[scikit-image] Image intensity measure.regionprops

[Jeremy Chacon]

Hi Cedric,

I'm just a user but my interpretation is that mean_intensity is the mean
intensity of the pixels in that labeled region, whereas intensity_image is
the region within its bounding box.  So intensity_image can contain zeros
where the label isn't present.

See this:

from skimage import measure
import numpy as np
a = np.array([[2,3,4,5],[6,5,4,3]])
b = np.array([[0,1,1,0],[0,1,0,0]])

rp = measure.regionprops(b, a)

rp[0].mean_intensity  # 4
rp[0].intensity_image  # contains a zero, making the mean of this < 4



On Fri, Jul 14, 2017 at 12:23 AM, Cedric Espenel <cedric.espenel at gmail.com>
wrote:

> Hi scikit-image users/devs,
>
> I'm using skimage.measure.regionprops and I'm little bit confused about a
> result I get with it.
>
> I'm working with a zstack of a microscopy image that I have
> segmented/label and I'm trying to get the mean intensity of the labeled
> region:
>
> region_props = measure.regionprops(label_image, intensity_image)
>>
>
> If now I do:
>
> for prop in region_prop:
>
> print('x', prop.mean_intensity)
>>>
>> print('y', np.mean(prop.intensity_image))
>>>
>>
> prop.mean_intensity and np.mean(prop.intensity_image) give me different
> value, which confuse me. Can someone help me understand why I'm getting
> something different?
>
> Thank you in advance for your help.
>
> Sincerely,
>
> Cedric
>
>
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>


-- 

*___________________________________________________________________________Jeremy
M. Chacon, Ph.D.*

*Post-Doctoral Associate, Harcombe Lab*
*University of Minnesota*
*Ecology, Evolution and Behavior*
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