Let's say my image is img=zeros(100,100,3), my outputs are several ellipse which i get using a created function [ret]=draw_ellipse(x,y,a,b,angle,color,img), I can display one ellipse using imshow(ret).For the moment, I'm trying to show serval ellipse in the image. But i don't know how to code it. will ‘for loop’ work or I need to hold them?
If this is related to what you were doing in your previous question, then what you need to do is to pass the result of one iteration as input to the next.
So assuming that the function [ret]=draw_ellipse(x,y,a,b,angle,color,img) you mentioned takes as input an image img and returns the same image with an ellipse drawn on it, you could do this:
%# ellipses parameters
%#x = {..}; y = {..};
%#a = {..}; b = {..};
%#angle = {..}; color = {..};
img = zeros(200,100,'uint8'); %# image to start with
for i=1:10
img = draw_ellipse(x{i},y{i}, a{i},b{i}, angle{i}, color{i}, img);
end
imshow(img)
I'm a bit unsure of what you want. You want to show several ellipse in one image, like plotting several graphs with hold on?
There is no equivalent command for images, but a simple solution is to add the ellipses into one image and show that one:
several_ellipse = ellipse1 + ellipse2 + ellipse3;
imshow(several_ellipse)
Presumably you want to pass ret as the final input to the next call to draw_ellipse.
Related
I try to determine the coordinates of a puzzle piece on the original image using the normxcorr2 function. Then I draw a rectangle on the correspondence of the two elements. Unfortunately, I notice that the coordinates that this match has given me are not good. Could someone have an idea how to improve the use of this feature and get some better results.
The puzzle piece has the name "cpiece" and the original picture has the name "bild"
clear all;
close all;
clc
cpiece = im2gray(imread('cpiece1.jpg'));
bild = im2gray(imread('original.jpg'));
figure(1)
montage({bild,cpiece})
c = normxcorr2(cpiece,bild);
figure(2)
surf(c)
shading flat
[ypeak,xpeak] = find(c==max(c(:)));
yoffSet = ypeak-size(cpiece,1);
xoffSet = xpeak-size(cpiece,2);
figure(3)
imshow(bild)
drawrectangle(gca,'Position',[xoffSet,yoffSet,size(cpiece,2),size(cpiece,1)],'FaceAlpha',0);
It seems, the problem returns back to the quality of your template image, And Check if the scales between original image and the template are exactly the same
I'm trying to combine the two images based on the information from the mask. I'm using the color information from the background image if the mask is 0 and color information from foreground image if the mask is 1. Because the mask and both
Images are of the same size, I would like to use logical indexing of matrices to achieve this.
My attempt:
mask = imread('mask.png');
foreground = imread('fg.jpg');
background = imread('bg.jpg');
[r,c,~]=size(mask);
A = zeros(size(mask));
for i=1:r
for j=1:c
if mask(i,j) == 0
A(i,j,:) = background(i,j,:);
end
if mask(i,j) > 0
A(i,j,:) = foreground(i,j,:);
end
end
end
imshow(A);
The result looks like a flickering blue image, but I don't want that. Please help.
You can do this a bit more concisely:
f = double(foreground).*double(mask);
b = double(background).*double(~mask);
blend = f+b;
imshow(blend, []);
Using logical indexing you could also do
foreground(logical(mask)) = 0;
background(logical(~mask)) = 0;
blend = foreground+background;
The ISNOT operator '~' inverts your matrix in the second line, so you cut out the area you would like for background.
NOTE: This works for black and white (one channel). For coloured images see rayryeng's solution.
There are two problems with your code. The first problem is that you are trying to assign colour pixels to the output image A, yet this image is only two-dimensional. You want an image with three channels, not two. In addition, the output image type you are specifying is wrong. By default, the output image A is of type double, yet you are copying values into it that aren't double... most likely unsigned 8-bit integer.
As such, cast the image to the same type as the input images. Assuming both input images are the same type, initialize your A so that:
A = zeros(size(foreground), class(foreground));
This correctly makes a colour image with the same type as any of the inputs, assuming that they're both the same type.
Now, your for loop is fine, but it's better if you do this in one shot with logical indexing. If you want to use logical indexing, create a new image that's initially blank like what you've done, but then make sure your mask has three channels to match the number of channels the other images have. After, you simply need to index into each image and set the right locations accordingly:
mask = imread('mask.png');
foreground = imread('fg.jpg');
background = imread('bg.jpg');
[r,c,d]=size(mask); %// Change
%// If your mask isn't three channels, make it so
%// Change
if d ~= 3
mask = cat(3, mask, mask, mask);
end
A = zeros(size(foreground), class(foreground)); %// Change
A(mask) = foreground(mask); %// Assign pixels to foreground
A(~mask) = background(~mask); %// Assign pixels to background
imshow(A);
How to make '.gif' image from a set of '.jpg' images (say: I1.jpg, I2.jpg,..., I10.jpg) in matlab?
Ok here is a simple example. I got an image with a unicorn on it and remove 2 part to create 3 different images, just for the sake of creating an animated gif. Here is what it looks like:
clear
clc
%// Image source: http:\\giantbomb.com
A = rgb2gray(imread('Unicorn1.jpg'));
B = rgb2gray(imread('Unicorn2.jpg'));
C = rgb2gray(imread('Unicorn3.jpg'));
ImageCell = {A;B;C};
figure;
subplot(131)
imshow(A)
subplot(132)
imshow(B)
subplot(133)
imshow(C)
%// Just to show what the images look like (I removed spots to make sure there was an animation created):
%// Create file name.
FileName = 'UnicornAnimation.gif';
for k = 1:numel(ImageCell)
if k ==1
%// For 1st image, start the 'LoopCount'.
imwrite(ImageCell{k},FileName,'gif','LoopCount',Inf,'DelayTime',1);
else
imwrite(ImageCell{k},FileName,'gif','WriteMode','append','DelayTime',1);
end
end
As you see, its not that different from the example on the Mathworks website. Here my images are in a cell array but yours might be in a regular array or something else.That should work fine; when I open 'UnicornAnimation.gif' it is indeed a nice animation!
Hope that helps!
I am modifying images in matlab and I have a problem.
I need to separate the 3 channels of color and modify them separately.
I use this to obtain the three channels:
a = imread('./images/penguins.png');
colorlist = {'R','G','B'};
subplot(2,2,1);
imshow(a);
for k=1:3
subplot(2,2,k+1);
imshow( a(:,:,k));
title(colorlist{k});
end
a(:,:,k) is one color of the three. The problem is when I add the three vectors in one, to obtain the color image. I do this:
A=a(:,:,1)+a(:,:,2)+a(:,:,3)
figure; imshow(A);
But it dont works, it only show me a very highlight image, no a color image.
Anyone knows how can I recover the color image? Thanks for yout help^^
You are adding the values of the three layers instead of concatenating them in a 3D array.
Try this:
A= cat(3, a(:,:,1), a(:,:,2), a(:,:,3));
I should also note that you can edit the layers simply by indexing, say you want to switch the red and green components:
I1 = imread('http://i.stack.imgur.com/1KyJA.jpg');
I2=I1;
I2(:,:,1)=I1(:,:,2);
I2(:,:,2)=I1(:,:,1);
imshowpair(I1,I2, 'montage');
Now if I take your title literally, let's say you do want to add the three layers and display the result with a colormap, you can do:
A=a(:,:,1)+a(:,:,2)+a(:,:,3)
imagesc(A); axis image;
colorbar;
Results:
I'm trying to use the answers I found in these questions:
How to save a plot into a PDF file without a large margin around
Get rid of the white space around matlab figure's pdf output
External source
to print a matlab plot to pdf without having the white margins included.
However using this code:
function saveTightFigure( h, outfilename, orientation )
% SAVETIGHTFIGURE(H,OUTFILENAME) Saves figure H in file OUTFILENAME without
% the white space around it.
%
% by ``a grad student"
% http://tipstrickshowtos.blogspot.com/2010/08/how-to-get-rid-of-white-margin-in.html
% get the current axes
ax = get(h, 'CurrentAxes');
% make it tight
ti = get(ax,'TightInset');
set(ax,'Position',[ti(1) ti(2) 1-ti(3)-ti(1) 1-ti(4)-ti(2)]);
% adjust the papersize
set(ax,'units','centimeters');
pos = get(ax,'Position');
ti = get(ax,'TightInset');
set(h, 'PaperUnits','centimeters');
set(h, 'PaperSize', [pos(3)+ti(1)+ti(3) pos(4)+ti(2)+ti(4)]);
set(h, 'PaperPositionMode', 'manual');
set(h, 'PaperPosition',[0 0 pos(3)+ti(1)+ti(3) pos(4)+ti(2)+ti(4)]);
% save it
%saveas(h,outfilename);
if( orientation == 1)
orient portrait
else
orient landscape
end
print( '-dpdf', outfilename );
end
Results in this output:
As you can see the 'PaperSize' seems to be set not properly. Any idea of possible fixes?
NOTE
If I change the orientation between landscape and portrait the result is the same, simply the image is chopped in a different way.
However if I save the image with the saveas(h,outfilename); instruction the correct output is produced.
Why is this? And what is the difference between the two saving instructions?
Alltogether the answers you mentioned offer a lot of approaches, but most of them didn't worked for me neither. Most of them screw up your papersize when you want to get the tight inset, the only which worked for me was:
set(axes_handle,'LooseInset',get(axes_handle,'TightInset'));
I finally wrote a function, where I specify the exact height and width of the output figure on paper, and the margin I want (or just set it to zero). Be aware that you also need to pass the axis handle. Maybe this functions works for you also.
function saveFigure( fig_handle, axes_handle, name , height , width , margin)
set(axes_handle,'LooseInset',get(axes_handle,'TightInset'));
set(fig_handle, 'Units','centimeters','PaperUnits','centimeters')
% the last two parameters of 'Position' define the figure size
set(fig_handle,'Position',[-margin -margin width height],...
'PaperPosition',[0 0 width+margin height+margin],...
'PaperSize',[width+margin height+margin],...
'PaperPositionMode','auto',...
'InvertHardcopy', 'on',...
'Renderer','painters'... %recommended if there are no alphamaps
);
saveas(fig_handle,name,'pdf')
end
Edit: if you use painters as renderer saveas and print should produce similar results. For jpegs print is preferable as you can specify the resolution.