error using imsubtract

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Megah Putri
Megah Putri on 18 Aug 2011
I've been using imsubtract, i want to replace the background with black, but why that appear only in black ... no image object .. what is wrong ...?

Answers (3)

Alex Taylor
Alex Taylor on 12 Sep 2011
Megah,
I'd also recommend that you use the MATLAB minus operator instead of imsubtract to perform elementwise subtraction on two images:
image3 = im2double(image1) - im2double(image2)
The imadd and imsubtract functions are old and predate support for integer math in base MATLAB.
The MATLAB math operators are better maintained and in general will exhibit better performance:
>> a = rand(4000,4000); >> b = rand(4000,4000);
>> tic; for i = 1:100; imsubtract(a,b); end; toc
Elapsed time is 17.827151 seconds.
>> tic; for i = 1:100; a-b; end; toc
Elapsed time is 8.206314 seconds.
- Alex.

Wolfgang Schwanghart
Wolfgang Schwanghart on 18 Aug 2011
Hi Megah, apparently both variables don't have the same class. Try
image3 = imsubtract(im2double(image1),im2double(BWfinal))
[edited according to WRs suggestion]
  3 Comments
Megah Putri
Megah Putri on 18 Aug 2011
thank you wolfgang schwanghart,,, ^_^ ,,, thank you walter roberson ^_^

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Pramod Bhat
Pramod Bhat on 25 Aug 2011
convert them to the same class. both the images shud be in the same format.

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