twikiHidden"><br /></span><div class="twikiTopicAction"><a href="http://www.ftconsult.com/twiki/bin/edit/Cinelerra/OverlayMode?t=1129908177"><b>Edit</b></a> <span class="twikiSeparator">|</span> <a href="http://www.ftconsult.com/twiki/bin/attach/Cinelerra/OverlayMode">Attach image or document</a> <span class="twikiSeparator">|</span> <a href="http://www.ftconsult.com/twiki/bin/view/Cinelerra/OverlayMode?skin=print.pattern">Printable version</a> <span class="twikiSeparator">|</span> <a href="http://www.ftconsult.com/twiki/bin/view/Cinelerra/OverlayMode?raw=on">Raw text</a> <span class="twikiSeparator">|</span> <a href="http://www.ftconsult.com/twiki/bin/oops/Cinelerra/OverlayMode?template=oopsmore&param1=1.5&param2=1.5">More topic actions</a><br />Revisions:  | r1.5 | <a href="http://www.ftconsult.com/twiki/bin/rdiff/Cinelerra/OverlayMode?rev1=1.5&rev2=1.4">&gt;</a> | <a href="http://www.ftconsult.com/twiki/bin/view/Cinelerra/OverlayMode?rev=1.4">r1.4</a> | <a href="http://www.ftconsult.com/twiki/bin/rdiff/Cinelerra/OverlayMode?rev1=1.4&rev2=1.3">&gt;</a> | <a href="http://www.ftconsult.com/twiki/bin/view/Cinelerra/OverlayMode?rev=1.3">r1.3</a> <span class="twikiSeparator">|</span> <a href="../../rdiff/Cinelerra/OverlayMode">Total page history</a> <span class="twikiSeparator">|</span> <a href="http://www.ftconsult.com/twiki/bin/search/Cinelerra/SearchResult?scope=text&regex=on&excludetopic=OverlayMode&search=Overlay%20*Mode%5B%5EA-Za-z0-9%5D">Backlinks</a></div>
<div class="twikiTopicInfo twikiRevInfo twikiGrayText twikiMoved"><i>Cinelerra.OverlayMode moved from Cinelerra.OverlayModes on 21 Dec 2003 - 19:09 by <a class="twikiLink" href="../Main/AlexFerrer">AlexFerrer</a> </i> - <a title="Click to move topic back to previous location, with option to change references." href="http://www.ftconsult.com/twiki/bin/rename/Cinelerra/OverlayMode?newweb=Cinelerra&newtopic=OverlayModes&confirm=on">put it back</a></div>
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