How do I cut the black baground from this image?

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Arthur Pereira 2018-5-17

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https://ww2.mathworks.cn/matlabcentral/answers/401145-how-do-i-cut-the-black-baground-from-this-image

编辑： Florian Morsch 2018-5-18

Hello, I have passed a mask in a image but i want to remove the back blackground, I want to remove all the black pixels. How should I do this?

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Florian Morsch 2018-5-17

What do you mean by remove it? Do you want it white or do you want nothing at all?

Arthur Pereira 2018-5-17

I want nothing at all. Is that possible?

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Answer 1

Florian Morsch 2018-5-18

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https://ww2.mathworks.cn/matlabcentral/answers/401145-how-do-i-cut-the-black-baground-from-this-image#answer_320752

编辑：Florian Morsch 2018-5-18

You can change the alpha channel of the image to fit your needs. The real "problem" here is, there is no such thing as "nothing". If you turn the black to opaque you still have some kind of background color (mostly some grayish or so). You could also cut out the colored part and save it as new picture, this should also work.

https://de.mathworks.com/help/matlab/ref/alpha.html

https://blogs.mathworks.com/steve/2009/02/18/image-overlay-using-transparency/

https://de.mathworks.com/matlabcentral/answers/104889-how-to-overlay-a-foreground-image-over-a-background-image

These three links provide information and examples for the change in the alpha channel.

For cropping and saving the cropped part there are examples here: https://de.mathworks.com/matlabcentral/answers/315408-how-to-cropt-the-image-and-save-cropped-part