SDL_ttf Shaded Rendering Palette

From the docWiki
(http://www.libsdl.org/cgi/docwiki.cgi/SDL_5fttf_2fFunctions_2fRender):
TTF_Render*_Shaded
"The 0 pixel value is background, while other pixels have varying
degrees of the foreground color from the background color."

Can I assume that the palette index values are a linear mapping from the
background to foreground here, where 0=bg … 255=fg?

I technically need a gray-scale map, and am using bg=(0,0,0) and
fg=(255,255,255), and am wondering if I can assume that the palette
index values will represent the varying value of the RGB components of
the pixels?

  • Silicon