Area measurements with holes

[JoeML]

Hello everyone
This is the first time i write in this forum and i dont write english very well so i hope you can understand me and help me.
I want to measure the area in red, only the red area of this picture, so i have two questions:
1- When I select the area in imageJ is it calculated the area including the holes?
2- How can I calculate the area without the hole, ergo, only the sign in red?


Thank you very much

[Christian Tischer]

Hey Joe,

one way is to threshold the image

i) Image..Adjust..Threshold..Apply
ii) Select the region
iii) Analyze..Set Measurements...Integrated Density
iv) press M to measure the region and then divide the IntDen by 255

this basically counts the number of thresholded pixels in the region.

Tischi


On Mon, Sep 24, 2012 at 1:01 AM, JoeML <[hidden email]> wrote:

> Hello everyone
> This is the first time i write in this forum and i dont write english very
> well so i hope you can understand me and help me.
> I want to measure the area in red, only the red area of this picture, so i
> have two questions:
> 1- When I select the area in imageJ is it calculated the area including the
> holes?
> 2- How can I calculate the area without the hole, ergo, only the sign in
> red?
> <http://imagej.1557.n6.nabble.com/file/n5000166/Sin_t%C3%ADtulo.png>
>
> Thank you very much
>
>
>
> --
> View this message in context:
> http://imagej.1557.n6.nabble.com/Area-measurements-with-holes-tp5000166.html
> Sent from the ImageJ mailing list archive at Nabble.com.
>
> --
> ImageJ mailing list: http://imagej.nih.gov/ij/list.html
>

--
ImageJ mailing list: http://imagej.nih.gov/ij/list.html

[JoeML]

Thank you tischi
But i have another question,
Why I have to divide by 255?
Can i use the tool "include holes" to calculate the red area?

Thank you

[Christian Tischer]

the masks that you get from thresholding have 255 and 0 as pixel values.
for my method to work you need 1s and not 255s.
i don't understand your question regarding the "include holes"


On Mon, Sep 24, 2012 at 10:08 AM, JoeML <[hidden email]> wrote:

> Thank you tischi
> But i have another question,
> Why I have to divide by 255?
> Can i use the tool "include holes" to calculate the red area?
>
> Thank you
>
>
>
> --
> View this message in context:
> http://imagej.1557.n6.nabble.com/Area-measurements-with-holes-tp5000166p5000172.html
> Sent from the ImageJ mailing list archive at Nabble.com.
>
> --
> ImageJ mailing list: http://imagej.nih.gov/ij/list.html
>

--
ImageJ mailing list: http://imagej.nih.gov/ij/list.html