The UsePixelEvaluatorForThumbs property is a boolean flag within the Editor.Assets.AssetPreview class. When set to true, this property enables a feature that renders the asset's thumbnail multiple times during a cycle. It then selects the thumbnail with the least alpha (transparency) and the most luminance (brightness). This can be useful for ensuring that the most visually appealing thumbnail is chosen, especially in cases where the asset might have varying levels of transparency or brightness.

To use the UsePixelEvaluatorForThumbs property, you can set it directly on an instance of the AssetPreview class. This property is virtual, allowing for potential overrides in derived classes if custom behavior is needed.

Example usage:

var assetPreview = new AssetPreview();
assetPreview.UsePixelEvaluatorForThumbs = true; // Enable pixel evaluation for thumbnails

By setting this property to true, the asset preview system will evaluate multiple thumbnail renders and choose the best one based on alpha and luminance.