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zhajiangmian wrote: Some problems found are that the mask channel and color will affect the black part of the mask. In theory, it should be just pure color and will not affect each other.[img]file:///C:/Users/Administrator/Desktop/mask2.jpg[/img]

Thank you and welcome here!
Your image hasn't attached correctly, please, can you drag and drop it clicking Upload files or moving your image to the area with "Upload files" in Reply form


Do you talk about Alpha in CentiLeo bitmap node or the Alpha in the render image?
The Alpha Image is accessed if you connect the Alpha channel output port of the CentiLeo Bitmap node.

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zhajiangmian wrote: Sorry, it's my first post, I uploaded the screenshot again

You see reflected color from the other object because you have checked On the flag "Reflections & Refractions" in Mask Aov settings.
In material settings you have tinted the color of the material that is hit.
All is correct here. Just switch off "Reflections & Refractions".