I tried other format like png and pdf using following command in GNUPLOT:
set term png size H,W
where H, W were resolution of the image generated.
But they were not helping in the start as the print contained distortions. It turned out the problem was with the dpi.
So after some research I found out following link:
I found the following commands using the above link:
set terminal postscript enhanced color
set output '| ps2pdf - plot.pdf'
It converts the ps file to pdf with the same result in pdf as was in the ps file.
And it was taking only 3seconds for the printer to read.
I hope it would help someone in future. Regards, Hammad