Issue with images appearing darker than they are

Site URL: http://florencehb.squarespace.com/work/project-three-fylys

Hi there!

I’m having an issue where on the page, the drawing of the four rats should be much lighter. The background is white when I open it in other programs. If I change the layout of the image block so the text is beneath the image, the image appears correctly again. It is in the RGB colour profile, so that shouldn’t be the issue. Does anyone know what’s going on? Here is the original image for reference. 

Please see the following.

And here is an example of changing the opacity with your image as test.

Before.

After.