There are some white portions in a black object.
I need to cover up the all the white portions in the object with its neighboring black.
The bwlabel function labels the black part as '2' and white part as '1'.
can i somehow change the labels of the required object and cover the white portion with black.
I have isolated the objects individually using the following code:
a=imread('3.jpg');
figure(),imshow(a),title('Original image');
b=im2bw(a, graythresh(a));
figure(),imshow(b),title('Grayscale image');
[c,num]=bwlabel(b);
figure(),imshow(c),title('labelled image');
for i=1:1:num
figure(),imshow(c==i),title('OBJECT');
end
What can i do further ?
Or is there any other way to achieve the same?
Can you do
Find the indices of the white area
ind_white = find(c==1);
Replace the white area with zeros
b(ind_white) = 0;
or you can change the label of the white object to that of the black
c(ind) = 2;
Related
Hello i need to make background color black and foreground color white. As u can see i did this with transfering image to 2 dimension. I want to make this color changes in 3 dimension, so we are nor allowed to transfer it bw. Is there any way to do this ?
logo=imread('logo.png');
subplot(2,2,1);
imshow(logo);
b=rgb2gray(logo);
subplot(2,2,2);
imshow(b);
c=im2bw(b,0.92)
subplot(2,2,3);
imshow(c);
c = 1-c;
subplot(2,2,4);
imshow(c);
Preface:
To set the pixel to white or black each layer of the pixel needs to be set to an intensity value of 0 (black) or 255 (white).
White Pixel → rgb(255,255,255)
Black Pixel → rgb(0,0,0)
The colon can be used to obtain all the indices in the 3rd dimension (grab all the layers). To grab one RGB-pixel in the top-left corner of the image:
RGB_Pixel = Image(1,1,:);
Method 1:
If you wish to retain the three colour channels you can use matrix indexing to change the white background to black. Matrix indexing can also be used to change anywhere that isn't white to white. This method may, unfortunately, break down if you have a coloured component with a 255 intensity component. This doesn't seem to be the case for your image though. You can use method 2 for a more safe approach.
logo = imread('logo.png');
[Image_Height,Image_Width,Depth]= size(logo);
new_logo = zeros(Image_Height,Image_Width,Depth);
new_logo(logo == 255) = 0;
new_logo(logo ~= 255) = 255;
imshow(new_logo);
Method 2:
Checks each pixel (RGB-triplet) using a set of for-loops that scan through the entire image. If the RGB-intensities of the pixel are rgb(255,255,255) then the pixels are set to 0 (black). If the RGB-intensities of the pixel are anything else the pixels are set to 255 (white). The ~ismember() function is used to check if the RGB-pixel has an intensity that is not 255 (not-white).
logo = imread('logo.png');
%Grabbing the size of the image%
[Image_Height,Image_Width,~]= size(logo);
for Row = 1: Image_Height
for Column = 1: Image_Width
%Grabbing RGB pixel%
RGB_Pixel = logo(Row,Column,:);
if(~ismember(255,RGB_Pixel))
%RGB pixel is white change
logo(Row,Column,:) = 255;
else
%RGB pixel is coloured change to black%
logo(Row,Column,:) = 0;
end
end
end
imshow(logo);
Using the repmat() function is also a great solution that the above comment suggested. Which possibly may be the quickest method since you already have the code that generates one layer from the greyscale image.
Ran using MATLAB R2019b
I'm trying to color code some parameter values on a gray image in MATLAB. I'm wondering how to show gray image, make parameter values colored on the gray appearance image and on some pixels, and finally draw a colorbar aside the image just showing parameter values range.
Unsuccessful Code since now:
I = Igray; % gray image
Icc = zeros(size(I,1),size(I,2),3); % color coded image
Icc(:,:,1) = I;
Icc(:,:,2) = I;
Icc(:,:,3) = I;
Icc('some address in the image',3) = 'some number between 0 and 255';
imshow(Icc,[])
colorbar % colorbar showing colored parts spectrum
Result image that I need:
Try something like this:
I = Igray; % gray image
RGB = [1.0,0.7,0.2]; % color for patch
x = 30:50;
y = 70:90;
% If you gray image is in the range [0,255], make it range [0,1]
I = double(I)/255;
Icc = repmat(I,[1,1,3]);
block = I(y,x);
Icc(y,x,1) = 1 - ((1-block) * (1-RGB(1)));
Icc(y,x,2) = 1 - ((1-block) * (1-RGB(2)));
Icc(y,x,3) = 1 - ((1-block) * (1-RGB(3)));
imshow(Icc)
I'm sure there is a prettier way to encode this, but this way it shows the intent.
You're basically multiplying the grey values with the RGB color you want to make the patch. By inverting the patch and the color first, and inverting the result, the multiplication makes the patch brighter, not darker. That way you get the effect you want where the dark parts show the color also. If you multiply directly without inverting first, black stays black and doesn't show the color.
You'll have to figure out how to coordinate with the color bar after that. There are commands in MATLAB to set the limits of the color bar, you can find those reading the documentation.
The color bar you show uses the PARULA color map. You could do this to find the right RGB value to color your patch:
T; % value to color your patch in, in range [0,1]
cm = parula(256);
RGB = interp1(cm,T*255,'linear')
I need to remove horizontal and vertical lines in a binary image. Is there any method for filtering these lines? bwareaopen() is not good method to remove these lines and also Dilation and Erosion are not good for these cases.
Does any one know a solution?
Example image:
EDIT:(added more example images:
http://s1.upload7.ir/downloads/pPqTDnmsmjHUGTEpbwnksf3uUkzncDwr/example%202.png
source file of images:
https://www.dropbox.com/sh/tamcdqk244ktoyp/AAAuxkmYgBkB8erNS9SajkGVa?dl=0
www.directexe.com/9cg/pics.rar
Use regionprops and remove regions with high eccentricity (meaning the region is long and thin) and orientation near 0 or near 90 degrees (regions which are vertical or horizontal).
Code:
img = im2double(rgb2gray(imread('removelines.jpg')));
mask = ~im2bw(img);
rp = regionprops(mask, 'PixelIdxList', 'Eccentricity', 'Orientation');
% Get high eccentricity and orientations at 90 and 0 degrees
rp = rp([rp.Eccentricity] > 0.95 & (abs([rp.Orientation]) < 2 | abs([rp.Orientation]) > 88));
mask(vertcat(rp.PixelIdxList)) = false;
imshow(mask);
Output:
If all of your images are the same where the horizontal and vertical lines are touching the border, a simple call to imclearborder will do the trick. imclearborder removes any object pixels that are touching the borders of the image. You'll need to invert the image so that the characters are white and the background is dark, then reinvert back, but I'm assuming that isn't an issue. However, to be sure that none of the actual characters get removed because they may also be touching the border, it may be prudent to artificially pad the top border of the image with a single pixel thickness, clear the border, then recrop.
im = imread('http://i.stack.imgur.com/L1hUa.jpg'); %// Read image directly from StackOverflow
im = ~im2bw(im); %// Convert to black and white and invert
im_pad = zeros(size(im,1)+1, size(im,2)) == 1; %// Pad the image too with a single pixel border
im_pad(2:end,:) = im;
out = ~imclearborder(im_pad); %// Clear border pixels then reinvert
out = out(2:end,:); %// Crop out padded pixels
imshow(out); %// Show image
We get this:
You can firstly find the horizontal and vertical lines. Since, the edge map will also be binary so you can perform a logical subtraction operation in between the images. To find vertical lines, you can use (in MATLAB)
BW = edge(I,'sobel','vertical');
For horizontal lines, you can use
% Generate horizontal edge emphasis kernel
h = fspecial('sobel');
% invert kernel to detect vertical edges
h = h';
J = imfilter(I,h);
I have imported an image in matlab and before I display it how would I make the background of the image transparent? For example I have a red ball on a white background, how would i make the white pixels of the image tranparent so that only the red ball is visible and the white pixels are transparent?
You need to make sure the image is saved in the 'png' format. Then you can use the 'Alpha' parameter of a png file, which is a matrix that specifies the transparency of each pixel individually. It is essentially a boolean matrix that is 1 if the pixel is transparent, and 0 if not. This can be done easily with a for loop as long as the color that you want to be transparent is always the same value (i.e. 255 for uint8). If it is not always the same value then you could define a threshold, or range of values, where that pixel would be transparent.
Update :
First generate the alpha matrix by iterating through the image and (assuming you set white to be transparent) whenever the pixel is white, set the alpha matrix at that pixel as 1.
# X is your image
[M,N] = size(X);
# Assign A as zero
A = zeros(M,N);
# Iterate through X, to assign A
for i=1:M
for j=1:N
if(X(i,j) == 255) # Assuming uint8, 255 would be white
A(i,j) = 1; # Assign 1 to transparent color(white)
end
end
end
Then use this newly created alpha matrix (A) to save the image as a ".png"
imwrite(X,'your_image.png','Alpha',A);
Note for loops in MATLAB should be avoided at all costs because they are slow. Rewriting code to remove the loops is commonly referred to as "vectorizing" code. In the case of ademing2's answer, it could be done as follows:
A = zeros(size(X));
A(X == 255) = 1;
I'm writing code in which I use MATLAB's fill command to plot 2D shapes. I can specify the fill color of the shape. However, the border line color is always black. I want the border line color the same as the fill color. How can I also specify the border line color?
See this thread:
To set the edgecolor to white do the following.
h = fill([-1 -1 1 1],[-1 1 1 -1],'w');
axis([-2 2 -2 2]);
set(h,'edgecolor','white');
that should take care of the border.
In addition to schnaader's answer, you can also set the edge color in the initial call to FILL:
hPatch = fill(xData,yData,'r','EdgeColor','r'); %# Red patch with red edges
Or stop the edges from being drawn altogether:
hPatch = fill(xData,yData,'r','EdgeColor','none'); %# Red patch with no edges