Apologies if this is a dupe, I've been searching for over an hour but the search terms are all really broad and I just keep getting the same results. Also I'm fairly new to matlab so apologies for any misunderstandings.
Anywho, I have a matlab program which needs to frequently save an image generated from a matrix, but I just can't figure out how to do that without displaying it first. Basically I'm caught in between two functions, image and imwrite, both only do half of what I want.
image is able to take my matrix and create the desired output, but it just displays it to a figure window
imwrite is able to save an image to a file without displaying it, but the image is completely wrong and I can't find any parameters that would fix it.
Other questions I've seen deal with using imread and managing figures and stuff, but I'm just doing (for example)
matrix = rand(20);
colormap(winter);
image(matrix, 'CDataMapping', 'scaled');
or
matrix = rand(20);
imwrite(matrix, winter(256), 'filename.png');
Is there some way to call the image function such that it doesn't display a figure window and then gets saved to a file? Something analogous to calling imshow and then savefig in matplotlib.
Just do this:
matrix = rand(20);
f = figure('visible', 'off');
colormap(winter);
image(matrix, 'CDataMapping', 'scaled');
print(f, '-dpng', 'filename.png');
I'm using the print function in MATLAB to write images of plots, something like that
print(figure(1),'-dpng','-r300',filename);
But apparently the images are not overwritten, and the original images stay. I was using saveas before, which seems to overwrite the images, but print gives me more output options. Any ideas?
UPDATE: I ended up deleting the files before the printing with a different function.
You can use this:
im = frame2im(getframe(gcf,rec)); %Grabs image of plot as an image
imsave(im, filename); %save image
That syntax may not be 100%, its a while since I've used it.
Also be aware that this isn't perfect - I remember having issues with it grabbing a grey border around the edge of the plot. Also, I think the image may be based on a matlab screenshot.... just something to be aware of
Saving figures in matlab is rather troublesome, especially if the saved image should look like the original figure.
For myself i found the solution in using export_fig.
It's one of the most downloaded fileexchange files - maybe you should give it a try:
http://www.mathworks.de/matlabcentral/fileexchange/23629-export-fig
A small introduction to export_fig can be found at:
https://github.com/ojwoodford/export_fig/blob/master/README.md
i have a code which gives several images as ouput and i want to set all these images in particular axes in GUI in matlab. I'm trying to make a GUI of the code.
For eg.
figure,imshow(s1);
figure,imshow(s2);
figure,imshow(s2&s1);
and i want to set the output image of first command in, say axes3, output image of second command in axes4 and similarly last output image in axes5.
Although i know i need to use
set(handles.axes...)
command but i don't know the exact syntax on how to make the image be shown in particular axes.
Please give explain on how to make this happen with any suitable example. Thanks in advance.
One line solution (for each image) is to set the axis as the parent of the image within the imshow command;
imshow(image_Data,'Parent',handles.axes1)
There should be no need to open the additional figure windows ( assuming the axes are with the gui...)
So specifically for the question above:
imshow(s1,'Parent',handles.axes3);
imshow(s2,'Parent',handles.axes4);
imshow(s2&s1,'Parent',handles.axes5);
First you should create an axes box in your gui, then in tag section get a name i.e. (original) and finaly in editor when you want to use it code something like this
A = imread (Path);
axes(handles.original);
imshow(A);
I hope to help you...
I am trying to plot a time series (a seismograph) with a corresponding spectrogram in R.
Since I would like to compare the time series with the spectrogram, the X axis labels on the time series need to line up with the X axis labels on the spectrogram. However, I'm having a lot of trouble with this. The best I've been able to do so far is use
par(mar=c(0,10,0,8))
and try to manually force the spectrogram labels to line up with the time series labels by tweaking the spectrogram margin. Of course this is only approximate and they still do not line up perfectly. Is there a way to make the axes generated by the code below match up with each other?
par(mfcol=c(2,1))
plot(seq_len(1000)*0.01, sin(2*pi*seq_len(1000)*0.01), type="l",xlab="Time",
ylab="Amplitude", main="Time Series", xlim=c(1,10))
image(seq_len(1000)*0.01,seq_len(100)*0.1,array(runif(1000000),dim=c(1000,100)),
xlab="Time", ylab="Frequency", main="Spectrogram", xlim=c(1,10))
Thanks in advance!
This seems to work:
par(mfcol=c(2,1))
plot(seq_len(1000)*0.01, sin(2*pi*seq_len(1000)*0.01), type="l", xaxs="i")
image(seq_len(1000)*0.01,seq_len(100)*0.1,array(runif(1000000),dim=c(1000,100)),
xlab="Time", ylab="Frequency", main="Spectrogram")
Just drop the xlim= arguments and use xaxs="i" in the plot() function to match the default for image().
You can either add xaxs='i' to the call to plot (this removes the extra padding so it lines up with the image plot), or you could use par('usr') after the 1st plot to see what the x limits are and use those values in the xlim call in image.
It turns out that this is way easier than it looked initially. The secret is to make a "dummy plot" and then add the image to the plot. So here's how the new, working code looks:
par(mfcol=c(2,1))
plot(seq_len(1000)*0.01, sin(2*pi*seq_len(1000)*0.01),
type="l",xlab="Time",ylab="Amplitude", main="Time Series")
plot(c(0,10), c(0,10), type="n") #Dummy plot with axis limits for our spectrogram
image(seq_len(1000)*0.01,seq_len(100)*0.1,array(runif(1000000),dim=c(1000,100)),
xlab="Time", ylab="Frequency", main="Spectrogram",add=TRUE)
Similar, but conversely, to Greg Snow's answer, you could add xaxs='r' to the call to image as follows:
par(mar=c(0,10,0,8))
par(mfcol=c(2,1))
plot(seq_len(1000)*0.01, sin(2*pi*seq_len(1000)*0.01), type="l",xlab="Time",
ylab="Amplitude", main="Time Series", xlim=c(1,10))
image(seq_len(1000)*0.01,seq_len(100)*0.1,array(runif(1000000),dim=c(1000,100)),
xlab="Time", ylab="Frequency", main="Spectrogram", xlim=c(1,10), xaxs="r")
Don't forget to save your par() setting first.
(maybe I should have put that above)
I'm facing a problem when displaying an image and using hold on to then plot hough lines on top of it. I want to store this image in a variable including lines on it and use it further. How can I do that?
You can use the copyobj for this. Or the getframe function if you're making a movie.