I have a question about the values returned by getPosition. Below is my code. It lets the user set 10 points on a given image:
figure ,imshow(im);
colorArray=['y','m','c','r','g','b','w','k','y','m','c'];
pointArray = cell(1,10);
% Construct boundary constraint function
fcn = makeConstrainToRectFcn('impoint',get(gca,'XLim'),get(gca,'YLim'));
for i = 1:10
p = impoint(gca);
% Enforce boundary constraint function using setPositionConstraintFcn
setPositionConstraintFcn(p,fcn);
setColor(p,colorArray(1,i));
pointArray{i}=p;
getPosition(p)
end
When I start to set points on the image I get results like [675.000 538.000], which means that the x part of the coordinate is 675 and the y part is 538, right? This is what the MATLAB documentation says, but since the image is 576*120 (as displayed in the window) this is not logical.
It seemed to me like, somehow, getPosition returns the y coordinate first. I need some clarification on this.
Thanks for help
I just tried running your code in MATLAB 7.8.0 (R2009a) and had no problems with image sizes of either 576-by-120 or 120-by-576 (I was unsure which orientation you were using). If I left click inside the image, it places a new movable point. It did not allow me to place any points outside the image.
One small bug I found was that if you left-click in the image, then drag the mouse pointer outside the image while still holding the left button down, it will place the movable point outside the image and won't display it, displaying a set of coordinates that are not clipped to the axes rectangle.
I'm not sure of what could be your problem. Perhaps it's a bug with whatever MATLAB version you are using. I would suggest either restarting MATLAB, or clearing all variables from the workspace (except for the image data im).
Might be worth checking to see which renderer you are using (Painter or OpenGL), a colleague showed me some wierd behaviour with point picking when using the OpenGL renderer which went away when using the Painter renderer.
Your code uses the Image Processing Toolbox, which I don't have, so this is speculation. The coordinate system is probably set to the figure window (or maybe even the screen), not the image.
To test this, try clicking points outside the image to see if you can find the origin.
Related
I currently use Matlab's imshow to output an image at every iteration of a diffusion filter process, i.e. multiple times per second.
Sometimes during filtering I want a closer look at specific image parts.
However, when using the ('Parent', handle) name-value pair for imshow the magnification and position gets reset.
Is there a way to update the underlying image but having the magnification and position intact?
You can update the cdata in the current axis to your new data matrix which will keep all other settings the same. If this is in a loop, you probably need to call drawnow. E.g:
x=randn(100);
figure;imagesc(x);
Now zoom / pan / do whatever manipulations you want.
f=gca;
x=randn(100);
f.Children.CData = x;
This method of updating of child data is recommended by Matlab as more efficient than destroying the axis child Image and recreating each frame (can't remember the source, it was in one of the help files).
Edit: Just remembered that this syntax won't work on older versions of matlab (pre 2015 or so). In that case, use get/set syntax:
set(get(gca,'Children'),'CData',x);
I have used matlab's preview window in the following syntax:
figure('Name', 'My Custom Preview Window');uicontrol('String', 'Close', 'Callback', 'close(gcf)');
I am able to successfully get the video stream. Now I want to have a small circle as a region of interest to return the average pixel value within this circle. I want this to be stored and named after a click of a button and recalled later for the further processing.
Could anyone guide me where I can start with?
Please note I dont want user to define ROI instead its always fixed as a small circle at the centre of field view. Whatever the colours comes within the circle I want mean values to be calculated and stored as a reference.
Ps: I am not sure I am correct in calling ROI its simple circle in the field view
You might want to try using a Matlab gui instead of a simple figure. Then you could try something like this.
I am currently using the fill command in MATLAB to create a graph of boxes that were created using the 'fill' command (the actual code is based off this StackOverflow Question.
My issue is that the boxes that I create do not have "corners." I am attaching a PNG that illustrates the issue. Note that you have to look a little carefully since the image was heavily rendered, though in this example my arrows also look weird since they don't have edges either)
I am wondering if anyone has an idea of what might be going wrong? The boxes appear this way immediately after I use the fill command, which has the following structure:
fill(X,Y,MyFaceColor,'FaceAlpha',0.5,'EdgeColor', MyEdgeColor,'LineStyle','','LineWidth',box_line_width,'EdgeAlpha',1)
The function fill appears to leave space for corner markers if they are not explicitly defined. Hence, calling fill with the marker property will solve your problem. However, since markers and linewidths seem to work on different scales, you will have to play around with the marker size to get smooth edges.
Example:
fill(X,Y,'r','FaceAlpha',0.5,'EdgeColor', 'k',...
'LineWidth', 5,'EdgeAlpha',1 , 'marker', '.', 'markersize', 15)
Does any one here have an idea about how to change the position of output in the GUI matlab to be to the right side of the box and not in the center ?
i think I have to change some properties of the result text box
Check this post out: Positioning of figures
The figure Position property controls the size and location of the figure window on the screen. Monitor screen size is a property of the root Handle Graphics object. At startup, the MATLAB software determines the size of your computer screen and defines a default value for Position. This default creates figures about one-quarter of the screen's minimum extent and places them centered left to right, in the top half of the screen.
The Position Vector
MATLAB defines the figure Position property as a vector. So you may use a figure and text into it, e.g.
figure(gcf)
text(offsetX1, offsetX1, ['result 1: ' num2str(result1)])
text(offsetX2, offsetX2, ['result 2: ' num2str(result2)])
Displaying analytical results in a MATLAB GUI
This post talks about adding a static textbox with your results and positioning it.
Move GUI figure to specified location on screen:
Syntax:
movegui(h,'position')
movegui(position)
movegui(h)
movegui
The answer is pretty much trying to cover up the vauge nature of the question
I would like to add text annotation to a figure from a GUI made with GUIDE. First I plot some data, than when the user clicks on a checkbox I call the text function in the event handler like this:
text(obj.XData(q), obj.YData(q)+10, int2str(q), 'Units', 'pixels');
obj is the line object itself, q is a counter for each point in the plot. It runs without errors, but nothing happens. I suppose I should 'refresh' the axis somehow, but refresh command doesn't help and I haven't found anything in the documentation.
Edit: I have found out that my code was wrong: pixel units correspond to a coordinate system where the origin is the lower-left corner of my axis control, what is not the same as my data coordinate system. I fixed this problem with ds2nfu, and when I paint before plotting everything is fine. But after plotting I see nothing. Is it possible that there is some kind of z-order problem with annotations?
As I mentioned in the comments, you should use the normalized units to place things in the same coordinate system as the data.
Now for the other problem. I'm not sure if this is a z-order issue, but if it is, you can bring the text to the front using UISTACK:
hText = text(x,y,'str');
uistack(hText, 'top')