C# breaking monochrome image down into new images.

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Discussion Overview

The discussion revolves around techniques for segmenting a monochrome image into separate bitmaps based on color values, specifically focusing on separating black and white "blobs" after applying edge detection and thresholding. The inquiry is aimed at understanding the underlying processes without relying on external libraries.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification

Main Points Raised

  • One participant seeks methods to segment an image into separate bitmaps based on color values, specifically separating black from white after applying edge detection and thresholding.
  • Another participant suggests that the process might be related to "masking," providing a link to a relevant Wikipedia page.
  • A different participant questions the need for separation, suggesting that a black and white image is already separated.
  • One participant proposes that the goal may involve cropping copies of the original image based on the locations of the blobs, mentioning terms like object extraction, image segmentation, and auto-cropping.
  • The original poster confirms that the proposed approach aligns with their goal, specifically needing to identify four edge points for cropping.

Areas of Agreement / Disagreement

Participants express varying interpretations of the original poster's request, with some confusion about the need for separation in a black and white image. While there is some agreement on the general approach to achieving the desired outcome, the specifics remain somewhat unclear.

Contextual Notes

There are unresolved aspects regarding the exact method for identifying the blobs and the process for cropping them based on edge points. The discussion does not clarify the definitions of terms used, such as "masking" and "image segmentation," which may depend on specific contexts.

Superposed_Cat
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Hi all, c# coder here, i am seeking ways to segment images into separate bitmaps based on colour values.

I have an image, and i have already applied edge detection and changed the threshold to 230 to give me black and white "blobs". Now the issue is finding these blobs, and copying them into separate bitmaps. Now I want to do this without external libraries as this is for me to understand how it works.

Every time I Google this I get a opencv or aforge link. Does anyone know of a link or a technique name? Note: it is not breaking it down to monochrome that I seek it is separating the black from the white.

Any help appreciated, thanks.
 
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It sounds like "masking" to me.
http://en.wikipedia.org/wiki/Mask_(computing )
 
Last edited by a moderator:
nice but not what I'm looking for. that combines to images, I'm looking to separate.
 
Superposed_Cat said:
nice but not what I'm looking for. that combines to images, I'm looking to separate.

I'm not sure I understand. If the image is already in black and white, isn't it technically already separated?
 
I don't know quite what you want, but I'm guessing that you want to crop copies of your original image based on where the blobs are in the filtered (edge-enhanced, high-contrast) image.

So, if I'm guessing correctly, your original picture has several relatively bright objects on a dark background. You apply the 230 contrast to create a mask of the object of interest, but you do an edge-enhancement first to keep the 230 contrast from trimming the objects too much.

Now you want to identify continuous white regions and draw rectangles around them so you can use those rectangles to crop copies of the original image.

Is this what you're trying to do?

-----
If I'm guessing right, the terms would be object extraction (which you have already done), image segmentation, and auto-cropping. Also, to some extent, "image detection".
 
Last edited:
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yes scott!thanks! that is what I want. but I need to get four edge points so I can crop them.
 

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