Remove or change background border line color

Question

I have plotted an image with matplotlib and changed the background facecolor to gray, however there is this white border line around the background. I have tried to set the edgecolor to gray but still this white border line appears as shown in the image below. Is there any way to remove or change the border color? Below is my plotting code.

image

im = ax.imshow(im, cmap='gray', aspect="auto", vmin=vmin, vmax=vmax)
plt.tick_params(labelsize=6)
for label in  ax.get_xticklabels()+ax.get_yticklabels():
    label.set_fontsize(6)
fig.patch.set_facecolor("#C0C0C0")
fig.patch.set_edgecolor("#C0C0C0") 
plt.subplots_adjust(bottom=0.20,top=0.70,left=0.14,right=0.85)
plt.savefig(SavePath+'Image', facecolor=fig.get_facecolor(), transparent=True)