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Re: measuring grayscale of objects in a plate

Posted by JDing on Jul 26, 2013; 10:14pm
URL: http://imagej.273.s1.nabble.com/measuring-grayscale-of-objects-in-a-plate-tp5004160p5004166.html

I am confused about what "your ROIs" means. Do you mean 1) the ROI set that I have saved, which has one ROI for each of the 48 wells, or 2) the ROIs that I get after I threshold/analyze particles/save to ROI manager?

If you mean (1), my saved ROI set has ROIs that includes each well in its entirety. However, since seeds take up only a fraction of the well, and since seeds can be in many different shapes and sizes and places within the well, my ROI set doesn't actually help very much in identifying the seeds themselves. In my original post, I suggested that if I could apply the threshold/analyze particle functions to only the ROI and not the entire image, then I could apply the process 48 times, one time for each ROI/well, which would then be in order, since my ROI set is already in order, and I do this in the order of my ROI set. However, I do not know how to apply the functions to only the ROI, so I can't use this method (unless you know how to do it).

If you mean (2), the seeds vary in position within each well. So even though in theory, if I tell the program to list in increasing y-coordinate values and then in increasing x-coordinate values, I should get the wells/seeds in order, this is not the case in practice. This is what I tried to explain in my previous post. Unless I am misunderstanding you, in which case you would have to explain your method in slightly more detail.

Thanks

JDing


On Fri, Jul 26, 2013 at 4:09 PM, Karsten Rodenacker-3 [via ImageJ] <[hidden email]> wrote:
Assuming your wells build a chequerboard and the image is aligned with it, the coordinates of your ROIs will allow the ordering of the results. Of course the actual list of result entries depend on the sequence of your ROIs in the ROI manager rspw. on the first found pixel per region.

Possibly you have to load the results into Excel or R for the ordering in x and y.

Regards
Karsten

Am 26.07.2013 um 22:55 schrieb JDing <[hidden email]>:

> You understand me correctly, but your suggestion doesn't seem to work. I
> added "center of mass" to the measurements and it didn't put the wells in
> order. Here is my explanation: even though the sides of my plate are aligned
> with the x and y axes, the seeds themselves vary in their position within
> the well (and their size). So the seed in A1 could be centered at coordinate
> (50, 50), while B1 is at (100, 49), and C1 is at (150, 49.5), etc. In this
> case, if ImageJ measured/listed in order of increasing y-coordinate (the
> default for my computer), it would list B1 and C1 before A1. So this method
> doesn't work well in real practice.
>
> Thank you for your consideration, though.
>
> JDing
>
>
>
> --
> View this message in context: http://imagej.1557.x6.nabble.com/measuring-grayscale-of-objects-in-a-plate-tp5004160p5004163.html

> Sent from the ImageJ mailing list archive at Nabble.com.
>
> --
> ImageJ mailing list: http://imagej.nih.gov/ij/list.html

Karsten
[hidden email]

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