BootSkin Vista

BootSkin Vista, often shortened just to BootSkin, is the name of a program and its accompanying file format that allow for changes to the Windows boot screen. It succeeded the separate BootSkin XP, which is also sometimes called "BootSkin". BootSkin Vista files, which have the extension ".bootskin", are essentially PNG files with a small amount of separate metadata.

BootSkin Vista images may have a resolution of up to 1024x768 and 24-bit color. They are apparently generated on a server controlled by the program's authors, after a user uploads an image file. (This is probably an attempt to prevent people from making themes without paying.)

It should be noted that the BootSkin Vista program is also apparently able to accept plain image files, or at least JPEG files, as bootskins.

Some time around late 2016, BootSkin Vista was made free, something of an acknowledgment of the death of computer "skinning".

Structure
A BootSkin Vista file consists of:
 * The Magic number ("BSV" in ASCII)
 * The byte 0x01 (a version number?)
 * The title of the theme, encoded as a single byte indicating length followed by the string data
 * The name of the creator, encoded the same way
 * 4 bytes holding the length of the subsequent PNG file, little-endian
 * 4 zero bytes (maybe the length is 8 bits?)
 * Possibly another zero byte, probably alignment
 * A PNG holding a thumbnail? of the bootskin, 8-bit color, the horizontal dimension scaled to 400 pixels
 * A large amount of unknown data (taking most of the file)

Links

 * Homepage, combined with BootSkin XP
 * Skins on "Skinbase" (run by the same company that makes the software)
 * Combined Wikipedia page for both BootSkin versions