Translations:Booting Into PC-BSD®/9.2/46/en
From PC-BSD Wiki
If you would like to change the image in the graphical boot loader, create aimage file. It is important that the file is saved in .pcx format as that is the only image format that the boot loader understands. Additionally, the image must be 640 x 480 pixels and 16 colors. The RGB colors that will be available in the menu text will be taken from the image's palette.
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