how to plot multiple images (separately) in one window

Hi everyone,

I have 2304x1024 matrix. I assume that each 3 rows of this matrix describe an image.(so I have 768 images and each image size = 3x1024 ).

Let's assume that imagesc(1:3, 1024 ) gives the first image, imagesc(4:6,1024) describes the second one and so on.

My code is here :

for ind=1:768
    start= (ind-1)*3+1;
    stop=ind*3;
    data = wholedata(start:stop,:);
   imagesc(data);     %%%%   or pcolor(data) or  %%%% I = mat2gray(data) and imshow(I)
end

When I use plot instead of imagesc I can plot multiple graphs in one figure :

figure
for ind=1:768
    start= (ind-1)*3+1;
    stop=ind*3;
    data = wholedata(start:stop,:);
   subplot(1,768,ind);
   plot(data);    
   hold on; 
end

I want to display images not graphs.

How to plot multiple images side by side in 1x768 format in a figure for example ? Or 32x24 format in a figure?

Thanks for your help.

[Image Analyst]

You aren't really going to display 768 images side by side across your display are you? Each image or plot would be only a pixel or two wide! Even if you did

subplot(28, 28, ind);

they'd still be pretty tiny!

If your screen is in a 9x16 aspect ratio, you can say (9*r) * (16*r) = 768, or r=2.3 and your subplot would look like

subplot(21, 37, ind);

[Adam Danz]

...or use tiledlayout('flow') and let Matlab arrange the plots for you. But even that has problems as I illustrated in my answer.

Answer 1

[KALYAN ACHARJYA]

"How to plot multiple images side by side in 1x768 format in a figure for example?"

I assumed that you want to divide the data into several subsections. Plots display data in the same axes, while imageshows or images can display with a concatenation (horizontal or vertical). Although you can arrange 2D individual planes in a 3D vector.

If plots multiple subdivisions from image or matrix data, in this case you can follow-

1st way: If you are looking for plot sections of the data matrix differently, you have follow the following ways, please set the subplot subwindows number accordingly

data=randi([0,255],[2304,1024]);
data_blocks=mat2cell(data,3*ones(1,768),1024);
for i=1:length(data_blocks)
  subplot(6,128,i), imagesc(data_blocks{i})
end 

2nd way: Directly access the indices using loop

data=randi([0,255],[2304,1024]);
for i=1:3:2304
  subplot(....),imagesc(data(i:i+2,:))
end 

Note: Please note on the large numbers of figures/plots

[Fatma Nur Disci]

Why did you say 6x128 for subplot matrix size ?

[KALYAN ACHARJYA]

"I have 2304x1024 matrix. I assume that each 3 rows of this matrix describe an image.(so I have 768 images and each image size = 3x1024 )."

You can set the tile layout (subplot) as per total window display, please do the changes as per requirements

6x128=768, see the subplot function

If you are using MATLAB version 2019b or latest, you can use title function

https://www.mathworks.com/help/matlab/ref/tiledlayout.html

[Fatma Nur Disci]

Thanks ! Yesterday I plotted all images just adding my code "subplot" before imagesc :

for ind=1:768

start= (ind-1)*3+1;

stop=ind*3;

data = wholedata(start:stop,:);

subplot(32,24,ind)

imagesc(data); %%%% or pcolor(data) or %%%% I = mat2gray(data) and imshow(I)

end

Answer 2

[Adam Danz]

768 independent axes on a figure will likely be problematicm, specifically the memory needed and the tiny size of each axis.

To demonstrate, the code below creates all 768 axes but I had to stop it after 551 axes because it was taking too long to add another axes (scroll down for more advice).

wholedata = rand(2304,1024); 
nImages = size(wholedata,1)/3; 
assert(mod(nImages,1)==0, 'The number of rows of data does not agree with number of images.')
data3D = reshape(wholedata',size(wholedata,2),3,[]); 

fig = figure();
tlo = tiledlayout(fig,'flow','TileSpacing','compact','Padding','compact');
for i = 1:size(data3D,3)
    ax = nexttile(tlo);
    imagesc(ax,data3D(:,:,i)')
end

Why not keep your image data together in its original 2304x1024 array?

figure()
imagesc(wholedata)

If you want to show the border between every 3rd row,

h=arrayfun(@(y)yline(y,'w-'),.5:3:size(data,1));

but that will add a lot of lines to the image.

[Fatma Nur Disci]

Thanks ! Yesterday I plotted all images using figure and subplot before imagesc :

for ind=1:768

start= (ind-1)*3+1;

stop=ind*3;

data = wholedata(start:stop,:);

subplot(32,24,ind)

imagesc(data); %%%% or pcolor(data) or %%%% I = mat2gray(data) and imshow(I)

end

[Adam Danz]

I'm curious to see a screenshot of this figure, if you're willing.