Sometimes in a design it's nice to add colour effects to an image to get the desired feel or make the page really stand out.
RapidStudio's desktop software allows you to add colour effects to any of the images you've used in an album,
Simply look in the left panel (where you find backgrounds, frames etc.), you'll see there is a panel with various "effects"
One of the effects should be black and white, but there are others you may use as well.
Simply drag the effect onto your photo (on the page of the book) and it will be applied.