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number of measurement exceeds 700


hannan

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Hi there,

I am trying to understand how PS makes it´s area measurements. I have images of pink algal crusts on a black surface and I use colour selection to select them. When I want to use the "make measurement" function I will get the warning that the number of counts exceeds 700. So here is the question is there a way to exclude areas under a certain size. If not does anybody here know how the area measurements are made. The list seems to be a pretty random mix of high and low values. If it would only select the 700 largest areas it would be pretty sufficient for me as a lot of the selected areas are few pixel spots where colours fade etc. It would be immensely helpful if somebody of you professionals out there has some advice for me.
Cheers,
Anna
 

fredfish

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Hi Anna Welcome to the forum.

I am not going to even pretend to have any specific knowledge in this area. However just in case it has passed you by have you seen this section on the Adobe Help pages (I suspect that you have - this is just in case). https://helpx.adobe.com/photoshop/using/measurement.html

Cheers

John
 

MrToM

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Upgrade to Photoshop CC, the maximum amount of measurements is in the thousands.

If that isn't an option then you could split the image up into manageable chunks and measure it that way...if a chunk results in more than 700 results then split that chunk in half until its below 700.

Repeat until you have measured the whole image.

Divide and conquer!

Regards.
MrToM.
 
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thebestcpu

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Hi Anna

I will second the recommendation to review the help file. Note that you can set a custom scale for the measurement to have the numbers represent whatever you want. The default is that the area is simply the total number of pixels within the Marching ants selection area for any given complete area selected.

The selection tool creates a selection with a soft edge so you want to make sure that you are selecting all of the desired color areas. You could also consider using the magic wand tool with the feather set to zero for a sharper edge

If you have a lot of areas that have a dimension of only a couple pixels or so, there is a workaround you could try to reduce the number of objects.

1) Once you have created your selection, use the Select > Modify> Contract by e.g. 1 or 2 pixels. The smallest selections will disappear
2) Then you increase the size of the selection by either
a) Select > Modify > Expand by the same number of pixels you contracted the selection or
b) Use the Select > Grow command to increase the remaining selections to include the same adjacent colors.

Using the above approach, all the very small selections will be eliminated. This approach is not perfect because it is based on a linear dimension for elimination and not area. Therefore a long narrow area could also be eliminated.

Thought it was worth mentioning as an approach to consider

John Wheeler
 

hannan

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Hi and many thanks to you all for helping me!
@MrToM, thanks for your suggestions. Unfortunately an upgrade is not really an option at this point in time. Sure I have tried with splitting the analysis into several parts, but it is very time consuming. thebestcpu your suggestion to reduce the selection and adding pixels to the remaining selection is actually a really good work around. It does need careful monitoring, but works quite efficiently to get rid of the small selections. I think this will work for me. I´ll run a couple of trials to test the method.

Thank you very much. You´ll probably hear from me and my algae soon again.
Anna
 
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