Save OR open figure with transparent background

Hello,

I need to save my pie charts without white background behind it (transparent), I was searched dozens of webpages and tried:

set(gcf, 'color', 'none');
% and
set(gca 'color', 'none');

But not works for me. I even used export_fig from FEX in this syntax:

export_fig (ax, ['filename' num2str(k) '.png']);

But I got this error:

Unrecognized function or variable 'using_hg2'.
Error in export_fig>parse_args (line 1391)
        options.aa_factor = 1 + 2 * (~(using_hg2(fig) && isAA) |
        (options.renderer == 3));
Error in export_fig (line 330)
    [fig, options] = parse_args(nargout, fig, varargin{:});

Here is all my code,

clf
f = figure();
ax = axes();
p = pie(ax, ones(1,5)); 
t = p(2:2:end); 
p = p(1:2:end); 
delete(t)
s = {'CC', 'ME', 'NU', 'BI', 'IA'};
for k=1:size(davar1, 1)
    for i=1:numel(s)
        switch davar1(k,:).([s{i} '_CHECK']) % I even tried insert (j) here and do it in the for loop but error says Index exceeds the number of array elements (2).
            case 'New York'
                p(i).FaceColor = 'g';
            case 'California'
                p(i).FaceColor = 'y';
            case 'Illinois'
                p(i).FaceColor = 'r';
            case 'Texas '
                p(i).FaceColor = 'k';
            case 'Ohio'
                p(i).FaceColor = 'b';
            case 'North Carolina'
                p(i).FaceColor = 'c';
            case 'Tennessee'
                p(i).FaceColor = 'w';
        end
    end
    exportgraphics(ax, ['filename' num2str(k) '.png']);
end

I saw some people say save figure as .png then go to windows Microsoft Office PowerPoint and make your picture background transparent but I have over 200 images and it would be awesome if Matlab can do it. Please guid me how I can export my figure in transparent mode.

Thank you all

Answer 1

[Ameer Hamza]

Call export_fig with additional inputs

export_fig('filename', '-dpng', '-transparent', '-r300'); % -r300 is the PPI value, default resolution is low

[BN]

Thank you so much again.

[Ameer Hamza]

Glad to be of help.

[John Mungall]

This was remarkably helpful. I am very grateful.

In my case, the last three lines of my test were:

scatter(x,y,sz,c,'filled');

filename = 'scattertransparent2';

export_fig(filename, '-dpng', '-transparent', '-r300'); % -r300 ...

After some "jiggling" with Word Size and Position, this let me produce a scatter plot overylying a jpg map with the map being situated nicely inside the plot axes. What a relief...

[Yuan Zhang]

Thanks Ameer, your code is really helpful!