Function convert_index_palette_to_normal_bitmap 

pub fn convert_index_palette_to_normal_bitmap(
    pixel_data: &[u8],
    pixel_size: usize,
    palettes: &[u8],
    palette_format: PaletteFormat,
    width: usize,
    height: usize,
) -> Result<ImageData>

Available on crate feature image only.

Converts indexed pixel data and a palette into a standard image buffer.

pixel_size is expressed in bits per pixel for the indexed data.