Sorting in dhtmlxgrid

HI I am using dhtmlx grid and i have a data as following in one column,

4,57,000 (Note: this can be display only with red color and i have to consider it as (-) value at the time of sorting.)

Minus value is displayed in bracket. i want to perform sorting with bracket and number format.
I want to sort column based on Original value means my display value will be different and sort value will be different. which i have stored in some other html attribute , how to implement this.

Can you please suggest way.

Thanks & Regards,
Kausha Somaiya

Unfortunately the sorting function works only with the value of a cell: