h h u2212 360 if h lt 0 then h h 360 the first watermark in inserted into the rgb values in a conventional manner by modifying the i value of appropriate pixels so as to combine the watermark u03b4 values with hsi values this is indicated by equation 2 in fig4 next as indicated by equation 3 in fig4 the hsi values are converted to rgb values using a transform u201c t u201d the transform u201c t u201d can be conventional and it can for example be done as follows if i lt or 0 5 then m i i s a if h lt 60 then r m if h lt 120 then r m m u2212 m 120 u2212 h 60 if h lt 240 then r m if h lt 300 then r m m u2212 m h u2212 240 60 otherwise r m b if h lt 60 then g m m u2212 m h 60 if h lt 180 then g m if h lt 240 then g m m u2212 m 240 u2212 h u2014 60 otherwise g m c if h lt 120 then b m if h lt 180 then b m m u2212 m h u2212 120 60 if h lt 300 then b m otherwise b m m u2212 m 360 u2212 h 60 next the values which represent a second watermark are used to calculate a second set of rgb values designated rgb 2 in order to calculate rgb 2 the values.