Windows 10 Technical Preview

Windows 10 Technical Preview was the first phase of Windows 10's Insider Program. It was renamed to Insider Preview in build 10074. Due to no significant wallpaper changes occuring beyond the development of the RTM release, this page will only cover the wallpaper development leading up to that point, however it still covers the development even after it became Insider Preview.

Builds 9780 to 9888
At this point in development, 10's wallpapers are identical to 8.1's, except that img0 and img1 have been swapped, resulting in 8.1's img1 becoming the default wallpaper.

Builds 9900 to 10151
All of the Lines and colors wallpapers leftover from 8.1 have been removed and replaced with a completely different theme, consisting of stock photos mostly licensed from Getty Images, most of which use rights-managed licenses. None of these appear in the final release, as they were simply placeholders until Steve McCurry and Chad Copeland's wallpapers were added. However, build 10138 replaces the default wallpaper with the wallpaper that would become img2 in the final release, although the other wallpapers remain intact at this point. The Flowers theme, which has been present since 8, also remains intact throughout.

Builds 10154 to 10158
With the exception of img13, all of the placeholder wallpapers were replaced with photos taken by McCurry and Copeland. The wallpaper that would later become img1 is the default wallpaper here, with the previous default wallpaper being reallocated to img1.

Build 10159 onwards
At this point, the default wallpaper has been changed to the one that appears in the final release, while img13 is changed to a panoramic version of img4. Microsoft described the new wallpaper as an "interesting change". As a result, all of the McCurry and Copeland wallpapers added in build 10154 had their numbers increased by one.

Builds 9780 to 9888
At this point in development, 10's lock screen wallpapers are identical to 8.1.

Builds 9900 to 10158
All of 8.1's lock screen wallpapers have been replaced with new ones; much like the desktop wallpapers, these are also mostly stock photos licensed from Getty, although most of them use a royalty free license instead. With the exception of the single color img103 which was later reallocated to img105, none of these appear in the final release, as they were simply placeholders until Steve McCurry and Chad Copeland's wallpapers were added.

Build 10159 onwards
At this point, all of the lock screen wallpapers are replaced with the same ones that appear in the RTM release onwards.

User Account Pictures
Most likely, Windows 10 used account pictures from Windows 8 up to build 1507, but currently it's not verified. Please remove this block if the information is verified and W10TP used only Windows 8 UAPs