Getframe function problem: Captured Image will not re-display at same size

2015 10 3
2 个回答
更新时间：2018 8 8
5 次查看（30 天）

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goal: I want to be able to capture the color by pixel location data (C-data?) of any current figure, scramble the locations of any black pixels in it, and then re-display the figure in scrambled form.
problem: After scrambling the figure and re-displaying it, it is now a different size than the old figure. I want it to be the same size as the unscrambled version.
I think the problem lies in how I am capturing and then displaying the image. This is how I am doing that: (after creating a current figure). Attached is a screenshot of the problem for clarity. I am running 2015a.
function[CurrentFigureData, CurrentFigureMap]= WriteCF2Workspace()
F = getframe(gcf);
[CurrentFigureData, CurrentFigureMap] = frame2im(F);
end
figure(2);ScreenDims = get(0, 'ScreenSize'); set(2,'position',ScreenDims, 'menubar','none'); image(CurrentFigureData); axis off;

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Image Analyst
Image Analyst 2015-10-3
Why not just use an axes control with an image in it, instead of trying to do the whole figure?
Michael Bronstein
Michael Bronstein 2015-10-3
Thanks for the idea. Could you explain how making that change would solve the problem? -Michael

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回答（2 个）

Walter Roberson
Walter Roberson 2015-10-3

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curfig = gcf;
curfig_units = get(curfig, 'units');
curfig_size = get(curfig, 'Position');
curimage_h = findall(curfig, 'type', image');
curax = ancestor(curimage_h, 'axes');
fig2 = figure('Units', curfig_units, 'Position', curfig_size);
ax2 = copyobj(curfig_ax, fig2);
image2 = copyobj(curimage_h, ax2);

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Michael Bronstein
Michael Bronstein 2015-10-3
Thanks for the help so far Walter! This looks promising, but I have one question. When I run that code I get the following error: Error using copyobj Copyobj cannot create a copy of an invalid handle.
Error in Untitled (line 7) ax2 = copyobj(curfig_ax, fig2);
Do you know why that might be?
Walter Roberson
Walter Roberson 2015-10-4
curfig = gcf;
curfig_units = get(curfig, 'units');
curfig_size = get(curfig, 'Position');
curimage_h = findall(curfig, 'type', image');
curax = ancestor(curimage_h, 'axes');
fig2 = figure('Units', curfig_units, 'Position', curfig_size);
ax2 = copyobj(curax, fig2);
image2 = copyobj(curimage_h, ax2);
Michael Bronstein
Michael Bronstein 2015-10-4
Unfortunately, this solution does not work. When I insert the scrambled image on the figure that this script creates it does not align with the original.
yuval
yuval 2018-8-8
Hi Michael, I'm facing similar difficulty, were you able to figure it out?
Here is the code I was working on at the time:
function[TransformMe,CurrentFigureData,CurrentFigureMap] = MaskFromCF() %iterate over each dimension from 1:dimsize. Find all indicies where all 3 %= 0. Do it so that you only check dim 2 if dim 1 was 0, and only dim 3 if %dim 2 was 0. Record those indicies, and you will have black pixels! %note that white is 255, 255,255 RGB
%create workspace var with image data [CurrentFigureData, CurrentFigureMap] = WriteCF2Workspace;
%now modify it to make mask, start by finding all black pixels (works only for black text on white) SizeOfData = size(CurrentFigureData); display(SizeOfData(1)) LocationsOfBlack = []; for i = 1:SizeOfData(1) for j = 1:SizeOfData(2) if CurrentFigureData(i,j,1) == 0 && CurrentFigureData(i,j,2) == 0 && CurrentFigureData(i,j,3) == 0 LocationsOfBlack{1,end+1} = {i,j}; end end end %now that you found all black pixels, find the furthest left/right values %that are black. You will scramble the pixels between these values.
%%%%you can mod these parameters to make it look only in a certain %%%%space.%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% furthestX = -inf; smallestX = inf; furthestY = -inf; smallestY = inf;
%the parts after the && signs in this for loop specify screen locations to search in. Remove to search whole screen. %NOTE THAT X AND Y HERE CORRESPOND TO THE OPPOSITE SCREEN Dimension (restricting X effects Y range when shown etc.) %Also note that low numbers correspond to the top of the screen and higher %ones to the bottom of the screen for i = 1:length(LocationsOfBlack) testx = cell2mat(LocationsOfBlack{i}(1)); testy = cell2mat(LocationsOfBlack{i}(2)); if testy > 270 && testy < 1022 && testx > 80 && testx < 270 %restricts screen scan area for mask (by limiting scan for black). Change numbers to alter screen scan area. Go = 1; else Go = 0; end if Go == 1 if cell2mat(LocationsOfBlack{i}(1)) > furthestX furthestX = cell2mat(LocationsOfBlack{i}(1)); end if cell2mat(LocationsOfBlack{i}(1)) < smallestX smallestX = cell2mat(LocationsOfBlack{i}(1)); end if cell2mat(LocationsOfBlack{i}(2)) > furthestY furthestY = cell2mat(LocationsOfBlack{i}(2)); end if cell2mat(LocationsOfBlack{i}(2)) < smallestY smallestY = cell2mat(LocationsOfBlack{i}(2)); end end end %end of section where you can mod parameters to impact search field %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% Xdiff = furthestX-smallestX; Ydiff = furthestY-smallestY;
%Move around the pixels ShuffleX = randperm(Xdiff+1)+smallestX; %start shuffling from smallest to largest X. ShuffleY = randperm(Ydiff+1)+smallestY; %you now have the indexes you need to shuffle, now shuffle them in %CurrentFigureData TransformMe = CurrentFigureData; for i = smallestX:furthestX for j = smallestY:furthestY k = i-(smallestX-1); l = j-(smallestY-1); TransformMe(i,j,:) = CurrentFigureData(ShuffleX(k),ShuffleY(l),:); end end
And the other function:
function[CurrentFigureData, CurrentFigureMap]= WriteCF2Workspace() F = getframe(gca); [CurrentFigureData, CurrentFigureMap] = frame2im(F); end
I think it did end up working, but unfortunately I can't test it atm because I don't have access to my normal pc. Hope the code helps. Good luck!

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yuval
yuval 2018-8-8

0 个投票

Replace gcf with gca, i.e.,
F = getframe(gca); [CurrentFigureData, CurrentFigureMap] = frame2im(F);

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