[Elphel-support] Questions about JP4

[Florent Thiery]

Hi,

>
>>    - (how) can i render a JP4 image to RGB using ImageJ plugins ? I can
>>    successfully import it (but it is still gray with squares)
>>
>> Converting from Bayer mosaic is not a trivial task, there is no single
> "best" conversion - there are many different de-mosaic or de-bayer
> algorithms, each with different features. Some may work better for nature
> photos, some - for photos with multiple straight and parallel lines (such
> as text, or photos of man-made structures, like buildings or fences). I was
> able to find some ImageJ de-bayer algorithms, but they were rather basic.
>

Okay, no worries.


>>    - is there a C implementation somewhere similar to our JP46 to bayer
>>    code<http://code.google.com/p/gst-plugins-elphel/source/browse/trunk/jp462bayer/src/gstjp462bayer.c#856> so
>>    that we can port it ? If not, where can we have more information regarding
>>    the difference between JP46 and JP4, and the according decoding adjustments
>>    needed ?
>>
>> Yes, there is a C implementation of the JP4 conversion, but I would
> recommend you to keep an eye on the java implementation in ImageJ plugin.
>

Alright, so to sum up the ImageJ JP4/JP46 importer plugin does the JP4* to
Bayer conversion. We will take a look. The reason we need a C
implementation is for inclusion into a gstreamer plugin.


> Once in a while we add more parameters that are passed from the camera via
> Exif MakerNote  field, and the ImageJ implementation is always maintained
> to match the latest camera firmware.
>

Does the JP4 to Bayer step require to parse the parameters (which AFAIK is
not the case with JP46) ?


> You may find C-code here: http://wiki.elphel.com/index.php?title=Movie2dng(or just search for movie2dng ) , but it may be a little behind the latest
> MakerNote.
>

Thanks

Florent
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