Incorrect alpha when rendering to PNG

I use rendering into PNG frames and I just realized that alpha is not saved correctly. The attached image shows how white text looks on white background (put together in Photoshop). If the alpha were correctly saved, the picture would be all white, but instead it shows gray outlines. This does not happen when saving TIFF files instead.

Have I missed something or is there something wrong with the PNG export?

fusion_png_alpha.png (13.81 KiB) Viewed 1049 times

Have you tried the "pre-Divide by Alpha" option in the PNG saver?

Clipboard01.jpg (37.49 KiB) Viewed 1026 times

Have you tried the "pre-Divide by Alpha" option in the PNG saver?

No I haven't. And yes, it indeed helps. Not that I understand why it should be needed, but the result looks OK now. Thanks for the hint!

PNGs by convention do not store premultiplied color.

PNG handling is badly slow in Fusion.