With all this going on, it seems like a good time for some examples on how you can set up a chroma key material in UE4. You can read about that, including some amazing projects, in Tim Sweeney's post surrounding WWDC here. While it was in the release notes, our notes can be pretty long and it is easy to forget about features that are buried deep within them, especially if you had no reason to use them at the time.ĪR is on the rise with many new tools and devices being supported all the time UE4's recent support of ARKit and ARCore are a testament to this. That post led to me mocking up a very basic chroma key function called Chroma Key Alpha that was added to UE4 a while ago. This page covers some Color Theory to help understand Hue, Chroma, Luminance, etc.A bit over two years ago, someone on the UE4 AnswerHub asked about chroma keying (a.k.a. See also Blue Screen which does color based alpha selection but is a bit simpler. A bit of experimenting is required to find the correct values for each clip. The higher the value, the more of the background is removed. These three parameters determine the tolerance of the chroma keying. This is useful if your color selection did not turn out that well. The fatter the choice, the more the selected areas are filled towards the rim (AKA more featuring for fatter choices). The remaining options ("Fat", "Normal" and "Skinny") create a gradual transition between transparent and opaque. This means there will be no blue between the removed parts and the remaining parts whatsoever, and this option is useful if your chroma key turned out to be perfect. Any part of the image/video is either fully opaque and fully transparent. "Hard" means there is no featuring (edges are not smooth at all). The higher the value, the smoother the edges of your color selection will be. This slider determines the smoothness of the edges. If the Edge Mode is set to slope, you can use the "slope" slider. Previews of video chroma keyed using HCI will be slow since it has to calculate values for every single pixel.Įdge Mode Options are: Hard, Fat, Normal, Skinny, Slope So if RGB isn't producing good results then try on of the other options. While RGB should yield the sharpest and best results, sometimes (as I have seen from experience) the other option, HCI & ABI, can yield much better results than RGB. These different options yield different results. Selection Subspace options are: RGB (Red Green Blue), ABI and HCI (Hue Chromacity Intensity) Keeping the selected color opaque may be more effective if the foreground is simple and the background is complicated When OFF the selected color will be opaque. Invert selection: When ON (default), the selected color will be transparent. This is the color that will be transparent/the only color that is opaque. You can now search for this specific effect in your effects tab.Ĭolor to select: the color to select. If the effect took lots of time to experiment, and you will need to use this effect again, then click on the three horizontal lines in the top right corner, and then click Save effect. At this point, you will need to use Rotoscoping. If you experimented and cycled through all the "selection subspaces", and the background isn't still removed properly, then it is probably too complicated for Kdenlive to remove. If you find it isn't removing the background well, try changing the "selection subspace" and experiment again. Adjust the Delta sliders until the background is removed correctly. Click on the droplet button, and then click on the background part of the clip you want to remove. Add the Chroma-Key effect to the clip.Īfter this, either chose the color using the little droplet button. For simple backgrounds (such as green, blue, red or possibly black), use the Chroma Key effect.įind a clip with a background (preferably multiple, or slightly complex, because the "chroma key effect" can do easy backgrounds such as green or blue). This is better for backgrounds that have less contrast with the foreground, or more complex backgrounds. Chroma-Key allows for some basic feathering (by changing the Edge Mode) and much more fine-grained control over how much & in which way you remove the background. The Chroma-Key is a more advanced version of the Chroma Key effect.
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