Binarizing 3-channel images - matlab

circle_folder = 'C:\Users\MyPC\Documents\CR\start\circle';
name_circle = dir(fullfile(circle_folder, '*.png'));
total_circle = numel(name_circle);
rez_circle = [25 25];
m_circle = zeros(25*25, 5);
for n_circle = 1:total_circle
full_circle = fullfile(circle_folder, name_circle(n_circle).name);
images_circle = imread(full_circle);
images_circle = imresize(images_circle, rez_circle);
store_circle = imbinarize(images_circle);
store_circle = store_circle(:);
m_circle(:, n_circle) = store_circle;
figure(n_circle);
imshow(m_circle);
end
I'm trying to pull images from the folder in question, resize them to 25 by 25 pixels, then turn them into a binary matrix. The code works until the point i attempt to fit the images into said matrix. If I make the matrix bigger, so it becomes 1875-by-1, it works, however, I do need the matrix to be of this size.

What happened is that you loaded an m-by-n-by-3 image, i.e. a 3 channel image. You used imresize() to resize each channel independently, ending up with a 25-by-25-by-3 image. imbinarize() finally works on each channel separately as well.
Instead, before resizing, call rgb2gray(images_circle) to change your 3 channel image to a 1 channel image. Then you can call imresize() and imbinarize(), resulting in your desired 25-by-25 binary image.

Related

Matlab - Removing image background using normalization

I have an image like this:
my goal is to get the output under background normalization at this link.
Following the above link, I did the following:
(1). I first dilate the image to get the background
(2). then try to remove it via normalization
I got the background:
However, when I try to do the normalized division, I get this :
(black borders added to make clear of the boundary of the image)
this is my code:
image = imread('image.png');
image = rgb2gray(image);
se = offsetstrel('ball',9,9);
dilatedI = imdilate(image,se);
output = imdivide(image,dilatedI);
imshow(output,[]);
using
imshow(output)
just gives a black image.
I thought it might be a type conversion issue, but based on the resources mentioned earlier, I am uncertain if it is the case...
Any advice would be appreciated
Just make sure you dont do integer division! your images are integer type, so 4/5 returns 0 and 5/4 returns 1, not a floating point number. Just convert to float before dividing:
image = imread('https://i.stack.imgur.com/bIVRT.png');
%image = rgb2gray(image); The image is not a RGB online
se = offsetstrel('ball',21,21);
dilatedI = imdilate(image,se);
output = imdivide(double(image),double(dilatedI));
figure
subplot(121)
imshow(image);
subplot(122)
imshow(output);

Smooth and fit edge of binary images

i am working on a research about the swimming of fishes using analysis of videos, then i need to be carefully with the images (obtained from video frames) with emphasis in the tail.
The images are in High-Resolution and the software that i customize works with binary images, because is easy to use maths operations on this.
For obten this binary images i use 2 methods:
1)Convert the image to gray, invert the colors,later to bw and finally to binary with a treshold that give me images like this, with almost nothing of noise. The images sometimes loss a bit of area and doesn't is very exactly with the tail(now i need more acurracy for determinate the amplitude of tail moves)
image 1
2)i use this code, for cut the border that increase the threshold, this give me a good image of the edge, but i dont know like joint these point and smooth the image, or fitting binary images, the app fitting of matlab 2012Rb doesn't give me a good graph and i don't have access to the toolboxs of matlab.
s4 = imread('arecorte.bmp');
A=[90 90 1110 550]
s5=imcrop(s4,A)
E = edge(s5,'canny',0.59);
image2
My question is that
how i can fit the binary image or joint the points and smooth without disturb the tail?
Or how i can use the edge of the image 2 to increase the acurracy of the image 1?
i will upload a image in the comments that give me the idea of the method 2), because i can't post more links, please remember that i am working with iterations and i can't work frame by frame.
Note: If i ask this is because i am in a dead point and i don't have the resources to pay to someone for do this, until this moment i was able to write the code but in this final problem i can't alone.
I think you should use connected component labling and discard the small labels and than extract the labels boundary to get the pixels of each part
the code:
clear all
% Read image
I = imread('fish.jpg');
% You don't need to do it you haef allready a bw image
Ibw = rgb2gray(I);
Ibw(Ibw < 100) = 0;
% Find size of image
[row,col] = size(Ibw);
% Find connceted components
CC = bwconncomp(Ibw,8);
% Find area of the compoennts
stats = regionprops(CC,'Area','PixelIdxList');
areas = [stats.Area];
% Sort the areas
[val,index] = sort(areas,'descend');
% Take the two largest comonents ids and create filterd image
IbwFilterd = zeros(row,col);
IbwFilterd(stats(index(1,1)).PixelIdxList) = 1;
IbwFilterd(stats(index(1,2)).PixelIdxList) = 1;
imshow(IbwFilterd);
% Find the pixels of the border of the main component and tail
boundries = bwboundaries(IbwFilterd);
yCorrdainteOfMainFishBody = boundries{1}(:,1);
xCorrdainteOfMainFishBody = boundries{1}(:,2);
linearCorrdMainFishBody = sub2ind([row,col],yCorrdainteOfMainFishBody,xCorrdainteOfMainFishBody);
yCorrdainteOfTailFishBody = boundries{2}(:,1);
xCorrdainteOfTailFishBody = boundries{2}(:,2);
linearCorrdTailFishBody = sub2ind([row,col],yCorrdainteOfTailFishBody,xCorrdainteOfTailFishBody);
% For visoulaztion put color for the boundries
IFinal = zeros(row,col,3);
IFinalChannel = zeros(row,col);
IFinal(:,:,1) = IFinalChannel;
IFinalChannel(linearCorrdMainFishBody) = 255;
IFinal(:,:,2) = IFinalChannel;
IFinalChannel = zeros(row,col);
IFinalChannel(linearCorrdTailFishBody) = 125;
IFinal(:,:,3) = IFinalChannel;
imshow(IFinal);
The final image:

How do I convert the whole image to grayscale except for a sub image which should be in color?

I have an image and a subimage which is cropped out of the original image.
Here's the code I have written so far:
val1 = imread(img);
val2 = imread(img_w);
gray1 = rgb2gray(val1);%grayscaling both images
gray2 = rgb2gray(val2);
matchingval = normxcorr2(gray1,gray2);%normalized cross correlation
[max_c,imax]=max(abs(matchingval(:)));
After this I am stuck. I have no idea how to change the whole image grayscale except for the sub image which should be in color.
How do I do this?
Thank you.
If you know what the coordinates are for your image, you can always just use the rgb2gray on just the section of interest.
For instance, I tried this on an image just now:
im(500:1045,500:1200,1)=rgb2gray(im(500:1045,500:1200,1:3));
im(500:1045,500:1200,2)=rgb2gray(im(500:1045,500:1200,1:3));
im(500:1045,500:1200,3)=rgb2gray(im(500:1045,500:1200,1:3));
Where I took the rows (500 to 1045), columns (500 to 1200), and the rgb depth (1 to 3) of the image and applied the rgb2gray function to just that. I did it three times as the output of rgb2gray is a 2d matrix and a color image is a 3d matrix, so I needed to change it layer by layer.
This worked for me, making only part of the image gray but leaving the rest in color.
The issue you might have though is this, a color image is 3 dimensions while a gray scale need only be 2 dimensions. Combining them means that the gray scale must be in a 3d matrix.
Depending on what you want to do, this technique may or may not help.
Judging from your code, you are reading the image and the subimage in MATLAB. What you need to know are the coordinates of where you extracted the subimage. Once you do that, simply take your original colour image, convert that to grayscale, then duplicate this image in the third dimension three times. You need to do this so that you can place colour pixels in this image.
For RGB images, grayscale images have the RGB components to all be the same. Duplicating this image in the third dimension three times creates the RGB version of the grayscale image. Once you do that, simply use the row and column coordinates of where you extracted the subimage and place that into the equivalent RGB grayscale image.
As such, given your colour image that is stored in img and your subimage stored in imgsub, and specifying the rows and columns of where you extracted the subimage in row1,col1 and row2,col2 - with row1,col1 being the top left corner of the subimage and row2,col2 is the bottom right corner, do this:
img_gray = rgb2gray(img);
img_gray = cat(3, img_gray, img_gray, img_gray);
img_gray(row1:row2, col1:col2,:) = imgsub;
To demonstrate this, let's try this with an image in MATLAB. We'll use the onion.png image that's part of the image processing toolbox in MATLAB. Therefore:
img = imread('onion.png');
Let's also define our row1,col1,row2,col2:
row1 = 50;
row2 = 90;
col1 = 80;
col2 = 150;
Let's get the subimage:
imgsub = img(row1:row2,col1:col2,:);
Running the above code, this is the image we get:
I took the same example as rayryeng's answer and tried to solve by HSV conversion.
The basic idea is to set the second layer i.e saturation layer to 0 (so that they are grayscale). then rewrite the layer with the original saturation layer only for the sub image area, so that, they alone have the saturation values.
Code:
img = imread('onion.png');
img = rgb2hsv(img);
sPlane = zeros(size(img(:,:,1)));
sPlane(50:90,80:150) = img(50:90,80:150,2);
img(:,:,2) = sPlane;
img = hsv2rgb(img);
imshow(img);
Output: (Same as rayryeng's output)
Related Answer with more details here

Changing image aspect ratio of interpolated RGB image. Square to rectangular

I have some code which takes a fish eye images and converts it to a rectangular image in each RGB channels. I am having trouble with the fact the the output image is square instead of rectangular. (this means that the image is distorted, compressed horizontally.) I have tried changing the output matrix to a more suitable format, without success. Besides this i have also discovered that for the code to work the input image must be square like 500x500. Any idea how to solve this issue? This is the code:
The code is inspired by Prakash Manandhar "Polar To/From Rectangular Transform of Images" file exchange on mathworks.
EDIT. Code now works.
function imP = FISHCOLOR2(imR)
rMin=0.1;
rMax=1;
[Mr, Nr, Dr] = size(imR); % size of rectangular image
xRc = (Mr+1)/2; % co-ordinates of the center of the image
yRc = (Nr+1)/2;
sx = (Mr-1)/2; % scale factors
sy = (Nr-1)/2;
reduced_dim = min(size(imR,1),size(imR,2));
imR = imresize(imR,[reduced_dim reduced_dim]);
M=size(imR,1);N=size(imR,2);
dr = (rMax - rMin)/(M-1);
dth = 2*pi/N;
r=rMin:dr:rMin+(M-1)*dr;
th=(0:dth:(N-1)*dth)';
[r,th]=meshgrid(r,th);
x=r.*cos(th);
y=r.*sin(th);
xR = x*sx + xRc;
yR = y*sy + yRc;
for k=1:Dr % colors
imP(:,:,k) = interp2(imR(:,:,k), xR, yR); % add k channel
end
imP = imresize(imP,[size(imP,1), size(imP,2)/3]);
imP = imrotate(imP,270);
SOLVED
Input image <- Image link
Output image <- Image link
PART A
To remove the requirement of a square input image, you may resize the input image into a square one with this -
%%// Resize the input image to make it square
reduced_dim = min(size(imR,1),size(imR,2));
imR = imresize(imR,[reduced_dim reduced_dim]);
Few points I would like to raise here though about this image-resizing to make it a square image. This was a quick and dirty approach and distorts the image for a non-square image, which you may not want if the image is not too "squarish". In many of those non-squarish images, you would find blackish borders across the boundaries of the image. If you can remove that using some sort of image processing algorithm or just manual photoshoping, then it would be ideal. After that even if the image is not square, imresize could be considered a safe option.
PART B
Now, after doing the main processing of flattening out the fisheye image,
at the end of your code, it seemed like the image has to be rotated
90 degrees clockwise or counter-clockwise depending on if the fisheye
image have objects inwardly or outwardly respectively.
%%// Rotating image
imP = imrotate(imP,-90); %%// When projected inwardly
imP = imrotate(imP,-90); %%// When projected outwardly
Note that the flattened image must have the height equal to the half of the
size of the input square image, that is the radius of the image.
Thus, the final output image must have number of rows as - size(imP,2)/2
Since you are flattening out a fisheye image, I assumed that the width
of the flattened image must be 2*PI times the height of it. So, I tried this -
imP = imresize(imP,[size(imP,2)/2 pi*size(imP,2)]);
But the results looked too flattened out. So, the next logical experimental
value looked like PI times the height, i.e. -
imP = imresize(imP,[size(imP,2)/2 pi*size(imP,2)/2]);
Results in this case looked good.
I'm not very experienced in the finer points of image processing in MATLAB, but depending on the exact operation of the imP fill mechanism, you may get what you're looking for by doing the following. Change:
M = size(imR, 1);
N = size(imR, 2);
To:
verticalScaleFactor = 0.5;
M = size(imR, 1) * verticalScaleFactor;
N = size(imR, 2);
If my hunch is right, you should be able to tune that scale factor to get the image just right. It may, however, break your code. Let me know if it doesn't work, and edit your post to flesh out exactly what each section of code does. Then we should be able to give it another shot. Good luck!
This is the code which works.
function imP = FISHCOLOR2(imR)
rMin=0.1;
rMax=1;
[Mr, Nr, Dr] = size(imR); % size of rectangular image
xRc = (Mr+1)/2; % co-ordinates of the center of the image
yRc = (Nr+1)/2;
sx = (Mr-1)/2; % scale factors
sy = (Nr-1)/2;
reduced_dim = min(size(imR,1),size(imR,2));
imR = imresize(imR,[reduced_dim reduced_dim]);
M=size(imR,1);N=size(imR,2);
dr = (rMax - rMin)/(M-1);
dth = 2*pi/N;
r=rMin:dr:rMin+(M-1)*dr;
th=(0:dth:(N-1)*dth)';
[r,th]=meshgrid(r,th);
x=r.*cos(th);
y=r.*sin(th);
xR = x*sx + xRc;
yR = y*sy + yRc;
for k=1:Dr % colors
imP(:,:,k) = interp2(imR(:,:,k), xR, yR); % add k channel
end
imP = imresize(imP,[size(imP,1), size(imP,2)/3]);
imP1 = imrotate(imP1,270);

Matlab imresize function rounding up pixels

I'm looking to take in an image of 162x193 pixels and basically scale it down by 0.125 i.e 162/8 = 20.25 and 193/8 = 24.125. Thus I would like a picture of size 20x24 The only problem I'm currently having is that when I use the imresize function it rounds up the images pixel values i.e I get an image of size 21x25 instead of 20x24. Any way of getting 20x24 or is this problem something I'm going to have to live with? Here is some code:
//Read in original Image
imageBig = imread(strcat('train/',files(i).name));
//Resize the image
image = imresize(imageBig,0.125);
disp(size(image));
It appears that with the scale argument being provided, imresize ceils up the dimensions as your results show. So, I guess an obvious choice is to manually provide it the rounded values as dimensions.
Code
%%// Scaling ratio
scale1 = 0.125;
%%// Get scaled up/down version
[M,N,~] = size(imageBig);
image = imresize(imageBig,[round(scale1*M) round(scale1*N)]);