How to connect two image backgrounds for sections of a WEB site design?

Question

User interface

I'm making a site layout, setting the background as images, but I really want to make the site's background seamless.
How to connect two backgrounds so that the edges of the images are not visible, to make the background merge?
Thank you all in advance.

Answer 1

1. Layer with an alpha channel (most likely it will turn out on a tin).
2. Fill the background of the picchi with the main color and move it to alpha by the end of the picchi.
The second option is better, since the first one can give unexpected results, and transitions between uncontrolled colors will give an artifact in the form of a gray transition.