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, Windows 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 Windows 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's slightly different from img2 in the final release, although the other wallpapers remain intact at this point. The Flowers theme, which has been present since Windows 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, slightly moved to the left and the light part was recolored to blue.

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, Windows 10's lock screen wallpapers are identical to 8.1.

Builds 9900 to 10158
The Windows 8 lock screen wallpaper set was replaced with a new set of images; much like the desktop wallpapers, these are also mostly stock photos licensed from Getty Images, although most of them use a royalty free license instead. With the exception of img103 (later reallocated to img105), none of the images appeared 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
Windows 10 used the same user account pictures from Windows 8 and 8.1 up to build 10102.

Builds 10108 to 10131 use user account pictures that are somewhat reminiscent of the RTM ones, but the person in the picture is drawn with thinner lines and cropped more like the 8 and 8.1's.

By build 10134, these were replaced with their final variants.