The absolute minimum value, of the function \( f(x)=\left|x^{2}-x+1\right|+\left[\,x^{2}-x+1\,\right] \), where \([\,t\,]\) denotes the greatest integer function, in the interval \([ -1,\, 2 ]\), is:
\( \frac{1}{4} \)
\( \frac{3}{4} \)
\( \frac{3}{2} \)
\( \frac{5}{4} \)