Why I got error when I used Jaccard similarity coefficient?

I used the following aklgorithm to evaluate the jaccarrd index:

gT= imread('crack .png');

o=imread('outPut .png');

similarity = jaccard(o, gT)

figure

imshowpair(o, gT)

title(['Jaccard Index = ' num2str(similarity)])

but I got The following error message:

Error using jaccard

Expected input number 1, A, to be one of these types:

logical, double, categorical

Instead its type was uint8.

Error in

jaccard>@(x,name,pos)validateattributes(x,{'logical','double','categorical'},{'real','nonempty','nonsparse'},mfilename,name,pos)

(line 118)

validateInput = @(x,name,pos) validateattributes(x, ...

Error in jaccard (line 123)

validateInput(A,'A',1);

Error in Gtruth1 (line 21)

similarity = jaccard(o, gT)

Thus, how can i fix this error, especially I am new biggener in matlab and I am trying to evaluate the similarity between groundTruth image (crack.png) and the resulted image from my model (outPut.png)?

Answer 1

[Shreeya]

The jaccard function in MATLAB expectes the input argument images of type logical. The error thrown suggests that the images are of datatype uint8. The documentation linked below can help you understand the usage of the function:

https://www.mathworks.com/help/images/ref/jaccard.html#d126e218227

To convert the images to a logical format, you can use the code below:

gT_logical = gT > threshold;

This code is sourced from the following MATALB answer. You can refer to the discussion for more details:

https://www.mathworks.com/matlabcentral/answers/178621-how-to-convert-unit8-type-images-to-logical-type