Re: [CinePaint] Cant get Bracketing to HDR working

Am Montag, 18. Dezember 2006 13:51 schrieb Stefan Podkowinski:

> Hello
>
> I recently build cinepaint v.0.21 from gentoo portage tree in order
> to create HDR images from a set of jpegs. Unfortunately, after
> selecting three images and confirming "compute response" or "HDR",
> I just get the following error. Am I missing something or is this a
> bug?

Hello Stefan,

the method (QR decomposition) used here for solving a last square fit 
fails if the matrix has a rank defect. So far I didn't come across 
with such case with usual images, I implemented firstly only this 
method, because it is fast. There exists an alternative method 
(singular value decomposition - SVD), which works also for defect 
matrices, but is 5-10 times slower. Since plugin version 0.5.1 
(CinePaint v0.21-2) both methods have been inserted, as default 
behavior QR is tried at first and if it fails, SVD is used. This can 
be changed under "Settings" -> "Method for solving the last square 
fit". But I am afraid, the result will nethertheless not be very 
good, because the  algorithm used here for recovering the camera 
response function is not very stable for noisy data. At 

  http://sourceforge.net/projects/pfstools/

you can download a set of command line tools for HDR creation, wherein
a more stable algorithm is realized (takes some more time). It would 
be probably a good idea to adapt that for the plugin.

Btw: Shortly I will put in the CVS a new version, which can read
EXIF data and can correct small displacements (offsets)
between images. The current state is a bit burdensome in respect
of this.

Greetings,
Hartmut

-------------------------------------------------------------------------
Take Surveys. Earn Cash. Influence the Future of IT
Join SourceForge.net's Techsay panel and you'll get the chance to share your
opinions on IT & business topics through brief surveys - and earn cash
http://www.techsay.com/default.php?page=join.php&p=sourceforge&CID=DEVDEV