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Possible to select all "disparate" pixels? (cs4, M

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Old 08-05-2011, 11:23 PM
jane255 jane255 is offline
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Possible to select all "disparate" pixels? (cs4, M

Is it possible to select all of the pixels that are very different from the ones around it? I know about the noise filter, but so far I haven't been able to set it to do exactly what I'd like to do:

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Old 08-06-2011, 11:30 AM
John Wheeler's Avatar
John Wheeler John Wheeler is offline
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Re: Possible to select all "disparate" pixels? (cs

Hi Jane and welcome to the forums
Depending on the specifics, there may be ways to do what you want. However, it depends on the specifics of what you mean by "very different" from the pixels around it e.g.

- very different in luminosity, color, or both
- different from a fixed color background or just arbitrarily different from surrounding random pixels
- How different is different - do you need a variable control on this
- What pixel width defines what you want to select vs eliminate (e.g. is anything that is 2 pixels width or less OK to assume you want identified?)
- Do you need this to be exact or just approximate.
- Are the cases you show in your image two separate needs (e.g single pixels vs string of single pixels?)

In the example you gave, it seems that the background is constant and white (solid non-varying color). Also, all the objects you want to "keep?" look like they are at least 3 pixels wide somewhere in the object). If that is always the case for you needs. If this is the case you need to cover (or similar) I think I have a solution for you. Just need some more details.
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Old 08-06-2011, 04:26 PM
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John Wheeler John Wheeler is offline
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Re: Possible to select all "disparate" pixels? (cs

Here are some example steps of identifying and then eliminating the outlying pixels. First, here is the image I leveraged from you as a starting point:

Find Pixel 1.png

- First step is to use magic wand with no anti alias and tolerance set to 0 and select the background of just white
- Invert the selection to choose all non-background pixels (see image)

Find Pixel 2.png

- Create a empty layer
- Fill selection with black
- Contract Selection by 1 pixel (see image)

Find Pixel 3.png

- With Black Layer still active Grow Selection by 1 pixel
- Click eye icon on Layer Panel to hide black layer
- Selection should now just be around the non disparate pixels of your original image (see image)

Find Pixel 4.png

- Invert Selection
- Fill with white
- Deselect selection
- This has eliminated all disparate pixels (see image)

Find Pixel 5.png

This should give you some ideas on how to approach one type of problem of the nature in which you have interest. Hope that helps.
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