hugin-devs team mailing list archive

[oleksandr korneta <atenrok@xxxxx>]

this is what I'm getting when trying to generate HDR panorama out of 6
.tiff images (see screenshot).
http://img718.imageshack.us/img718/4981/screenshot2010121313240.png

>From left to right HDR tiff, HDR exr and blended tif. Note the black
stripe on the bottom of hdr images and complete LDR image. I have other
examples where an image comes out with ~1/6 black rectangle in the
upper-right corner, and another HDR image which comes totally black with
a white bar across. Worth noting, that out of set of 6 panoramas I'm
working on right now, 3 HDR files came out as expected, the other three
are corrupt.

$ rpm -q hugin enblend
hugin-2010.4.0-0.1.20101127hg.fc13.x86_64
enblend-4.0-4.fc13.x86_64

Please let me know how else I can help with data on bug.

-- 
You received this bug notification because you are a member of Hugin
Developers, which is subscribed to Hugin.
https://bugs.launchpad.net/bugs/678694

Title:
  EXR files quietly clipped (black rectangles in output)

Status in Hugin - Panorama Tools GUI:
  Confirmed

Bug description:
  The EXR file format has a maximum encoding value of 65504.   The Hugin data flow maintains the absolute exposure through use of the Ev field which effectively scales pixel values.   When using Hugin/Nona on an HDR series that includes very bright elements (such as a very bright sky with a very short exposure), some pixels end up with values above 65504.   When these are written out by Nona, those pixels are written as NaN's in the EXR output file. 

If enblend is then used, the problem is further exacerbated.   A single NaN pixel results in NaN for entire rectangle of enblend's pyramids.   The end result are large black rectangles in the output file.

If output is changed to TIFF, then everything works fine.

Nona should warn when clipping occurs and then output the maximum possible value rather than a NaN.   I assume this is the OpenEXR library itself and probably affects other applications.   In fact, if a TIFF generated as above is opened in PhotoShop, it looks fine, but if it is resaved as EXR, the same NaN pixels are created.