I need a print made into a gradient print file.

Description

Hi all!
I have a graffiti print but need a new file created where the print is turned into a black colour faded into my graffiti print so it can be applied to bottom of some leggings which i have attached. So the top half is a black block colour then faded with gradient into my pattern.
I have attached the leggings to give an idea of the whole image and then a cropped image of the black faded into the pattern. My original graffiti print file is too large to attach so i will send that on in due course.
Many thanks.