# Revision history [back]

### How to detect crescent shape?

Hi,

How can I detect a crescent shape? I have a binary image where the crescent is in white and the rest is black. There could be some noise and other shape in the image too. I tried with Hough circle but since it's not a complete circle, it detect other circle from the noise instead of the one in the crescent.

I was thinking about using shape comparison with contour but since a crescent is a complex polygon, I'm not sure it will work.

Any ideas on how to approach this problem?

### How to detect crescent shape?

Hi,

How can I detect a crescent shape? I have a binary image where the crescent is in white and the rest is black. There could be some noise and other shape in the image too. I tried with Hough circle but since it's not a complete circle, it detect other circle from the noise instead of the one in the crescent.

I was thinking about using shape comparison with contour but since a crescent is a complex polygon, I'm not sure it will work.

Here is an example:

Any ideas on how to approach this problem?

### How to detect crescent shape?

Hi,

How can I detect a crescent shape? I have a binary image where the crescent is in white and the rest is black. There could be some noise and other shape in the image too. I tried with Hough circle but since it's not a complete circle, it detect other circle from the noise instead of the one in the crescent.

I was thinking about using shape comparison with contour but since a crescent is a complex polygon, I'm not sure it will work.

Here is an example:

Any ideas on how to approach this problem?

### How to detect crescent shape?

Hi,

How can I detect a crescent shape? I have a binary image where the crescent is in white and the rest is black. There could be some noise and other shape in the image too. I tried with Hough circle but since it's not a complete circle, it detect other circle from the noise instead of the one in the crescent.

I was thinking about using shape comparison with contour but since a crescent is a complex polygon, I'm not sure it will work.

Here is an example:

Any ideas on how to approach this problem?

EDIT

I know how to dilate and erode the image above to get a cleaner image. What I'm interested in is how to detect that it's a crescent.