| Author | Message | ||
     Dennis Lee New member Username: Dennislee Post Number: 1 Registered: 03-2006 |
I was disappointed to see that the RAW convertion in PWP 4.0 beta uses AHD interpolation. The primary problem I see with AHD is its signature mosaic pattern of low amplitude color errors. This pattern looks like a mesh of horizontal and vertical lines one pixel wide and a few pixels long, and is most visible in dimly lit areas and in the presence of noise. In one image I thought the black level was not set correctly. However, upon closer inspection it was obvious that what I was seeing was this pattern of color errors. Of course, in areas of near black, the only visible information is this pattern. I've also noticed that sharpening tends to enhance this pattern. AHD also has problems with aliasing artifacts (aka 'maze') and false colors near the sampling limit (ie fine image details that are about one pixel apart). In one image I have converted, AHD rendered the lattice-work inside a distant window as high contrast geometric patterns that have no basis in reality (in other words, it looked really wierd!). PWP is a great product and needs a professional quality demosaicing algorithm if it is to support RAW convertion. Are there plans to improve this algorithm before 4.0 is released? Thanks, Dennis | ||
| Kiril Sinkel Member Username: Ksinkel Post Number: 181 Registered: 08-2002 |
Dennis, AHD is considered state of the art by many. That said, there is probably no single method that is best for all images. We can make VNG available for cases where it's preferable. Beyond that, we are looking at other methods for the longer term, but that will be beyond the 4.0 release. Kiril | ||
| Elie Dinur Member Username: Elied Post Number: 111 Registered: 07-2003 |
I would very much like to have a VNG option. Elie | ||
| Dennis Lee New member Username: Dennislee Post Number: 2 Registered: 03-2006 |
Kiril, Thank you for the reply. I know interpolating the bayer pattern is a very difficult task to do well. AHD and VNG are convenient to implement because source code for them is available in dcraw. However, compared to the leading RAW converters they produce significant visible artifacts, even if they are considered "state of the art". This is apparently one of the cases where academia hasn't caught up with the proprietary algorithms in commercial products. Because PWP is an outstanding product it deserves RAW convertion that is competetive with other products on the market. Hopefully Digital Light & Color has the resources and inclination to develop or acquire a demosaicing algorithm that measures up to the rest of PWP's image processing. Thanks again, Dennis | ||
| Dieter Mayr Member Username: Dieter_mayr Post Number: 269 Registered: 11-2004 |
Seems to be a good thing to have the possibilty to change between AHD and VNG, since there seems to be reasonable differences, to what i have seen till now. Dieter | ||
| Kiril Sinkel Member Username: Ksinkel Post Number: 188 Registered: 08-2002 |
I can add a VNG/AHD option to the next beta drop. Kiril | ||
| Andreas Siegert Member Username: Afx Post Number: 7 Registered: 03-2006 |
Hmmmm, maybe I am totally off, but talk to Eric Hyman at Bibblelabs. His RAW conversion engine is pretty good, fast and he does make deals occasionally. If I could get Bibble RAW conversion and PWP editing in one package I'd be closer to the perfect solution ;-) cheers afx cheers afx | ||
| Lorenzo Unregistered guest |
Gentlemen, for my Canon 20D I have used so far Raw Shooter Pro and Adobe Camera Raw for raw conversion (forget the Canon DPP: I had to re-convert and re-postprocess a bunch of images). I have no idea what interpolation they use but comparing Tiffs out of the three, post processed with same workflow in PWP I find: none of the artifacts mentioned, maybe I don't have images with difficult patterns. RSP and ACR, even with all options for noise reduction to zero, produce images quite cleaner (less noise) at the expense of fine details. Both RSP and ACR give, straight inside the raw converter, more control than PWP4 on exposure, white balance, saturation, brightness, use of dynamic range etc., but: they need anyhow a further processing with PWP, at least because neither does sharpening well, best to keep USM for PWP, the converted output of PWP4 "as is" contains all informations, is very usable and combined with a good workflow including a final robust sharpening makes A3 prints that I judge better than the ones from ... "competition". If I really want to do some for noise the combination of PWP4 and a dedicated tool as Neatimage gives the best results. Ciao Lorenzo |
