Flashcard Background Images Darker than Other Blocks

Hi People,

I've been adding the same images to alternating blocks within a module I'm developing. Unfortunately, I've found that when I use a Flashcard block, the images go very dark.

This is what the background should look like:

This is what the same background looks like with a flashcard.

I read another post which referred to overlays but I can't see an overlay setting in any block.

Thoughts?

Andrew