Bruce how are the volume bars histograms calculated ? 

I mean what gives green colour to volume bar and what gives red colour to volume bars ??

It is based on the net change in price (current price or close versus previous close). If the net change is positive, the color is green, otherwise the color is red.

Ok good, now is there a pcf that u can write where the volume colour is based on open and close of price bars ?

so current price or close is greater then open then it gives volume bar as green and current price close is less then open then volume bar is red  ?

thanks 

You could plot three Custom PCF Indicators and overlay them into the same pane and scale as each other.

The first would be the base color (maybe yellow or white?):

V

The second would be in green.

IIF(C > O, V, 1 / 0)

And the third would be in red.

IIF(C < O, V, 1 / 0)

Alternately you could use green or red for the first formula (whichever one you wanted to use for a true doji) and then use just one of the second or third formulas (the opposite color versus what you used for the first formual).

Perfect Bruce , 

thankyou :)

You're welcome.