It only supports YUV112 (color component sampling 1:1:2)
It doesn't support 'Progressive encoding' Supports 16 color, 256 color and 24bit Color BMPs cap BIOS file using iCHLogo and then update target system BIOS using iFlashV tool. You can change the splash screen to the image of your choice by using iCHLogo and iFlashV tools. To determine which BIOS core is used on your Intel NUC reference this article.
If your NUC has Visual BIOS Core, you need to follow this article. This article is for for Intel® NUCs with the Aptio V BIOS Core. Intel® NUCs include a default splash screen image that displays during startup:
