Reasons and countermeasures for when the transparency of the imported video or still image is dark or light

Question

I read a video or image with transparency (alpha) set, but the transparency is darker or lighter than the system I created. Please tell me the reason and how to deal with it.

Answer

There are two possible causes:

  • Alpha mode (transparency) difference
  • Differences in blending modes

Other related matters are listed as supplements at the end.

Alpha mode (transparency) difference

This occurs because the alpha (transparency) processing used when creating videos and images differs from the transparency settings currently used when handling that material on DaVinci Resolve.

Right-click a video or still image in the media pool and select "Change Alpha Mode" to select from "ignore (none)", "premultiplied", "inverted", and "straight".

Alternatively, right-click a video or still image in the media pool and select <Clip Attributes>

Select from "none (ignore)", "premultiplied", "inverted", and "straight" in alpha mode.

Differences in blending modes

The expression of transparency changes depending on the composition mode when overlapping clips with transparency.

Select the clip to add transparency on the timeline, select "Inspector" on the upper right, and select from "Compositing Mode" in "Compositing".

If you select a blending mode from "Blending Mode", you can select various blending modes.

supplement

If you change the color with the Color Corrector node of Fusion, the transparent place will be colored

Check "Pre-Divide/Post-Multiply" in "Option" of the inspector of the Color Corrector node.
Causes the image pixel values ​​to be divided by the alpha value before the transform and multiplied by the alpha value after the transform. (Transparency is removed before processing, and the same transparency as the original is applied after processing.) This causes incorrect added images when color correcting images with premultiplied alpha channels. prevent you from doing so.

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