12345

IMG12345 (originally called 'Lavender Dream' or 'D70_01451') is a default Picture Password setup image. It can be found in the Picture Password setup tutorial when you setting it for the first time. This image is built in the system file, so the only way to get it is to extract it from  with resource hacking software. It depicts several lavender flowers on a blurred grass background. The image itself has a non-standard size (1563x1200px) and most likely was never intended to be used as wallpaper (even though it was mentioned as 'Windows 8 secret wallpaper' on some Chinese Windows 8 forums back in 2012).

Since the picture password set up interface has not changed since Windows 8, the same picture can be found in Windows 8.1 and Windows 10 under the same conditions.

History
This picture was taken by Bernard Hymmen, a senior software engineer at Microsoft, on July 1st 2004 on a NIKON D70 camera. It's original size is 3008x2000px. The original image is available for download on Bernard's personal website

The picture used in Windows, comparing to the original one, was edited very much: it's stretched in some places (this can be noticed by the slight pixelation on the stem of the lower flower), has an odd overlay of itself (especially noticeable near the top flowers) and one of the flowers in the center is completely different. It probably was made to add more image depth.