How to hold previous figures when using imagesc?

Question

Raju Kumar 2023-5-23

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1971284-how-to-hold-previous-figures-when-using-imagesc

编辑： Image Analyst 2023-5-29

I have many datasets (two of them provided below) to be plotted on a 256x256 pixels image. The first column in each dataset is the pixel index and the second column -intensity. When I am plotting this using 'imagesc', the figure does not update/hold rather only the last dataset gets plotted. Can anyone suggest a code or modify my code below to have all the datasets plotted on a single plot? Many thanks in advance.

Set 1:

26319 2

25806 6

26322 2

25811 7

25295 2

25298 4

26320 8

26321 8

25551 19

25554 18

26063 19

26066 18

25296 9

25297 9

26064 60

26065 61

25552 59

25553 62

25807 49

25810 58

25808 390

25809 378

set 2:

47291 31

47290 7

46269 37

46012 10

47033 34

46010 22

47037 39

47036 129

46011 40

46265 42

46525 94

46268 133

46777 95

46781 95

46267 165

46266 129

46523 238

46522 194

46779 228

46778 195

47035 172

47034 136

46524 194

46521 96

46780 212

The code:

for loop to access each dataset..
    H11 = zeros(256,256);
    H11(column 1) = column 2;
    figure(1)
    ax = gca;
    imagesc(H11); f1=colorbar; ylabel(f1, 'TOT'); hold(ax, 'on');
    colormap(ax, 'jet');
    colorbar(ax);
    hold(ax, 'on');
    xlabel(ax, 'Horizontal pixels');
    ylabel(ax, 'Vertical pixels');
end

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Answer 1

Saffan 2023-5-29

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https://ww2.mathworks.cn/matlabcentral/answers/1971284-how-to-hold-previous-figures-when-using-imagesc#answer_1246554

在 MATLAB Online 中打开

Hi Raju,

imagesc command creates a new plot every time it is called and hence image is overwritten by the last dataset and hold does not work as expected. You need to create a running sum of all the datasets in each iteration and then plot the sum after the loop.

Here is an example code snippet:

H_sum = zeros(256,256);
for loop to access each dataset..
    H11 = zeros(256,256);
    H11(column 1) = column 2;
    % creating a running sum
    H_sum = H_sum + H11; 
end
figure(1)
ax = gca;
imagesc(H_sum);
f1=colorbar; 
ylabel(f1, 'TOT'); hold(ax, 'on');
colormap(ax, 'jet');
colorbar(ax);
hold(ax, 'on');
xlabel(ax, 'Horizontal pixels');
ylabel(ax, 'Vertical pixels');