With all my Xara products, I have over 21,000 XAR files that have the special phrase "themecolorscheme" in the filename.
Xara uses these with the Website Templates so that you can double-click a colour scheme in the Local Design gallery or in the On-line Content Catalogue and the Theme colours are changed to one stored in this special XAR file.
Back in the days, Xara designers would have hand-crafted these themes then Xara introduced the Palette from Photo and three Theme Colours, the first two T1 & T2 come with four additional shade. T3 is on it own. You also get Text, Contrasting Text and Page & Pasteboard Backdrops: 16 colours in all.

I have modified a default colour scheme file and thrown in a couple of extras:
  • Four colours for a NavBar: Menu, MenuHover, MenuVisited & MenuBar.
    • I link these into my Website Link Colours.
    • The word NavBar is a presentation of the working Link.

  • A thumbnail of the image used to derive the Palette.
    • It is a Bitmap Fill of the main image before I optimise it and delete the original from the Bitmap gallery.
    • I actually use the On-line Content Catalogue thumb.
    • The Pixabay image has its ID in the thumb so I search on Pixabay directly for the same image and add this Link to the link of the thumb in the design file so I have a solid reference.
    • I set the Image Filename to the search term I used.

I save the colour scheme file as Search_Term_themecolorscheme.xar.

Here is my Cherry_themecolorscheme.xar
You can open this to see its structure.

This is where the fun begins:
  • You do not directly typically open Search_Term_themecolorscheme.xar
  • You drag it onto your design page and your current theme colours are replaced.

DO NOT DO THIS IF YOU CANNOT REVERT TO YOUR HARD EARNED THEME COLOURS - USE CTRL+Z.

My main use is I gain a clutch of images from the client or prepare a set from Pixabay based on the brief.
I build the website or document portfolio.
I present the design and can drop fresh schemes directly allowing the client to pick a scheme or we modify one to best suit.

To create your own.
Open a fresh image onto the Cherry_themecolorscheme.xar design page and with the Photo Tool pick the Palette from Photo icon.
Note all the colour on the page, bar the Menu ones are updated.
Separately tweak the Menu colours.
Save the file to its new name after your add in the source detail I described.

Build your own collection.

Acorn

P.S. If you use this URL (https://cdn.pixabay.com/photo/2018/0...65_960_720.jpg) onto the pop-up of the Choose File button in https://www.xara.com/tools/color-palette-generator/, Xara almost provides the same colours.
I think this shows Xara Cloud has a lot of catching up to do.