I want develop an matlab's application that can show the bounding box to the object in the image.
I have detected the object, and cropped it.
And now, for the boundng box, i just have to add 10 in all my pixel.
For exmpl:
x=x+10;
y=y+10;
w=w+10;
h=h+10;
I use imcrop function.
But the problem is that i dont understand how to get the pixel's coordinates from imcrop.
[I_crop, I_rect]=imcrop(ImSeq(:,:,1),[])
I_rect=floor(I_rect);
final_rect=I_rect;
for t=1:NumImages
cur_r=final_rect(2);
cur_c=final_rect(1);
for r= cur_r -10:cur_r+10
for c=cur_c-10:cur_c+10
temp= abs(I_crop-ImSeq(r:r+I_rect(4),c:c+I_rect(3),t));
what is final_rect(2), final_rect(1), I_rect(4) and I_rect(3)?
How i can get the coordinates of x,y,w,h of the cropped image??
Thanks
In [I2 rect] = imcrop(I), rect is the cropping rectangle, a four-element position vector. Within the original image, the cropped area is defined by:
rect(2) the current row
rect(1) the current column
rect(3) is the width
rect(4) the height.
Related
I create a polygon on image_area in matlab.
I used impoly.
But after creation polygon.
I need to block possibility to move and drag impoly (ROI is already created).
I don't know how I should do it ?
I would appreciate for any help please.
You can set the makeConstrainToRectFcn such that it is a rectangle encompassing your ROI, then whenever you try to move the latter it won't work. You can also, after creating the ROI, set the setVerticesDraggable method to false in order to prevent vertices from being dragged.
Sample code (adapted from example by the Mathworks):
clc
clear
figure
imshow('gantrycrane.png');
h = impoly(gca, [188,30; 189,142; 93,141; 13,41; 14,29]);
%// Get currentposition
Pos = getPosition(h);
%// Prevent draggable vertices
setVerticesDraggable(h,0);
%// Set up rectangle to prvent movement of ROI
fcn = makeConstrainToRectFcn('impoly', [min(Pos(:,1)) max(Pos(:,1))], [min(Pos(:,2)) max(Pos(:,2))]);
%// Apply function
h.setPositionConstraintFcn(fcn);
which results in this kind of situation (with red rectangle for illustration):
I have a scene filled with ~hundred oblong asteroid shaped objects. I want to place a text label under each one so that the label is visible from any camera angle. I billboard the text so that it always faces the camera.
At first, everything looks great by placing text below the 3d object using .translateY. However, as you start to moving around the scene, labels no longer are 'below' the object depending on your camera position. This especially true when you orient using trackballControls.
How can I place text 'below' the object no matter the orientation. Perhaps if I create a 2d bounding box around each object in relation to the camera on each frame - I could then place the text label right below that 2d box.
I'm also concerned that calculating 2d bounding boxes on a hundred 3d objects every frame could get expensive. Thoughts?
screenshots:
At first, text labels appear correctly translated -y below the object
but as you rotate the camera, labels get sideways
flipping the camera all the way around shows the labels upside down
My goal is to have the labels below the objects no matter the camera orientation.
Did you tried to add the Text Labels to the Object?
object.add(Label) instead of scene.add(Label)
I have a demo site here that might help give you source to look at:
https://dl.dropboxusercontent.com/u/31495717/cubemaker/index.html
This site places textual DOM elements at a screen coordinate-based constant distance from a 3D object, styled with CSS, within the render loop, when the mouse pointer is moved over the 3D object.
From the source:
var id_label = document.createElement('div');
id_label.id = INTERSECTED.name;
id_label.style.position = 'absolute';
id_label.style.top = '-10000px';
id_label.style.left = '-10000px';
id_label.innerHTML = '<span class="particle_label">' + INTERSECTED.name + '<br><span class="particle_sublabel">' + INTERSECTED.subname + '</span></span>';
container.appendChild(id_label);
var id_label_rect = id_label.getBoundingClientRect();
id_label.style.top = (screen_object_center.y - 0.85 * (id_label_rect.height / 2)) + 'px';
if (mouse.x < 0)
id_label.style.left = (screen_object_center.x - horizontal_fudge * (screen_object_edge.x - screen_object_center.x)) + 'px';
else {
id_label.style.left = (screen_object_center.x + horizontal_fudge * (screen_object_edge.x - screen_object_center.x) - id_label_rect.width) + 'px';
id_label.style.textAlign = 'right';
}
The DOM element is drawn offscreen and then repositioned based on attributes of its bounding box and the world coordinates of the 3D element it is associated with. When the mouse pointer is moved outside the 3D element bounds, the text label is removed from the DOM.
Since you are always showing your labels, you might modify this to draw the element once in an initialization step, and simply change the top and left style attributes within the render loop.
I am writing a function that generates a movie mimicking a particle in a fluid. The movie is coloured and I would like to generate a grayscaled movie for the start. Right now I am using avifile instead of videowriter. Any help on changing this code to get grayscale movie? Thanks in advance.
close all;
clear variables;
colormap('gray');
vidObj=avifile('movie.avi');
for i=1:N
[nx,ny]=coordinates(Lx,Ly,Nx,Ny,[x(i),-y(i)]);
[xf,yf]=ndgrid(nx,ny);
zf=zeros(size(xf))+z(i);
% generate a frame here
[E,H]=nfmie(an,bn,xf,yf,zf,rad,ns,nm,lambda,tf_flag,cc_flag);
Ecc=sqrt(real(E(:,:,1)).^2+real(E(:,:,2)).^2+real(E(:,:,3)).^2+imag(E(:,:,1)).^2+imag(E(:,:,2)).^2+imag(E(:,:,3)).^2);
clf
imagesc(nx/rad,ny/rad,Ecc);
writetif(Ecc,i);
if i==1
cl=caxis;
else
caxis(cl)
end
axis image;
axis off;
frame=getframe(gca);
cdata_size = size(frame.cdata);
data = uint8(zeros(ceil(cdata_size(1)/4)*4,ceil(cdata_size(2)/4)*4,3));
data(1:cdata_size(1),1:cdata_size(2),1:cdata_size(3)) = [frame.cdata];
frame.cdata = data;
vidObj = addframe(vidObj,frame);
end
vidObj = close(vidObj);
For your frame data, use rgb2gray to convert a colour frame into its grayscale counterpart. As such, change this line:
data(1:cdata_size(1),1:cdata_size(2),1:cdata_size(3)) = [frame.cdata];
To these two lines:
frameGray = rgb2gray(frame.cdata);
data(1:cdata_size(1),1:cdata_size(2),1:cdata_size(3)) = ...
cat(3,frameGray,frameGray,frameGray);
The first line of the new code will convert your colour frame into a single channel grayscale image. In colour, grayscale images have all of the same values for all of the channels, which is why for the second line, cat(3,frameGray,frameGray,frameGray); is being called. This stacks three copies of the grayscale image on top of each other as a 3D matrix and you can then write this frame to your file.
You need to do this stacking because when writing a frame to file using VideoWriter, the frame must be colour (a.k.a. a 3D matrix). As such, the only workaround you have if you want to write a grayscale frame to the file is to replicate the grayscale image into each of the red, green and blue channels to create its colour equivalent.
BTW, cdata_size(3) will always be 3, as getframe's cdata structure always returns a 3D matrix.
Good luck!
So lets say I have black & white image that is read with imread() command and saved into matrix A.
I want to output/graph this matrix A image in a cylinder shape. I know how to draw a cylinder in MATLAB, but I do not have a clue what I should do if I want to put image on a cylinder or draw image in cylinder shape. Any help will be appreciated. Thank you.
I found this site from googling.
http://www.flashandmath.com/advanced/rolls/cylin.html
This is exactly what I want to do, but I need to do this in MATLAB.
The technique is called texture mapping. This is a code example from surface function (R2011b):
load clown
surface(peaks,flipud(X),...
'FaceColor','texturemap',...
'EdgeColor','none',...
'CDataMapping','direct')
colormap(map)
view(-35,45)
This example loads RGB image from "peppers.png" and maps it onto cylinder:
imgRGB = imread('peppers.png');
[imgInd,map] = rgb2ind(imgRGB,256);
[imgIndRows,imgIndCols] = size(imgInd);
[X,Y,Z] = cylinder(imgIndRows,imgIndCols);
surface(X,Y,Z,flipud(imgInd),...
'FaceColor','texturemap',...
'EdgeColor','none',...
'CDataMapping','direct')
colormap(map)
view(-35,45)
Things are even simpler with the warp function (comes with Image Processing toolbox) as natan suggested:
imgRGB = imread('peppers.png');
[imgRows,imgCols,imgPlanes] = size(imgRGB);
[X,Y,Z] = cylinder(imgRows,imgCols);
warp(X,Y,Z,imgRGB);
I'm looking for how can I display an image in my GUI in a specific region of my interface.
In GUIDE, you can draw axes into the GUI. Then, in a callback function, you can plot an image into the axes.
Personally, I would rather not have the image inside the GUI, because it makes it harder to resize everything properly, and if you want to have a closer look at the image, or capture it to paste into another application, having the figure as part of the GUI can be inconvenient. Thus, I prefer to have the image open in a separate figure window.
Try the following code:
function movingimage
%# Plotting a figure
fig1=figure('Name','Plotting an image',...
'Unit','normalized', 'Position',[.1 .1 .8 .8]);
uicontrol(fig1,'Style','text','Unit','Normalized',...
'Position',[.9 .85 .1 .07],'String','Press the button below to move the image location.');
uicontrol(fig1,'Style','pushbutton','Unit','Normalized',...
'Position',[.9 .8 .05 .05],'String','Move','Callback',{#action_Callback});
%# Say, you wish to plot an image of relative dimension (.3 x .3) to the figure.
xdim=.3; ydim=.3;
%# Image's movable range in x is (1 - xdim)
dx=1-xdim;
%# Image's Movable range in y is (1 - ydim)
dy=1-ydim;
%# considering the size of the image...
pos = [.5*dx .5*dy xdim ydim]; %# Initial location of the image is at the center of the figure.
ax1 = axes('position',pos);
img = load('mandrill');
image(img.X)
colormap(img.map);axis off;axis equal;
function action_Callback(hObj,eventdata)
pos=[rand(1)*dx rand(1)*dy xdim ydim];
set(ax1,'position',pos);
end
end
The most direct and easy way I find to do this is to use the Axis component as shown in this tutorial:
http://www.aboutcodes.com/2012/06/how-to-display-image-in-gui-using.html