Question about "create Selection"

[Winfried Wurm]

Hello,

I have a binary Image of small white objects and want to measure the area of them. When I run "Create Selection" it sometimes selects the white Objects and sometimes the black area around them (in the same picture).
So far I could not figure out when wich of both things happens.
Can someone explain me when "Create Selection" selects the white and when the black area of an Image?


Thanks in advance
Winfried Wurm
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[6:1135]

hi,
I am surprised that this is random
usually it depends on the ImageJ parameter : edit / options / colors ...
foreground and background define what will be considered as background or object by the automatic tool selection ...

[Michael Schmid]

Hi Winfried,

it should depend on the state of the 'Black Background' checkbox in  
Process>Binary>Options, whether white or black is considered background.

If you have always the same pixel value for your foreground objects,  
you can also set the threshold (to a range that encompasses the  
foreground objects, i.e., makes them red) and then run "Create  
Selection".

Michael
________________________________________________________________

On 24 Nov 2011, at 15:06, Winfried Wurm wrote:

> Hello,
>
> I have a binary Image of small white objects and want to measure  
> the area of them. When I run "Create Selection" it sometimes  
> selects the white Objects and sometimes the black area around them  
> (in the same picture).
> So far I could not figure out when wich of both things happens.
> Can someone explain me when "Create Selection" selects the white  
> and when the black area of an Image?
>
>
> Thanks in advance
> Winfried Wurm

[Michael Schmid]

Hi Gilles,

Edit>Options>Colors has nothing to do with the interpretation of  
colors in binary (mask) images.
Edit>Options>Colors sets the foreground color that you get with the  
'Fill' command and the pencil and brush tools in the standard toolset  
(from the standard StartupMacros.txt). Its background color  
determines what color the 'Clear' command and eraser tool use.

As I wrote earlier, interpretation of colors in binary images or  
masks depends on the 'Black Background' checkbox in  
Process>Binary>Options.

Michael
________________________________________________________________

On 24 Nov 2011, at 16:08, Gilles Courtand wrote:

> hi,
> I am surprised that this is random
> usually it depends on the ImageJ parameter : edit / options /  
> colors ...
> foreground and background define what will be considered as  
> background or
> object by the automatic tool selection ...

[6:1135]

uh, you're right i apologize

[Winfried Wurm]

Thanks for the answers.
Changing the Option in Binary didn´t seems to make a diffrence, but setting the Thresholds again to (255,255) worked fine.

>-----Ursprüngliche Nachricht-----
>Von: "Rasband, Wayne (NIH/NIMH) [E]" <[hidden email]>
>Gesendet: 24.11.2011 16:50:44
>An: "Winfried Wurm" <[hidden email]>
>Betreff: Re: Question about "create Selection"
>
>>On Nov 24, 2011, at 9:06 AM, Winfried Wurm wrote:
>>
>>> Hello,
>>>
>>> I have a binary Image of small white objects and want to measure the area of them. When I run "Create Selection" it sometimes selects the white Objects and sometimes the black area around them (in the same picture).
>>> So far I could not figure out when wich of both things happens.
>>> Can someone explain me when "Create Selection" selects the white and when the black area of an Image?
>>
>>"Create Selection" will always select white objects if you you first select them using the Image>Adjust>Threshold tool or using the setThreshold(255,255) macro function.
>>
>>Best regards,
>>
>>-wayne
>>
>

... [show rest of quote]

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