Let us consider the following code (fs is sampling frequency)
function [] = AR_simulate(p,fs)
B = xlsread('data_generations1','A1','g8:g301');
for k = 1:1:p
[pxx,f] = pyulear(B,k);
plot(f,pxx);
F(k) = getframe;
end
movie(F,100);
end
which animates the power spectral density of a given B vector with different orders, namely from order k=1 to k=p.
Now I want to save each picture somewhere, but on each picture I would like to include the parameter k, for example at k=1 there was this picture, at k=2 there was different picture and so on.
This will put the title of each frame as k=1, k=2 etc. and will print each frame as an eps file to Frame1.eps, Frame2.eps, etc.
function []=AR_simulate(p,fs);
B=xlsread('data_generations1','A1','g8:g301');
for k=1:1:p
[pxx,f]=pyulear(B,k);
subplot(1,2,1)
plot(f,pxx);
F(k) = getframe;
title(['k=' num2str(k)])
subplot(1,2,2)
% 2nd plot
print('-depsc2',['Frame' num2str(k) '.eps')
end
movie(F,100);
end
You can also use text instead of title to place the text anywhere on the plot.
By default, getframe with zero input arguments captures a frame based on the current axis. If you want to capture a frame based on the figure, including a title and the axes ticks, you need to do getframe(gcf). Alternatively, use text as suggested by #David to place the label on the axes you capture.
Regarding saving of the images, you can use frame2im and imwrite, in the loop just after getframe:
im = frame2im(F);
imwrite(im,sprintf('im_k%03d.png',k))
Or to save the frames to a movie, use the VideoWriter class and call writeVideo on every iteration.
Related
I'm trying to digitize this image using MATLAB:
I have the following script:
%// Get data from plot
clear all; close all;
%// Input
fname = 'Fig15a.PNG';
xvec = [1e3:1:1e8];
yvec = [1e-4:1:1e-1];
xt = [1e3 1e4 1e5 1e6 1e7 1e8];
yt = [1e-4 1e-3 1e-2 1e-1];
%// Read and plot the image
im = imread(fname);
figure(1), clf
im = im(end:-1:1,:,:);
image(xvec,yvec,im)
axis xy;
grid on;
%// Set ticks
set(gca,'xtick',xt,'ytick',yt); %// Match tick marks
%// Collect data
[x,y] = ginput; %// Click on points, and then hit ENTER to finish
%// Plot collected data
hold on; plot(x,y,'r-o'); hold off;
%// Then save data as:
save Fig15a.mat x y
The script works fine
Is there a way I can change the x and y axes to a log scale ?
I have tried adding the following code in different places without luck:
%// Set Log scale on x and y axes
set(gca,'XScale','log','YScale','log');
Below's a proof of concept that should get you on the right track. I have replaced things in your original code with what I consider "good practices".
function q36470836
%% // Definitions:
FIG_NUM = 36470836;
%% // Inputs:
fname = 'http://i.stack.imgur.com/2as4t.png';
xt = logspace(3,8,6);
yt = logspace(-4,-1,4);
%% // Init
figure(FIG_NUM); clf
% Read and plot the image
im = imread(fname);
hIMG = imshow(im); axis image;
%// Set ticks
hDigitizer = axes('Color','none',...
'XLim',[xt(1) xt(end)],'YLim',[yt(1) yt(end)],...
'XScale','log','YScale','log',...
'Position',hIMG.Parent.Position .* [1 1 696/785 (609-64+1)/609]);
uistack(hDigitizer,'top'); %// May be required in some cases
grid on; hold on; grid minor;
%// Collect data:
[x,y] = ginput; %// Click on points, and then hit ENTER to finish
%// Plot collected data:
scatter(x,y,'o','MarkerEdgeColor','r');
%// Save data:
save Fig15a.mat x y
Here's an example of what it looks like:
Few notes:
xt, yt may be created in a cleaner fashion using logspace.
It is difficult (possibly impossible) to align the digitization grid with the image correctly, which would inevitably result in errors in your data. Though this can be helped in the following scenarios (for which you will require a vector graphics editor, such as the freeware InkScape):
If, by any chance, you got this image from a PDF file, where it appears as a vector image (you can test this by zooming in as much as you like without the chart becoming pixelated; this seems to be your case from the way the .png looks), you would be better off saving it as a vector image and then you have two options:
Exporting the image to a bitmap with a greatly increased resolution and then attempting the digitization procedure again.
Saving the vector image as .svg then opening the file using your favorite text editor and getting the exact coordinates of the points.
If the source image is a bitmap (as opposed to vector graphic), you can "trace the bitmap", thus converting it to vectoric, then #GOTO step 1.
This solution doesn't (currently) support resizing of the figure.
The magic numbers appearing in the Position setting are scaling factors explained in the image below (and also size(im) is [609 785 3]). These can technically be found using "primitive image processing" but in this case I just hard-coded them explicitly.
You can plot in double logarithmic scale with
loglog(x,y);
help loglog or the documentation give additional information.
For a single logarithmic scale use
semilogx(x,y);
semilogy(x,y);
I have the pixel locations of P points on a -constant- image, for T iterations of an algorithm, so locations = [T x 2*P] double.
Now I want to create an animation where it plots the image, then plots the points, pauses for N seconds and updates their location to the next step. I don't know if there is a standard way to follow. I think I need something like:
figure;
imshow(img);
hold on;
for t=1:T
anim = updatePlot(locations(t,:), anim); % ?
end
How can I implement this updatePlot function?
Thanks for any help!
You can do this a couple of different ways. The first way would be to give the plotted points a handle so that you can delete them before the next iteration:
figure
imshow(img);
hold on;
for t = 1:T
% delete the previous points plotted (skip t = 1 since they won't exist)
if t > 1
delete(hPoints);
end
hPoints = plot(xLocations(t,:),yLocations(t,:),'.');
getframe;
pause(N);
end
(I am not exactly sure how you parse your locations along each row to separate the x and y components, so I've just used xLocations and yLocations to represent those values.)
The second way would be to re-draw the entire image at each iteration:
figure
for t = 1:T
clf;
imshow(img);
hold on;
plot(xLocations(t,:),yLocations(t,:),'.');
getframe;
pause(N);
end
Note that imshow might have its own getframe effect so that you'll see the image flicker before plotting the points -- if that happens just switch from imshow to image.
I have a sequence of MATLAB figures which I want to convert to a video. The figures are composed of 2 subplots, such that each subplot contains an imshow with 2 different plots (red and green) overlayed on it, like the following:
How do I get an image of all the data contained inside each figure, so that next I can convert the sequence of images to a video with VideoWriter?
The key is:
im = frame2im(getframe(h));
Where h is the handle to your plot or axis
You can also pass an optional argument 'rect' to getframe to specify the area to capture.
Here is an example from the MathWorks on how to use getframe in a loop to record the frames. For more information type doc getframe
Z = peaks;
surf(Z)
axis tight manual
ax = gca;
ax.NextPlot = 'replaceChildren';
loops = 40;
F(loops) = struct('cdata',[],'colormap',[]);
for j = 1:loops
X = sin(j*pi/10)*Z;
surf(X,Z)
drawnow
F(j) = getframe(gcf);
end
% Play back the movie two times.
fig = figure;
movie(fig,F,2)
I have a set of polygon vertices in in X, Y matrices and their colors are in RGB values in another matrix C.
I then use fill() function to generate patch objects that is displayed in a Matlab figure.
I want to create a bmp object from this figure. What I mean by a bmp object is the x,y coordinates of the pixels and there RGB values.
If I use the print() function, with '-dbmp' and a file name, matlab can write the bmp to a file. But then I have to read the file with imread() to create the bmp object.
Is there a way to create the bmp object without writing and reading to from a file?
Becauswe I have to perform this operation many times and writing and reading to file is time consuming and will reduce the life time of my disk too I guess.
Edit: code after editing according to answer
N = 5;
Tri = 100;
res = 200; %200 pixles per inch
G = zeros(Tri,9,N);
X = 2*rand(Tri,3,N);
Y = 2*rand(Tri,3,N);
R = randi([0 255],Tri,N)/255;
G = randi([0 255],Tri,N)/255;
B = randi([0 255],Tri,N)/255;
for c1=1:N
G(:,1:3,c1)= X(:,:,c1);
G(:,4:6,c1)= Y(:,:,c1);
G(:,7,c1)= R(:,c1);
G(:,8,c1)= G(:,c1);
G(:,9,c1)= B(:,c1);
end
for c2=1:N;
h = figure('Visible','off');
set(h, 'PaperUnits', 'inches', 'PaperPosition', [0 0 400 400]/res);
for c3 =1:Tri
h1 = fill(G(c3,1:3,c2), G(c3,4:6,c2), [G(c3,7,c2) G(c3,8,c2) G(c3,9,c2)]);
set(h1,'EdgeColor','None');
hold on;
end
%print(h,'-dbmp',['-r' num2str(res)],['file' num2str(c2)]);
F = getframe(h);
[a, b] = frame2im(F);
Tmp_v1 = a;
Tmp_v1 = Tmp_v1(:);
Norm_v1(c2) = norm(single(Tmp_v1));
end
Thank you.
If you have the current figure open, you can try the getframe idiom. Once you have access to this, you can access the frame's image data by looking at the cdata field in the structure. After you have this, you can use the imwrite command from MATLAB's image processing toolbox (let's hope you have it...) to write the image to file.
Here's an example:
x = 1 : 5;
y = 1 : 5;
plot(x,y); %// Plot a line
h = getframe;
img = h.cdata;
imwrite(img, 'testFrame.bmp');
This should be able to grab what is inside the current figure and save it to file. In this case, this will be a straight line from (x,y) = (1,1) to (x,y) = (5,5), with a slope of 1. Bear in mind that this won't save the title of the graph or the axes. This will only grab what is rendered inside the frame.
Edit from comments
Now that I know what you're really after, you want to generate a bunch of random polygons, then extract just the core image, without any axes or tick marks and so on. You'll have to modify your for loop where you're creating the images so that you want the figure to fill the entire window without any gray padding You'll also want to turn off the axis too. Also, when you're generating each image, you'll need to turn off the ticks. This is done with a combination of not writing any tick labels, as well as setting the tick length to 0. In other words, you'll need to modify your code so that it looks like this. You'll see where I inserted code by seeing the %// NEW statements in your code:
for c2=1:N;
h = figure('Visible','off');
subplot('position', [0 0 1 1]); %// NEW
axis off; %// NEW
set(h, 'PaperUnits', 'inches', 'PaperPosition', [0 0 400 400]/res);
for c3 =1:Tri
h1 = fill(G(c3,1:3,c2), G(c3,4:6,c2), [G(c3,7,c2) G(c3,8,c2) G(c3,9,c2)]);
set(h1,'EdgeColor','None');
set(gca,'xcolor','w','ycolor','w','xtick',[],'ytick',[]) %// NEW
set(gca,'Ticklength',[0 0]); %// NEW
hold on;
end
%print(h,'-dbmp',['-r' num2str(res)],['file' num2str(c2)]);
F = getframe(h);
close all; %// NEW
[a, b] = frame2im(F);
a = imresize(a, [400 400], 'nearest'); %// NEW
Tmp_v1 = a;
Tmp_v1 = Tmp_v1(:);
Norm_v1(c2) = norm(single(Tmp_v1));
end
This will still show you the frames being popped up for each image you're creating, but you should be able to get just pure image data at this point. Note that the images are still coming out as a bit larger than 400 x 400. This is due to the fact that once we have removed the borders and the tick marks and so on, the figure will stretch to fill the entire figure. To get around this, I use imresize and shrink the images back down to 400 x 400 as per your desired size.
Also, take note that every time you generate a new image, a new figure is spawned. Every time you call getframe, the figure with this randomly generated polygon image pops up, and getframe takes a snapshot of that current frame. There isn't a way to prevent this from happening, as you won't be able to take a snapshot of that figure. One way to get around this would be to close the figure after you grab the image. You can do a close all; after each call to getframe. That way, only one figure gets shown at any one time, but this still won't prevent the figure from showing up.
If I do find a solution to this, I'll let you know!
I need something like this, but I have many matrices which describe 2D electric field change in process of time. So I would like matrices visualizations replaced each other, to get video
I want to give you a sample code to generate an animated gif from a sequence of plots. You can modify the plots to generate anything you like; e.g. the one in your link.
gifOutputName = 'sample.gif';
%# As an example, let us draw a 3-D plot
%# You can generalize it to anything you like
Z = peaks; surf(Z);
axis tight
set(gca,'nextplot','replacechildren');
for j = 1:20
surf(sin(2*pi*j/20)*Z,Z)
%# Grab the current frame
RGB = frame2im(getframe(gcf));
%# Reduce it to 256 colors since it's gonna be GIf image
[IND, map] = rgb2ind(RGB, 256);
if j == 1 % Vreate in the first step
%# 'LoopCount' indicates how many times the animation will play,
%# Inf states infinity. Refer to "GIF-Specific Parameters" in the
%# documentation.
imwrite(IND, map, gifOutputName, 'gif', 'LoopCount', Inf);
else %# Otherwise, append it to the previous
imwrite(IND, map, gifOutputName, 'gif', 'WriteMode', 'append');
end
end
close %# Close the figure
(source: ismailari.com)