Re: HDR

Posted by Michael Schmid on Apr 30, 2008; 9:26am
URL: http://imagej.273.s1.nabble.com/HDR-tp3696379p3696384.html

Hi Andreas,

there is a bit about HDR in the english Wikipedia, with a few
links
   http://en.wikipedia.org/wiki/High_dynamic_range_imaging

Since almost everyone uses digital sensors now, I think a
first step could be rather simple, get the correlation between
non-saturated pixels values of two input images, and finding
the pixel value offset and factor between the images. Then one
could combine them, maybe with some "smooth transition", i.e.
a weighted sum for pixel values that are reasonably well
exposed on both images.

ImageJ supports float images, so we need not care about special
HDR formats unless we want to read HRD images already present
in such formats.

For the beginning, I think that we don't need all the procedures
to map the high dynamic of a HDR image onto a smaller range for
display - this looks like a the more difficult task.

Best wishes,

Michael
________________________________________________________________
Michael Schmid                    email: [hidden email]
Institut fuer Allgemeine Physik, Technische Universitaet Wien
Wiedner Hauptstr. 8-10/134, A 1040 Wien, Austria
Tel. [phone] or -13453, Fax [phone]
________________________________________________________________

On 30 Apr 2008, at 09:17, Andreas Jahnen wrote:

> Hello,
>
> I will have a look at this in more detail as I would like to have HDR
> functionallity in ImageJ as well.
>
> So far I have used HDR only as a user (pfstools, qtpfsgui) and I  
> need to
> dig into this in more detail. Currently, I think it is not that  
> easy. You
> need to at least support the file formats and have hdr functions
> available. Can anybody recommend good documentation on HDR?
>
> I will keep you informed about my work... .
>
> So long,
>                 Andreas
>
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>
> ImageJ Interest Group <[hidden email]> wrote on 29.04.2008  
> 16:47:37:
>
>> I assume you're looking for HDR photos in the manner of Debevec?  I'm
>> sure it would be fairly easy to implement this in ImageJ, but I
>> haven't seen it done so far.  I've tried that method in Cinepaint  
>> with
>> good results, though just on test images and not technical examples.
>>
>> In ImageJ, we've used a manual approach to combine gel scans that
>> start out sub-16bit.  The end results are worth it, but the method is
>> very time-intensive and I would be very interested in an automated
>> routine.
>>
>> Jonathan
>>
>>
>>
>> On Tue, Apr 29, 2008 at 1:29 AM, Przemko <[hidden email]>
> wrote:
>>> Sylvain Lacomble wrote:
>>>
>>>> Dear all,
>>>>
>>>> Has anyone tried to process HDR images with imageJ?
>>>> This would be extremely useful!
>>>> With my best wishes,
>>>> Sylvain
>>>>
>>>>
>>>>
>>>>
>>>  I would be very interested in HDR on ImageJ as well. I tried it on
>>> Photoshop and one can get very nice Nomarski/Fluorescence overlays.
> Under
>>> normal conditions, Nomarski pictures are rather difficult to take  
>>> but
> HDR
>>> makes it really simpler and much more realistic (WYSIWYG).
>>>  Przemko
>>>
>>>  --
>>>  Przemko Tylzanowski Ph.D.
>>>  LSD & Joints
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>>>  University of Leuven
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>>>  3000 Leuven, Belgium
>>>
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>>>
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