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-   -   More RAW musings and question on ACR vs. DPP (http://www.velocityreviews.com/forums/t429876-more-raw-musings-and-question-on-acr-vs-dpp.html)

W 10-17-2006 03:41 PM

More RAW musings and question on ACR vs. DPP
 
Folks,

Focusing on one problem area I see with ACR vs. DPP (used with 20D).
That is, noisy and or posterized shadows. I have noticed that ACR seems
to push a reltatively significant amount of the blue channel down to
'0' vs. DPP. I had an image, when converted with DPP showed reasonable
histograms in R, G, and B, nicely tailing off at the low end with no
spikes at '0'. The same image when convereted with ACR (even with
exposure adjusted up, shadows set to '0', etc....i.e. the image looked
brighter than the DPP conversion) seemed to always have a spike of blue
values at '0' in the histogram(both set to Adobe1998 space). I wonder
if this is why I tend to get noisy shadows with ACR compared to DPP?
I also played with white balance and the problem remained. Has anyone
else experienced this issue?

W


bmoag 10-17-2006 09:33 PM

Re: More RAW musings and question on ACR vs. DPP
 
You really should try a few other converters to realize that the programmers
have made arbitrary decisions about baseline settings when images are first
opened.
You should, however, be able to get images to the same point regardless of
the converter using both the converter and Photoshop.
Photographers have preferences for different converters because their
aesthetic preferences correspond to those that guide the programming of the
converter they prefer or the workflow that the converter follows.
Having tried nearly every Nikon compatible converter I can only see this as
an aesthetic and not a technical issue.



W 10-17-2006 11:10 PM

Re: More RAW musings and question on ACR vs. DPP
 
I understand your point and it generally makes sense. However, when I
find the reality of 'standing on my head' in an unsuccessrful attempt
to make ACR not clip the low end of the blue channel (leaving a spike
at 0) while DPP does this at its default starting point with this image
I begin to wonder. I also see the attendant noisy shadows which I
suspect is related to this. I have to wonder if in the 'gamma
conversion' stage (or who nows where), ACR just doesn't (at least for
the 20D) 'do it right' and the user is left to unsuccessfully try to
correct its 'mistakes'.
All I really want to do is shoot photos. I thought I was happily
settled on ACR, but these issues are convincing me otherwise. I don't
know the details of the basic RAW conversion stage, but I have to
wonder if ACR is making some 'wrong assumption' about the blue pixels
in the Bayer array or gamma correction or who knows what. I don't know
how much these things differ between sensors, but I would think Canon
knows the details of their sensor better than any third party. I am not
a fan of DPP user interface, I love CA correction in ACR (lens
correction in PS proper does not seem to do as good a job). BUT, if DPP
gives 'better looking' results overall (cleaner shadows, better overall
rendition), I will have to go there.

W


bmoag wrote:
> You really should try a few other converters to realize that the programmers
> have made arbitrary decisions about baseline settings when images are first
> opened.
> You should, however, be able to get images to the same point regardless of
> the converter using both the converter and Photoshop.
> Photographers have preferences for different converters because their
> aesthetic preferences correspond to those that guide the programming of the
> converter they prefer or the workflow that the converter follows.
> Having tried nearly every Nikon compatible converter I can only see this as
> an aesthetic and not a technical issue.




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