Archive:Kdenlive/Manual/Effects/Alpha manipulation/da: Difference between revisions

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== Effekter - alfamanipulation ==
<span id="Alpha_manipulation"></span>
=== Alfamanipulation ===


=== Generel information om alfamanipulation ===
<span id="General_Information_about_Alpha_Manipulation"></span>
==== Generel information om alfamanipulation ====  


Så vidt jeg ved bruges alfamanipulationseffekter altid i i kombination med en [[Special:myLanguage/Kdenlive/Manual/Transitions/Composite|sammensatte overgange]]. Det er fordi alfamanipulation har at gøre med manipulation af billeders og videoers såkaldte "alfakanal". Alfakanalen er data, som beskriver hvordan to billeder skal kombineres (eller compositeres) til ét. Derfor skal du bruge en sammensat overgang på tidslinjen for at fortælle '''Kdenlive''', at du vil compositere videoerne i to forskellige spor til et billede.  
Alfamanipulation, almindeligvis kendt som chroma-key compositing, er en effekt, som skifter et billedes baggrund ud med en anden baggrund.


{|
Du kan finde mere information på de enkelte effekters sider:
|[[File:Two tracks no transition.png|left]]||Dette billede viser to videospor uden overgange.<br />Projektmonitoren viser, hvordan det øverste spor har forrang, nå der ikke er en overgang i spil.
|}


{|
# [[Special:myLanguage/Kdenlive/Manual/Effects/Alpha manipulation/Blue Screen|Kroma-key]] (for simple chroma-key-effekter)
|[[File:Two tracks composite transition no alpha info.png|400px|left]]||Dette billede viser to videospor med en sammensat overgang men uden alfainformation til at fortælle '''Kdenlive''' hvordan billederne skal kombineres.<br />Med sammensat overgang men uden alfainformation til at beskrive, hvordan sporene skal compositeres er det stadig det øverste spor, som har forrang.
# [[Special:myLanguage/Kdenlive/Manual/Effects/Alpha manipulation/Color Selection|Farvevalg]] (for komplekse chroma-key-effekter)
|}


{|
|[[File:Two tracks composite transition with alpha info.png|400px|left]]||This image shows the situation with Alpha info now added via the blue screen method.<br />The blue screen effect is also known as "Color to alpha" [http://www.mltframework.org/bin/view/MLT/FilterFrei0r-bluescreen0r] and all the blue screen effect does is say that where the video is blue the alpha value is 0 (i.e. transparent).<br />So now that we have alpha information the second tracks image now shows through where the alpha channel says the image should be transparent.
|}


Once you have some alpha channel data in play you can alter the settings in your [[Special:myLanguage/Kdenlive/Manual/Transitions/Composite|composite transition]] to change how the images will combine. See [[Special:myLanguage/Kdenlive/Manual/Transitions/Composite|composite transition]] page for details.


You can also combine two video tracks together using the [[Special:myLanguage/Kdenlive/Manual/Transitions/screen|screen]] transition (if one of them is filmed on a black background).


=== Hint for previewing the alpha manipulation effects ===
==== Effekter i kategorien Alfamanipulation ====
 
# [[Special:myLanguage/Kdenlive/Manual/Effects/Alpha manipulation/Alpha gradient|Alfagradient]]
The preview in Project monitor goes all strange when you select the composite transition in the time line or the video 1 in the time line.
# [[Special:myLanguage/Kdenlive/Manual/Effects/Alpha manipulation/Alpha operations|Alfa-operationer]]
 
# [[Special:myLanguage/Kdenlive/Manual/Effects/Alpha manipulation/Alpha shapes|Alfaformer]]
[[File:Weird preview look.png|400px|left]]
# [[Special:myLanguage/Kdenlive/Manual/Effects/Alpha manipulation/Blue Screen|Chroma-key]]
What the project monitor looks like when you have just selected the composite transition in the time line. This is not what the rendered video will look like.
# [[Special:myLanguage/Kdenlive/Manual/Effects/Alpha manipulation/Color Selection|Farvevalg]]  
To get a look at what the video will render as you need to click Video 1 and then Video 2 in the timeline.
# [[Special:myLanguage/Kdenlive/Manual/Effects/Alpha manipulation/Mask0Mate|Rektangulær alfamaske]]  
<br style="clear: both;"/>
 
[[File:Two tracks composite transition with alpha info.png|400px|left]] What the preview looks like once you select Video 2 in the timeline. This is what the rendered file will look like
<br style="clear: both;"/>
<br />
 
=== Effects in the Alpha Manipulation Category ===
 
# [[Special:myLanguage/Kdenlive/Manual/Effects/Alpha manipulation/Alpha gradient|Alpha gradient]]
# [[Special:myLanguage/Kdenlive/Manual/Effects/Alpha manipulation/Alpha operations|Alpha operations]]
# [[Special:myLanguage/Kdenlive/Manual/Effects/Alpha manipulation/Alpha shapes|Alpha shapes]]
# [[Special:myLanguage/Kdenlive/Manual/Effects/Alpha manipulation/Blue Screen|Blue Screen]]
# [[Special:myLanguage/Kdenlive/Manual/Effects/Alpha manipulation/Color Selection|Color Selection]]
# [[Special:myLanguage/Kdenlive/Manual/Effects/Alpha manipulation/Mask0Mate|Mask0Mate]]
# [[Special:myLanguage/Kdenlive/Manual/Effects/Alpha manipulation/Rotoscoping|Rotoscoping]]
# [[Special:myLanguage/Kdenlive/Manual/Effects/Alpha manipulation/Rotoscoping|Rotoscoping]]
# [[Special:myLanguage/Kdenlive/Manual/Effects/Misc/keysplillm0pup|Key Spill Mop Up]]


=== Compositing Reference Material ===
<span id="Compositing_Reference_Material"></span>
==== Baggrundsmateriale om compositing ====


For some background the Wikipedia article in [http://en.wikipedia.org/wiki/Alpha_compositing alpha compositing] is usefull. See also Porter, Thomas; Tom Duff (1984). "Compositing Digital Images". Computer Graphics 18 (3): p253–259 1984 [http://keithp.com/~keithp/porterduff/p253-porter.pdf pdf]
For noget baggrundsinformation (på engelsk) er Wikipediaartiklen  [http://en.wikipedia.org/wiki/Alpha_compositing alpha compositing] nyttig. Se også Porter, Thomas; Tom Duff (1984). "Compositing Digital Images". Computer Graphics 18 (3): p253–259 1984 [http://keithp.com/~keithp/porterduff/p253-porter.pdf pdf]


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[[Category:Kdenlive]]
[[Category:Kdenlive/da]]

Latest revision as of 13:00, 15 August 2023

Other languages:

Alfamanipulation

Generel information om alfamanipulation

Alfamanipulation, almindeligvis kendt som chroma-key compositing, er en effekt, som skifter et billedes baggrund ud med en anden baggrund.

Du kan finde mere information på de enkelte effekters sider:

  1. Kroma-key (for simple chroma-key-effekter)
  2. Farvevalg (for komplekse chroma-key-effekter)



Effekter i kategorien Alfamanipulation

  1. Alfagradient
  2. Alfa-operationer
  3. Alfaformer
  4. Chroma-key
  5. Farvevalg
  6. Rektangulær alfamaske
  7. Rotoscoping
  8. Key Spill Mop Up

Baggrundsmateriale om compositing

For noget baggrundsinformation (på engelsk) er Wikipediaartiklen alpha compositing nyttig. Se også Porter, Thomas; Tom Duff (1984). "Compositing Digital Images". Computer Graphics 18 (3): p253–259 1984 pdf

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