MATLAB Answers

imbinarize not working on given image

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SURBHI GOEL on 1 Nov 2020
Commented: SURBHI GOEL on 1 Nov 2020
So I have attached the image of coins I am using. I need to make this image black and white but it's just showing an area whole filled with white. When I run on coins.tif file provided in MATLAB, my code works fine but not on this image. Please tell me where I am going wrong. TIA
Image = imread('Coin.jpg');
[rows, columns, numberOfColorBands] = size(Image);
if numberOfColorBands > 1
grayImage = rgb2gray(Image);
grayImage = Image;
set(gcf, 'units','normalized','outerposition',[0 0 1 1]);
binaryImage = imbinarize(grayImage);
subplot(3, 1, 1);
imshow(Image, []);
subplot(3, 1, 2);
imshow(grayImage, []);
subplot(3, 1, 3);
imshow(binaryImage, []);
The best binary image I could get is by using this line
binaryImage = imbinarize(grayImage,'adaptive','ForegroundPolarity','bright','Sensitivity',0.13);
But still I am getting numerous white dots here and there in the black area like this.

Accepted Answer

drummer on 1 Nov 2020
Edited: drummer on 1 Nov 2020
by using size, you're obtaining the dimension information of the image. So your 3rd coordinate (numberOfColorBands) would be the position in the stack (of a volumetric image), and not the # channels of your image.
Try using
info = imfinfo('yourImage')
% Then, use info in your if condition.
SURBHI GOEL on 1 Nov 2020
Thanks a lot. Erosion worked.

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