The different results of functions getframe and imread

Hi everybody

I have simple function:

=================================================

function getframe_inmread

for i = 1:200
 for j = 1:300 
  latmap(i,j) = 10 + (j - 1) * 0.1;
  lonmap(i,j) = 10 + (i - 1) * 0.1;
 end;
end
A(1:200, 1:300) = 1;
A(50:100, 100:200) = 2;
f1 = figure; 
axesm gortho
surfm(latmap,lonmap,A);

% ------------ version 1 - getframe

pos = get(gcf,'Position');

Bgf = getframe(gcf);
sgf = size(Bgf.cdata)

% ------------ version 2 - imread

fl_pic = 'tmp_frim';
% print('-f1', '-dpng',fl_pic);
print('-f1', '-dbmp',fl_pic);
close(f1);
% af = imread([fl_pic '.png']);
af = imread([fl_pic '.bmp']);
saf = size(af)

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Obtain arrays (colors) of different dimension.

>>sgf =
   420   560     3

>>saf =
         901        1201           3

I need to getframe gave the same array as imread, because upon application of map I should take the second map of imread.

Any help on the topic would be greatly appreciated.

Thanks

[Jan]

Please apply a proper code formatting as explained in the "Markup help" link. And please be so kind and explain, why the formatting of the code is so hard for beginners.

Answer 1

[Jan]

The function getframe creates an exact pixel copy of the contents of the window. In opposite to this print performs some rescaling, e.g. if you export the figure contents with a different resolution. But even for -r0, the original screen resolution, the output is not exact. E.g. UICONTROLs are rendered differently and embedded as raster images.

In consequence IMREAD(PRINT) and GETFRAME will not produce the 100% equal results.