Version: 2.82a (Linux 64)
How to reproduce:
- Open the attached file and render the frame.
- In the display_channels menu in the header of the Image Viewer, select "Color" (Not "Color and Alpha")
- Mouse over the pixels of the image and Compare the RGB values with the displayed values.
- Display the individual RGB color channels as well
The above image looks as though the rim of the shape is solid grey, but in fact the explicit RGB values do fade from grey to black, due to the blur node.
When viewing an image in Color without alpha, or in Red, Green, or Blue Display mode, the image viewer seems to "pre-divide", or perhaps "un-premultiply" the RGB values, which causes incorrect values to display. This makes it very difficult for the user to work with alpha channels!
Adding an Alpha Convert node makes matters even worse:
Now, the explicit RGB values really are a solid grey, but in the image view the rim is displayed as getting brighter! Not a good workflow at all!