Convert red portion to white and the background to black . Second part is to detect road sign and put bounding box on it.

I need to extract the road sign from an image. Can someone help me with this as I am new to matlab.

Answer 1

[Image Analyst]

Try the Color Thresholder on the Apps tab of the tool ribbon. Otherwise look in the Computer Vision Toolbox or Automated Driving Toolbox for road sign demos.

[renit anthony]

I am finding it difficult to extract road signs which have noise in it. But somehow for extracting yellow road signs with lot of noise with this code was possible.

This was the code for yellow .

clc;

close all;

tic;

IORG=dir('C:\Users\Renit\Desktop\vijaycode (copy)\QBDSONN\dest\*.jpg');

for i=1:length(IORG)

filename=strcat('C:\Users\Renit\Desktop\vijaycode (copy)\QBDSONN\dest\',IORG(i).name);

I=imread(filename);

J = rgb2ycbcr(I);

CB = J(:,:,2);

histCB = imhist(CB)/numel(CB);

CCB = zeros(size(histCB));

for j = 1:length(CCB)

CCB(j) = sum(histCB(1:j));

end

inx = find(CCB < 0.01,1,'last');

B = CB <= inx-1;

figure,imshow(B);

p=strcat('C:\Users\Renit\Desktop\vijaycode (copy)\save\',IORG(i).name);

imwrite(B,p)

end

timeElapsed = toc

In this i tried to change it for red also but I don't know why it isnt working

[Image Analyst]

Looks like you didn't try my suggestion. If you had, you would have ended up with something like this:

% Demo to find road signs.  By Image Analyst, Sep 18, 2020.
clc;    % Clear the command window.
close all;  % Close all figures (except those of imtool.)
clearvars;
workspace;  % Make sure the workspace panel is showing.
format long g;
format compact;
fontSize = 16;
fprintf('Beginning to run %s.m ...\n', mfilename);

%-----------------------------------------------------------------------------------------------------------------------------------
% Read in image.
folder = [];
baseFileName = 'double.jpg';
fullFileName = fullfile(folder, baseFileName);
% Check if file exists.
if ~exist(fullFileName, 'file')
	% The file doesn't exist -- didn't find it there in that folder.
	% Check the entire search path (other folders) for the file by stripping off the folder.
	fullFileNameOnSearchPath = baseFileName; % No path this time.
	if ~exist(fullFileNameOnSearchPath, 'file')
		% Still didn't find it.  Alert user.
		errorMessage = sprintf('Error: %s does not exist in the search path folders.', fullFileName);
		uiwait(warndlg(errorMessage));
		return;
	end
end
rgbImage = imread(fullFileName);
[rows, columns, numberOfColorChannels] = size(rgbImage)
% Display the test image.
subplot(2, 2, 1);
imshow(rgbImage, []);
axis('on', 'image');
caption = sprintf('Image : "%s"', baseFileName);
title(caption, 'FontSize', fontSize, 'Interpreter', 'None');
drawnow;
hp = impixelinfo(); % Set up status line to see values when you mouse over the image.

% Set up figure properties:
% Enlarge figure to full screen.
hFig1 = gcf;
hFig1.Units = 'Normalized';
hFig1.WindowState = 'maximized';
% Get rid of tool bar and pulldown menus that are along top of figure.
% set(gcf, 'Toolbar', 'none', 'Menu', 'none');
% Give a name to the title bar.
hFig1.Name = 'Demo by Image Analyst';

% Get red stuff
[mask, maskedRGBImage] = createMask(rgbImage);

% Display the initial mask image.
subplot(2, 2, 2);
imshow(mask, []);
axis('on', 'image');
title('Initial Color Segmentation Mask', 'FontSize', fontSize, 'Interpreter', 'None');
drawnow;

% Fill holes
mask = imfill(mask, 'holes');
props = regionprops(mask, 'area');
allAreas = sort([props.Area], 'descend')
% Get rid of small blobs less than 1000 pixels in area.
mask = bwareaopen(mask, 1000);
% Display the final mask image.
subplot(2, 2, 3);
imshow(mask, []);
axis('on', 'image');
title('Final Road Sign Mask', 'FontSize', fontSize, 'Interpreter', 'None');
drawnow;
hp = impixelinfo(); % Set up status line to see values when you mouse over the image.

% Mask the image using bsxfun() function to multiply the mask by each channel individually.  Works for gray scale as well as RGB Color images.
maskedRgbImage = bsxfun(@times, rgbImage, cast(mask, 'like', rgbImage));

% Display the final mask image.
subplot(2, 2, 4);
imshow(maskedRgbImage, []);
axis('on', 'image');
title('Final Masked Red Road Sign', 'FontSize', fontSize, 'Interpreter', 'None');
drawnow;
hp = impixelinfo(); % Set up status line to see values when you mouse over the image.


function [BW,maskedRGBImage] = createMask(RGB)
%createMask  Threshold RGB image using auto-generated code from colorThresholder app.
%  [BW,MASKEDRGBIMAGE] = createMask(RGB) thresholds image RGB using
%  auto-generated code from the colorThresholder app. The colorspace and
%  range for each channel of the colorspace were set within the app. The
%  segmentation mask is returned in BW, and a composite of the mask and
%  original RGB images is returned in maskedRGBImage.

% Auto-generated by colorThresholder app on 18-Sep-2020
%------------------------------------------------------


% Convert RGB image to chosen color space
I = rgb2hsv(RGB);

% Define thresholds for channel 1 based on histogram settings
channel1Min = 0.980;
channel1Max = 0.057;

% Define thresholds for channel 2 based on histogram settings
channel2Min = 0.210;
channel2Max = 1.000;

% Define thresholds for channel 3 based on histogram settings
channel3Min = 0.367;
channel3Max = 0.679;

% Create mask based on chosen histogram thresholds
sliderBW = ( (I(:,:,1) >= channel1Min) | (I(:,:,1) <= channel1Max) ) & ...
	(I(:,:,2) >= channel2Min ) & (I(:,:,2) <= channel2Max) & ...
	(I(:,:,3) >= channel3Min ) & (I(:,:,3) <= channel3Max);
BW = sliderBW;

% Initialize output masked image based on input image.
maskedRGBImage = RGB;

% Set background pixels where BW is false to zero.
maskedRGBImage(repmat(~BW,[1 1 3])) = 0;

end

Do the same for yellow but create a new masking function for yellow using the Color Thresholder.

[renit anthony]

Hi,

I am sorry but the above code is not detecting for this image. With little amount of noise added. Also I need to save it somwhere in my computer. I am not sure where to place imwrite for the last final masked red road sign ().

[Image Analyst]

You need to find thresholds for "red" that work for the entire range of "reds" that you expect to see. I made some adjustments using the Color Thresholder and it works fine. Not sure why are not even trying that app, but you really should.

[renit anthony]

Thank you so much. I will definitely try it out . Thank you for helping me out :)