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From: Mike on 4 May 2010 02:14
Hi
Just an impixel question:

>> a=rand([256 256 3]);
>> a(1,1,:)=255.;
>> figure;
>> imshow(a)
>> impixel % here I click pixels at (1,1), (1,2) , (2,2) and (2,1)

ans =

1.000000000000000 1.000000000000000 1.000000000000000
0.935956007375390 0.762701082555705 0.297926592746646
0.687563039047706 0.394728451046901 0.123781049683410
0.782910876575916 0.976887314178435 0.844799166919494

why are the first point's values all one?

Mike
From: Walter Roberson on 4 May 2010 02:35
Mike wrote:
> Hi
> Just an impixel question:
>
>>> a=rand([256 256 3]);
>>> a(1,1,:)=255.;
>>> figure;
>>> imshow(a)
>>> impixel % here I click pixels at (1,1), (1,2) , (2,2) and (2,1)
>
> ans =
>
> 1.000000000000000 1.000000000000000 1.000000000000000
> 0.935956007375390 0.762701082555705 0.297926592746646
> 0.687563039047706 0.394728451046901 0.123781049683410
> 0.782910876575916 0.976887314178435 0.844799166919494
>
> why are the first point's values all one?

Data value 255. is out of the range permitted for true-color images that
are stored in double precision, which are required to be in the range 0
to 1. Rather than refusing to show the image, imshow clamped the value
at the maximum allowed.
From: Mike on 4 May 2010 06:08
On May 4, 2:35 pm, Walter Roberson <rober...(a)hushmail.com> wrote:
> Mike wrote:
> > Hi
> > Just an impixel question:
>
> >>> a=rand([256 256 3]);
> >>> a(1,1,:)=255.;
> >>> figure;
> >>> imshow(a)
> >>> impixel   % here I click pixels at  (1,1), (1,2) , (2,2) and (2,1)
>
> > ans =
>
> >    1.000000000000000   1.000000000000000   1.000000000000000
> >    0.935956007375390   0.762701082555705   0.297926592746646
> >    0.687563039047706   0.394728451046901   0.123781049683410
> >    0.782910876575916   0.976887314178435   0.844799166919494
>
> > why are the first point's values all one?
>
> Data value 255. is out of the range permitted for true-color images that
> are stored in double precision, which are required to be in the range 0
> to 1. Rather than refusing to show the image, imshow clamped the value
> at the maximum allowed.- Hide quoted text -
>
> - Show quoted text -

thank you.

Mike
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