clc;clf;i=imread('AB_1-16_pH_7.jpg');subplot(421);imshow(i);title('orginalimage');j=rgb2gray(i);subplot(422);imshow(j);title('grayimage');subplot(423);m=edge(j,'canny');imshow(11);title('edge with canny function');subplot(424);figure(2)m=imread('AB_1-16_pH_7.jpg');imshow(m);title('base image');MATLAB: Is the image appearing all white? I am trying to detect its edges with the following code..
edge detectionImage Processing Toolbox
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Convert to grayscale and then threshold and find the bounding box
clc; % Clear the command window.
close all; % Close all figures (except those of imtool.)
imtool close all; % Close all imtool figures.
clear; % Erase all existing variables. Or clearvars if you want.
workspace; % Make sure the workspace panel is showing.
format long g;format compact;fontSize = 20;% Read in the color image.
folder = pwd;baseFileName = 'm2.bmp';% Get the full filename, with path prepended.
fullFileName = fullfile(folder, baseFileName);if ~exist(fullFileName, 'file') % Didn't find it there. Check the search path for it.
fullFileName = baseFileName; % No path this time.
if ~exist(fullFileName, 'file') % Still didn't find it. Alert user.
errorMessage = sprintf('Error: %s does not exist.', fullFileName); uiwait(warndlg(errorMessage)); return; endendrgbImage = imread(fullFileName);% Get the dimensions of the image. numberOfColorBands should be = 3.
[rows, columns, numberOfColorBands] = size(rgbImage);% Display the original color image.
subplot(2, 3, 1);imshow(rgbImage, []);axis on;title('Original Color Image', 'FontSize', fontSize);drawnow;% Enlarge figure to full screen.
set(gcf, 'units','normalized','outerposition',[0 0 1 1]);% Histogram the red channel, but there is a huge spike at 255 so let's not count those.
subplot(2, 3, 2);grayImage = rgb2gray(rgbImage);imshow(grayImage, []);title('Gray Scale version', 'FontSize', fontSize);subplot(2, 3, 3);histogram(grayImage(grayImage<255))grid on;title('Histogram of Gray Scale Image', 'FontSize', fontSize);someThresholdValue = 150;binaryImage = grayImage > someThresholdValue;% Take largest blob
binaryImage = bwareafilt(binaryImage, 1);subplot(2, 3, 4);imshow(binaryImage);grid on;title('Binary Image', 'FontSize', fontSize);% Label the binary image.
labeledImage = bwlabel(binaryImage);props = regionprops(labeledImage, 'BoundingBox');bbox = props.BoundingBoxcroppedImageRGB = imcrop(rgbImage, bbox);subplot(2, 3, 5);imshow(croppedImageRGB);grid on;title('Cropped RGB Image', 'FontSize', fontSize);% Gray scale version of cropped image
croppedImageGray = imcrop(grayImage, bbox);subplot(2, 3, 6);imshow(croppedImageGray);grid on;title('Cropped Gray Scale Image', 'FontSize', fontSize);
Use axis('on', 'image'). I fixed other problems too. Fixed code is below:
clc;clear all;close all;workspace; % Make sure the workspace panel is showing.
% Read in original RGB image.
rgbImage = imread('Table.jpg');subplot(2, 2, 1);imshow(rgbImage)axis('on', 'image');title('Original Image')% Convert to gray scale.
grayImage = rgb2gray(rgbImage);subplot(2, 2, 2);imshow(grayImage)axis('on', 'image');title('Grey Scale Image')% Get edges
Canny_img = edge(grayImage, 'Canny');subplot(2, 2, 3);imshow(Canny_img, [])axis('on', 'image');title('Edge Detected Image')% Enlarge figure to full screen.
set(gcf, 'Units', 'Normalized', 'Outerposition', [0, 0.05, 1, 0.95]);
By the way, you don't need to do edge detection to "find" the table if that's all that you want to do. You can simply threshold.
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