What functions/commands can I use to smooth only a part of my curve? Lets say I have data from x= 0 to x= 500 on the x-axis with corresponding y points. I would like to smooth only data between x= 200 to x= 400, and the rest to be the original data itself. So that sharp edges between x= 0 and x= 200 remains, and then between x= 200 to 400, I get a smooth curve part, and then beyond x= 400 it retains the original shape. There was nothing I could find that would let me smoothen only a part of my curve.
Could someone please help me on this one?
Best regards,
Anirudh
You may wish to specify which language you are using to code?
This page contains some pointers. Also see this answer.
Related
I am trying to figure out an algorithm for detecting the free surface from a PIV image (see attached). The major problem is that in the flow under consideration gas bubbles are injected into the fluid, these rise up due to buoyancy and tend to sit on top of the surface. I don't want these to be mistaken for the free surface (actually want the '2nd' edge underneath them) - I'm struggling to figure out how to include that in the algorithm.
Ideally, I want an array of x and y values representing coordinates of the free surface (like a continuous, smooth curve).
My initial approach was to scan the picture left to right, one column at a time, find an edge, move to the next column etc... That works somewhat ok, but fails as soon as the bubbles appear and my 'edge' splits in two. So I am wondering if there is some more sophisticated way of going about it.
If anybody have any expertise in the area of image processing/edge detection, any advice would be greatly appreciated.
Typical PIV image
Desired outcome
I think you can actually solve the problem by using morphologic methods.
A = imread('./MATLAB/ZBhAM.jpg');
figure;
subplot 131;
imshow(A)
subplot 132;
B = double(A(:,:,1));
B = B/255;
B = im2bw(B, 0.1);
imshow(B);
subplot 133;
st = strel('diamond', 5);
B = imerode(B, st);
B = imdilate(B, st);
B = imshow(B);
This gives the following result:
As you can see this approach is not perfect mostly because I picked a random value for the threshold in im2bw, if you use an adaptive threshold for the different column of your images you should have something better.
Try to work on your lighting otherwise.
I want to plot only one simple set of data. For example, my plot command could be :
x = (1:10);
y = ones[1,10];
plot(x,y);
In fact, the y data set could have been generated by a previous code, depending on several parameters. I want to print the name of every parameters and there values outside the graph, at the right of it, as if it were a legend. My problem is that I have several parameters to print, but only one set of data.
I tried to do this by the text or legend functions, but it never fit completly my needs.
Could you help me please ?
I think this code should help you out. Its probably easiest to split your figure into two axes, the right one just to hold text:
x = rand(1,10);
y = rand(1,10);
figure % makes your figure
axes('Position', [0.05,0.05,0.45,.9]) % makes axes on left side of your figure
scatter(x,y)
axes('Position', [0.55,0,1,1],'ytick',[],'xtick',[]) %make axes on left side of your figure, turns of ticks
text(0.05,0.85,{'Parameter 1: blah blah';'Parameter 2: bloop bloop';'Parameter 3: ....'},'Interpreter','Latex')
Play around with the numbers in the brackets to resize things as you like.
I am trying to map my image point by point to 3 dimensional space.
For example, if my original image has intensity of 100 at location X, I want to plot this point in 3D location Y with intensity of 100. I want to repeat this steps for every point/pixel, and get a final image. My biggest problem is that I want to do it point by point.
I appreciate any comments or advice. Thank you.
=======================
p.s.
As I was writing this question, I just came up with an idea. I know how to print 'whole' image into certain location/shape in 3D by using warp() function. Instead of using my whole image as an argument to warp function, if I give one point intensity value and one 3D point as arguments for warp function, and repeat this steps for every image point, will I get a descent looking final image in 3D? If there is a better function to use, please let me know.
Sounds like you are looking for scatter3:
I = imread('cameraman.tif');
[x y]=meshgrid(1:size(I,1), 1:size(I,2));
scatter3(x(:),y(:),I(:),15,I(:),'filled');
axis tight; colormap gray
And this is what you get (after some changes to view point):
PS,
I used a single scatter3 command to plot all the points at once. You may (I have no idea why you would like to do so) do it one by one
figure;
for ii=1:numel(x)
scatter( x(ii), y(ii), I(ii), 15, I(ii), 'filled');
hold on; % need this!
end
axis tight; colormap gray;
I am trying to create a graph based on Mike Bostock's Heirarchical Edge Bundling(here is the gist). I need to make my JSON look as readme-flare-imports.json looks, but I can't figure out what "size" is. I read the API and it didn't seem to help me. Also, it will be a dynamic JSON file based on a mySQL database, so I won't be able to set the size myself. Is anybody able to clear things up for me as to what it is or how I may be able to determine what the size should be? Thank you in advance!
cluster.size determines how large of an area the cluster will take up. You pass values to it like so
// The angle
var x = 360;
// The radius
var y = window.height / 2;
cluster.size([x, y])
x will determine how much of a circle the cluster will use to branch out children. A value of 360 will use the entire circle to display all values. A value of 180 will only use half the circle to branch out values.
y will determine how wide the circle will become in any single direction, i.e., the radius of the circle.
In the Heirarchical Edge Bundling example, I believe the size attribute in the json file is ignored as I could not find anything in the code that cared about it.
I am going to prepare my assignment. It's a bit freaky as our Teacher, though :D. Okay, the job is simple. There will be a white cloth vertically. A person will be in front of that. Distance of the man from the cloth is 3 feet. The shadow of the person will be caught through a mid res (say 1600 X 1200) camera. The image (img01.jpg) of this camera is my input. I have to measure the man's body from the image, I mean parts of body. I need 80 to 90 percent accuracy. Desired output is some length (centimeter):
A = ?
B = ?
C = ?
D = ?
E = ?
Just as the picture:
I don't know what type of algorithm is needed here and I don't want to ask it to my freaky Sir. Great hearts here are requested to help me. Do not ask me for my code as I don't have yet. I don't need codes rather I need algorithms to do the job.
Thanks in advance.
Find the number of pixels between the points and multiply by the number of cm's per pixel based on how far the subject is from the camera.
A possible algorithm would be, given a vertical offset y, to find the distance (in pixels) between the first colored (or in your case, black) pixel and the last one, on the same line y. Then, you can use your unit conversion as you deem convenient, once you fix the scale between pixels and your real world measure. This answer would work assuming, as in your example, that the distance is measured horizontally and not diagonally on the figure.