Removing the grey margin of a plot

Hi I'm doing an image analysis using matlab. I have a figure that I need to remove the grey margin and axes while keeping the original white plot area size constant and then save it as png. You can see the saved original png which I need to remove the axes and the margin but keeping the plot area size constant. p.s. I'm using R2017a version.

Answer 1

[KSSV]

plot(peaks)
title('Plot of Peaks Function')
axis off
ax = gca;
outerpos = ax.OuterPosition;
ti = ax.TightInset; 
left = outerpos(1) + ti(1);
bottom = outerpos(2) + ti(2);
ax_width = outerpos(3) - ti(1) - ti(3);
ax_height = outerpos(4) - ti(2) - ti(4);
ax.Position = [left bottom ax_width ax_height];

Now save them using saveas

[hamed]

I faced another problem. This code still keeps the margin due to x and y axis even though I removed the axis. You can see that in the attached figure. How to remove that white margin too?

Answer 2

[Walter Roberson]

img = imread('fig2.png');
im2 = img;
mask = repmat(all(im2 < 240,3),1,1,3);
im2(mask) = 255;

[hamed]

Thanks.