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From: Sylvia on 30 Mar 2010 08:11
Hi,

I want to use imshow command imshow(I,[low high]) for displaying different
images. All images have different minimum and maximum intensity values. I
want to show all images on the same scale i.e between same range of maximum
and minimum intensities.
say image1 has minimum intensity values of 0.5 and maximum 0.2
image2 has minimum intensity values 0.8 and maximum 0.3.
I want to display these images in the same range of [-1 1]

The command
imshow(Image,[-1 1]) wont work

The standard imshow command can do compressing the range of intensities but
how to expand the range?

From: Tim Wescott on 30 Mar 2010 11:05
Sylvia wrote:
> Hi,
>
> I want to use imshow command imshow(I,[low high]) for displaying different
> images. All images have different minimum and maximum intensity values. I
> want to show all images on the same scale i.e between same range of maximum
> and minimum intensities.
> say image1 has minimum intensity values of 0.5 and maximum 0.2
> image2 has minimum intensity values 0.8 and maximum 0.3.
> I want to display these images in the same range of [-1 1]
>
> The command
> imshow(Image,[-1 1]) wont work
>
> The standard imshow command can do compressing the range of intensities but
> how to expand the range?
>
Images are generally encoded as sets of non-negative numbers. Are you
sure you don't want to use the range [0, 1]?

--
Tim Wescott
Control system and signal processing consulting
www.wescottdesign.com
From: Sylvia on 30 Mar 2010 11:14
As those are the images phase, would be best to have range in negative and
positive but expanding the display range from [0.2 0.5] to [0 1] would also
give some help.
>Sylvia wrote:
>> Hi,
>>
>> I want to use imshow command imshow(I,[low high]) for displaying
different
>> images. All images have different minimum and maximum intensity values.
I
>> want to show all images on the same scale i.e between same range of
maximum
>> and minimum intensities.
>> say image1 has minimum intensity values of 0.5 and maximum 0.2
>> image2 has minimum intensity values 0.8 and maximum 0.3.
>> I want to display these images in the same range of [-1 1]
>>
>> The command
>> imshow(Image,[-1 1]) wont work
>>
>> The standard imshow command can do compressing the range of intensities
but
>> how to expand the range?
>>
>Images are generally encoded as sets of non-negative numbers. Are you
>sure you don't want to use the range [0, 1]?
>
>--
>Tim Wescott
>Control system and signal processing consulting
>www.wescottdesign.com
>
From: Tim Wescott on 30 Mar 2010 11:28
Sylvia wrote:
(top posting fixed)
>> Sylvia wrote:
>>> Hi,
>>>
>>> I want to use imshow command imshow(I,[low high]) for displaying
> different
>>> images. All images have different minimum and maximum intensity values.
> I
>>> want to show all images on the same scale i.e between same range of
> maximum
>>> and minimum intensities.
>>> say image1 has minimum intensity values of 0.5 and maximum 0.2
>>> image2 has minimum intensity values 0.8 and maximum 0.3.
>>> I want to display these images in the same range of [-1 1]
>>>
>>> The command
>>> imshow(Image,[-1 1]) wont work
>>>
>>> The standard imshow command can do compressing the range of intensities
> but
>>> how to expand the range?
>>>
>> Images are generally encoded as sets of non-negative numbers. Are you
>> sure you don't want to use the range [0, 1]?
>
> As those are the images phase, would be best to have range in
negative and
> positive but expanding the display range from [0.2 0.5] to [0 1]
would also
> give some help.

So first you have the task of converting a non-image to an acceptable
range for an image: Image = ImagePhase + 1

Then you can show it:

imshow(ImagePhase + 1, [0, 2])

Not, mind you, that I'm sure that the negative argument in imshow was
your problem in the first place -- that was just an educated guess.

--
Tim Wescott
Control system and signal processing consulting
www.wescottdesign.com
From: Sylvia on 30 Mar 2010 11:44
As those are the images phase, would be best to have range in negative and
positive but expanding the display range from [0.2 0.5] to [0 1] would also
give some help.
>Sylvia wrote:
>> Hi,
>>
>> I want to use imshow command imshow(I,[low high]) for displaying
different
>> images. All images have different minimum and maximum intensity values.
I
>> want to show all images on the same scale i.e between same range of
maximum
>> and minimum intensities.
>> say image1 has minimum intensity values of 0.5 and maximum 0.2
>> image2 has minimum intensity values 0.8 and maximum 0.3.
>> I want to display these images in the same range of [-1 1]
>>
>> The command
>> imshow(Image,[-1 1]) wont work
>>
>> The standard imshow command can do compressing the range of intensities
but
>> how to expand the range?
>>
>Images are generally encoded as sets of non-negative numbers. Are you
>sure you don't want to use the range [0, 1]?
>
>--
>Tim Wescott
>Control system and signal processing consulting
>www.wescottdesign.com
>
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