I want to display a video of my choice in an user interface using GUIDE. To do that I have a pushbutton to choose the video and an axis to display it.
According to Matlab I don't have mistakes and I looked around to find solutions without success...
% --- Executes on button press in ouvrir.
function ouvrir_Callback(hObject, eventdata, handles)
% hObject handle to ouvrir (see GCBO)
% eventdata reserved - to be defined in a future version of MATLAB
% handles structure with handles and user data (see GUIDATA
% Ask the user what video he wants to load
[filename, pathname] = uigetfile({'*.avi'},'File Selector');
fullPathname = strcat(pathname, filename);
disp(fullPathname);
set(handles.text2, 'String', filename);
%display the video in the axis
video = vision.VideoFileReader(fullPathname);
while ~isDone(video)
frame = step(video);
showFrameOnAxis(handles.axes1,frame);
end
When I launch my programm, i can load the file and it displays it well but the axis just diseapear...
If you could help me a litle it would be great !
Sincerely yours.
edit : Do you recommend me to create my own UI ?
You're try this. It's show and play video in axes.
videoFReader = vision.VideoFileReader(filename);
while ~isDone(videoFReader)
frame = step(videoFReader);
showFrameOnAxis(handles.axes,frame);
end
Related
For a project, i'm trying to create a video then adding some images into it, using Scilab SIVP with the function avifile() to create a video and addframe() to add an image.
I tested the stantard scilab example :
im = imread('lena.png');
n = avifile('lena.avi', [300;300], 30);
for ii=1:200
ims = im(ii:512-ii, ii:512-ii, :);
addframe(n, ims);
end
aviclose(n);
The error that i get is that the image don't have the adequate size (the video is created but it has 0 ko).
Can you tell me how to fix that error or how should i choose the right size please?
Thanks!
I have a double 2D image that I want to use in my UI that I made with guide. I have a axis handle which I want to draw it to. I tried this with no success, my image is all blue.
function ComputeMap_Callback(hObject, eventdata, handles)
% hObject handle to ComputeMap (see GCBO)
% eventdata reserved - to be defined in a future version of MATLAB
% handles structure with handles and user data (see GUIDATA)
global healthyImage;
global sickImage;
global tumorMapImage;
global costFunction;
if(get(handles.radiobuttonMSE,'Value') == get(hObject,'Max'))
costFunction = 0;
else
costFunction = 1;
end
disp(costFunction);
tumorMapImage = mexFunction(im2double(sickImage),im2double(healthyImage),get(handles.blockSize,'Value'),get(handles.windowSize,'value'), costFunction);
image(tumorMapImage,'parent',handles.sImageGUI);
This mexFunction returns a double 2D image. If I just call this function without matlab and imShow (resultImage); I get the right result. So I believe it has something to do with the colormapping of the double and the fact that the image is not 3D but 2D. But I am 0 familiar with gui in matlab to be sure what to do. I've done some more researches and I think my problem might be related to the AlphaData property, but I don't know what to do with that.
your image values must be in range [0, 1] in order to be plotted properly by the image function.
imshow works because it first looks at the min and max value in your image and then scales values to match this range. or so. (maybe it works differently internally, but whatever..)
I'm currently creating my figures in matlab to embed themvia latex into a pdf for later printing. I save the figures and save them via the script export_fig! Now I wonder which is the best way to go:
Which size of the matlab figure window to chose
Which -m option to take for the script? It will change the resolution and the size of the image...
I'm wondering about those points in regards to the following two points:
When chosing the figure-size bigger, there are more tickmarks shown and the single point markers are better visible
When using a small figure and using a big -m option, I still have only some tickmarks
When I generate a image which is quite huge (e.g. resolution 300 and still 2000*2000px) and than embed it into the document: Does this than look ugly? Will this be embedded in a nice scaling mode or is it the same ugliness as if you upload a 1000*1000px image onto a homepage and embed it via the widht and height tags in html -> the browser displays it quite ugly because the browser doesn't do a real resize. So it looks unsharp and ugly.
Thanks in advance!
The MATLAB plots are internally described as vector graphics, and PDF files are also described using vector graphics. Rendering the plot to a raster format is a bad idea, because you end up having to choose resolution and end up with bigger files.
Just save the plot to EPS format, which can be directly embedded into a PDF file using latex. I usually save my MATLAB plots for publication using:
saveas(gcf, 'plot.eps', 'epsc');
and embed them directly into my latex file using:
\includegraphics[width=0.7\linewidth]{plot.eps}
Then, you only need to choose the proportion of the line the image is to take (in this case, 70%).
Edit: IrfanView and others (XnView) don't display EPS very well. You can open them in Adobe Illustrator to get a better preview of what it looks like. I always insert my plots this way and they always look exactly the same in the PDF as in MATLAB.
One bonus you also get with EPS is that you can actually specify a font size so that the text is readable even when you resize the image in the document.
As for the number of ticks, you can look at the axes properties in the MATLAB documentation. In particular, the XTick and YTick properties are very useful manually controlling how many ticks appear no matter what the window resolution is.
Edit (again): If you render the image to a raster format (such as PNG), it is preferable to choose the exact same resolution as the one used in the document. Rendering a large image (by using a big window size) and making it small in the PDF will yield bad results mainly because the size of the text will scale directly with the size of the image. Rendering a small image will obviously make for a very bad effect because of stretching.
That is why you should use a vector image format. However, the default MATLAB settings for figures produce some of the same problems as raster images: text size is not specified as a font size and the number of ticks varies with the window size.
To produce optimal plots in the final render, follow the given steps:
Set the figure's font size to a decent setting (e.g. 11pt)
Render the plot
Decide on number of ticks to get a good effect and set the ticks manually
Render the image to color EPS
In MATLAB code, this should look somewhat like the following:
function [] = nice_figure ( render )
%
% invisible figure, good for batch renders.
f = figure('Visible', 'Off');
% make plots look nice in output PDF.
set(f, ...
'DefaultAxesFontSize', 11, ...
'DefaultAxesLineWidth', 0.7, ...
'DefaultLineLineWidth', 0.8, ...
'DefaultPatchLineWidth', 0.7);
% actual plot to render.
a = axes('Parent', f);
% show whatever it is we need to show.
render(a);
% save file.
saveas(f, 'plot.eps', 'epsc');
% collect garbarge.
close(f);
end
Then, you can draw some fancy plot using:
function [] = some_line_plot ( a )
%
% render data.
x = -3 : 0.001 : +3;
y = expm1(x) - x - x.^2;
plot(a, x, y, 'g:');
title('f(x)=e^x-1-x-x^2');
xlabel('x');
ylabel('f(x)');
% force use of 'n' ticks.
n = 5;
xlimit = get(a, 'XLim');
ylimit = get(a, 'YLim');
xticks = linspace(xlimit(1), xlimit(2), n);
yticks = linspace(ylimit(1), ylimit(2), n);
set(a, 'XTick', xticks);
set(a, 'YTick', yticks);
end
And render the final output using:
nice_figure(#some_line_plot);
With such code, you don't need to worry about the window size at all. Notice that I haven't even showed the window for you to play with its size. Using this code, I always get beautiful output and small EPS and PDF file sizes (much smaller than when using PNG).
The only thing this solution does not address is adding more ticks when the plot is made larger in the latex code, but that can't be done anyways.
I am making a GUI for a program I have created, where I need to be able to change the position of a load along a beam. I have set up the axes and the slider properly, but I am unsure how to get the axes to update, as I can't find any examples that show how to do this on the internet.
At present, as I move the load, the position updates properly, but the old position stays on screen as well, which is quite annoying.
Can anyone recommend any good examples that show how to do this, or does anyone have a suggestion of how to go about refreshing the axes?
Here is the slider callback (I haven't included the create_fcn function). Also, theres a lot of comments in the code, as I used the Guide function to make the GUI.
Please note that the input to slider is a proportion of the overall beam length (as a decimal).
function PointLoadxx1posslider_Callback(hObject, eventdata, handles)
% hObject handle to PointLoadxx1posslider (see GCBO)
% eventdata reserved - to be defined in a future version of MATLAB
% handles structure with handles and user data (see GUIDATA)
% Hints: get(hObject,'Value') returns position of slider
% get(hObject,'Min') and get(hObject,'Max') to determine range of slider
PLxx1pos = get(handles.PointLoadxx1posslider,'value');
set(handles.PLxx1posedit, 'String', num2str(PLxx1pos));
l = 3000; % This is the Length of the beam
zpl1 = get(handles.PointLoadxx1posslider,'value')*l;
% Multiplies the position decimal by the overall length
LoadPlotter(hObject,zpl1,handles) % Sends the command to the plot plot function
guidata(hObject,handles);
function LoadPlotter(hObject,zpl1,handles)
% The following draws the beam supports as lines
SH = l/20; %Height of supports
line([0 l], [SH/2 SH/2])
line([-SH/2 SH/2], [0 0])
line([-SH/2 0], [0 SH/2])
line([0 SH/2], [SH/2 0])
line([l-SH/2 l+SH/2], [0 0])
line([l-SH/2 l], [0 SH/2])
line([l l+SH/2], [SH/2 0])
xlim([ -100 l+200])
ylim([-l/2 l/2])
%Draw Load position
% zpl1 = get(handles.PointLoadxx1posslider,'value')*l;
% zpl1 = 0.5*l;
zpl2 = 0.2*l;
PL1 = 50;
%This is the value of the point load applied to the beam, which will
be an input from another slider
PL1Draw = line([zpl1 zpl1],[SH/2 PL1*10]);
% refresh(handles.axes1);
guidata(hObject,handles);
Obviously, I would like to keep the other lines drawn, but change PL1Draw as the slider is moved. Please can you explain what I am supposed to tag to do this?
Many thanks in advance.
James
I assume that you have plotted a beam, which is supposed to bend as you change the slider value. Since you are able to plot the new position into the axes, I assume that you know how to write callbacks. I further assume that there are parts of the plot that should stay the same, and parts that should change.
To change the parts that need changing, the easiest method is just to delete them and then to redraw. In order to delete specific items from a plot, it's best to tag them. Thus, your plotting would go like this
%# remove the old position
%# find the handle to the old position by searching among all the handles of
%# the graphics objects that have been plotted into the axes
oldPosHandle = findall(handles.axes1,'Tag','position');
delete(oldPosHandle);
%# plot new position
PL1Draw = line([zpl1 zpl1],[SH/2 PL1*10]);
%# add the tag so that you can find it if you want to delete it
set(PL1Draw,'Tag','position');
Note 1
To make the GUI respond faster (if needed), do not delete and re-plot, but change the 'XData' and 'YData' property of the old position object.
Note 2
If you aren't already doing so, put the plotting function (the one that updates everything in the plot, not just the position of the load) in a separate function, not into the callback of the slider, and have instead the slider callback call the plot function. This way, you can call the same plotting function from several buttons and sliders, which makes the code a lot easier to maintain.
EDIT
I have updated the commands. Note that there is no special 'tagging' function. 'Tag' is a property of every graphics object, like 'Units', or 'Color'. It simply helps you to label the graphics objects so that you don't need to remember the handles.
Unrelated to the actual question, but related to the project:
http://www.mathworks.com/matlabcentral/fileexchange/2170
This book is still available used on Amazon, it might save you a lot of the coding of the Mechanics of Materials stuff. I wrote this about 12 years ago as an undergrad, but I think the MATLAB code should still be functional.
I want to switch back and forth between two images, like blinking: 1 second for the first image and one second for second image.
I'm not totally sure of what you want to do (specifically what type of images you are trying to display), but here's some sample code that may do what you want:
image1 = imread('cameraman.tif'); % Load a test image
image2 = imread('circles.png'); % Load another test image
hAxes = gca; % Get a handle to the current axes
for iLoop = 1:5, % Loop five times
imshow(image1,'Parent',hAxes);
pause(1);
imshow(image2,'Parent',hAxes);
pause(1);
end
I used the general function IMSHOW, but this sometimes changes other properties of the figure/axes and that may not be to your liking (since you mention adding this to an existing GUI). You may want to use the IMAGE function instead. Also, instead of the for loop you could use a while loop that stops switching images when a condition is met (such as a button press).
How are your images stored in Matlab? As a matlab movie or a 3 or 4 dimensional matrix depending on if the images are color or grayscale. Also, if you have the image processing toolbox, implay and immovie. Another option assuming that your images are in a mxnx3xk (rgb color) or a mxnxk (gray scale) matrix. Then the following should work. Assuming the following
Img - matrix storing image data either with dimensions mxnx3xk
or mxnxk
handles.imageAxes -
handle for the axis you want to
display the image (set the tag of the
axis to imageAxes in GUIDE)
Now you can loop through Img
for i=1:k
% display the i^th image use `Img(:,:,i)` for a gray scale stack
image(Img(:,:,:,i),'parent',handles.imageAxes);
pause(1) % pause one second
end
that's it.