Where I have seen this problem on my Glo it has been because the original image is coded as shades of grey instead of black-and-white. The device seems to display the image in two steps, first as black and white, then it adds the colours or shades of grey. I think that is what gives the effect of the image briefly appearing dark and then becoming lighter.
The only solution I know of is to edit the image in the original book to turn it into a black-and-white image. On Linux I use the Colors > Threshold function in gimp to reduce the image from grey scale to two colours.
Edit: Attached are screenshots from my Glo displaying
this image, first as the original grey scale image, the second as a black-and-white image.