BAM sprites palette question

I was working with the frames and animations in the bam files which have alot of the character frames. These are mostly the BAMS in BG which begin with letter C (ie like CHFW2CA.BAM). The palettes on these are not the colors actually appearing in the game, and expect there is some conversion routine or formula which can change the color palette in various ways to reuse the same sprite but have different palette. Is this routine or formula documented anywhere on how to convert the frame colors to the actual game colors?