color-coded optical flow image

2016 1 9
1 个回答
更新时间：2016 1 10
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Background: main task is segmentation and tracking of (multiple) objects in a video, i intend to use meanshift for segmentation to which LUV-color-coded optical flow image is to be used as input.
So i calculated optical flow and converted vertical and horizontal values to polar coordinates using cart2pol. Now used Image Analyst's colorwheel and used following code to obtain RGB-color-coded optical flow image.
%%accessing RGB color agains theta and rho
outDir='./output/';
load([outDir 'polarflow.mat']);
rgbflow=struct('rgb_flow',{});
for i=1:size(polarflow,2)
for row=1:size(polarflow(1).p_flow,1)
for col=1:size(polarflow(1).p_flow,2)
theta=polarflow(i).p_flow(row,col,1);
theta_in_degrees = radtodeg(theta);
theta_in_degrees = ceil(wrapTo360(theta_in_degrees));
rho=ceil(polarflow(i).p_flow(row,col,2));
% colour_row = ceil(size(rgb,1) * theta_in_degrees/359 + eps);
% colour = rgb(colour_row,:); %%these 2 lines return 1755 values, couldn't interpret
colour=rgb(theta_in_degrees,rho,:);
rgbflow(i).rgb_flow(row,col,1)=colour(:,:,1);
rgbflow(i).rgb_flow(row,col,2)=colour(:,:,2);
rgbflow(i).rgb_flow(row,col,3)=colour(:,:,3);
end
end
end
save([outDir 'rgbflow.mat'],'rgbflow');
Problem is only a portion of original image is left, much foreground information is lost. An image and result image is attached. Kindly let me know any tips.

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回答（1 个）

Image Analyst
Image Analyst 2016-1-9

0 个投票

There are several color pickers in the File Exchange: http://www.mathworks.com/matlabcentral/fileexchange/?search_submit=fileexchange&query=color+picker&term=color+picker
Or you can adapt my attached color wheel demo to use ginput() to let the user pick the color they want to use.

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Maryam Butt
Maryam Butt 2016-1-9
Thank you for help, kindly clear one more thing when i use Star Strider's code it returns (r,g,b) value for colour for any value of theta while using that code with your color_wheel returns a row of 1755 columns, how to interpret this?
Image Analyst
Image Analyst 2016-1-9
You can get the row and column from ginput, something like
[x,y] = ginput(1);
row = round(y);
col = round(x);
theColor = rgbImage(row, col, :);
Maryam Butt
Maryam Butt 2016-1-9
ginput isn't necessary because i have all x,y values which I need to convert to polar coordinates (done) then i have got polar values [theta,rho] now i need to access the color value corresponding to theta angle and also incorporate rho somehow.
Image Analyst
Image Analyst 2016-1-10
I'm not sure what you're after with your latest edit, but if you want to track green blobs, see my attached demo.
Maryam Butt
Maryam Butt 2016-1-10
Though in this image green blobs (basketball) need to be tracked but it is only an example, I want to track moving objects in general, they can be of any color, shape etc.
Image Analyst
Image Analyst 2016-1-10
Usually they just use quiver to show arrows. If you want them in colors for different vector lengths, you'd have to look for code for that. I think I've seen it but I don't remember where.

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