Denis Konovalyenko:
The current implementation is capable of handling foreground fills only. Thus, the target is to make it consistent among background, foreground and font colours. So, if any mentioned areas contain an excluded colour, the cell must also be excluded from extraction. Also, inline formatting font colours must be considered.
Below is an example of the aforementioned cases:

And last but not least, there were new preset colours available after 2013 and they are out of spec. However, it would be nice, if, at least, the main ones \(Dark Red, Red, Orange, Yellow, Light Green, Green, Light Blue, Blue, Dark Blue, and Purple\) could be added for processing.
For more information please refer to the attached document.