Questions
1. Has anyone seen this?
2. Is it some kind of out-of-gamut warning?
3. Any other ideas?
Yellow highlights get red posterization
I saw this in a german forum a few weeks ago. The file was a canon cr2, but same behavior.
This guy had the problem on one pc, on another pc it was ok.
As I remember, it was a problem with video card or driver.
I downloaded your raw file and have no problems in lightroom.
Juergen
Yellow highlights get red posterization
Try to change your monitor profile to see if it helps.
Ondrej Pokluda:
I downloaded the original file and imported it into Lightroom (Macintosh version). I do not see a problem anywhere. The *very slight* blown channel is corrected by adjusting the Recovery slider to 11. No exposure adjustment was necessary.
Ondrej,
This was observed and discusset in at least two threads in this forum. Search
for the ''Buggy preview'' thread here. It was also discussed, extensively, in the
Flickr Lightroom group. I had an Athlon XP 1700 and had this problem. I now
have a Core2Duo 6300 and no more problem. Let me quote from an earlier post:
''It seems that Alexander Kiel, a member of the Flicker LR Group, has found out
what appears to be causing the problem: older processors (before Intel P4 and
Athlon 64) don't use the SSE2 instruction set. Somehow, the arithmetic of LR's
rendering engine produces ''buggy previews'' when executed on earlier processors
with the older SSE instruction set. (Precision of floating point arithmetic with
32 bits versus 64 bits).''
LR requires the SSE2 instruction set in/for the processor, as I understand it.
Would be very interested in knowing which OS/processor you use?
Chris
By the way, this problem does not only affect the previews, if affects your
exported files as well.
Thanks to everyone, especially to Chris. Yes you are right, I run Lightroom on Athlon XP 1700 running Windows XP Pro CZ. I will try to test in on another computer.
''It seems that Alexander Kiel, a member of the Flicker LR Group, has found out
what appears to be causing the problem: older processors (before Intel P4 and
Athlon 64) don't use the SSE2 instruction set. Somehow, the arithmetic of LR's
rendering engine produces ''buggy previews'' when executed on earlier processors
with the older SSE instruction set. (Precision of floating point arithmetic with
32 bits versus 64 bits).''
Chris, the above is not true. I imported Ondrej's original photo into Lightroom in an Intel Celeron CPU 2.00GHz SiS 650 Display Adapter with only 32MB Graphics and i did not see any problem.
Espart,
you are right, newer Celerons, starting with the Celeron 1.7 (Willamette 128)
and Mobile Celeron 1.7 (Northwood 256) use the SSE2 instruction set - thus you
see no problem, and the hypothesis still stands.
(Reference: http://en.wikipedia.org/wiki/List_of_Intel_Celeron_microprocessors)
Chris
As I have just found a processed image that has this posterized affect , I tried searching for '' Buggy Preview '' as suggested by Chris Diewald but with no luck at all .
Could you Chris give a few more details so that I can find the right threads ?
Also , I don`t suppose it`s possible to install the SSE2 set into my old Athlon setup , is it ? I have no real prospect of a newer computer any time soon .
Thanks in advance for any help .
When searching, you need to go to the home LR forum page and click on the search there. If you search from this thread, the search engine only searches this topic.
- Pierre
John,
the URL of the thread you are looking for is
http://www.adobeforums.com/cgi-bin/webx?14@@.3bc360c1/0
(''Buggy preview'')
In the Flickr Lightroom Group, the URL is:
http://www.flickr.com/groups/adobe_lightroom/discuss/72157594566275084/
(''Nasty highlight problems'').
In the absence of a revised version of LR, it appears there is little you can do
with the older processors, because you cannot upgrade their ''Instruction set''
to SSE2. I even doubt that a new version can do much about that. The problem
appears to be related to the precision of ''floating point'' (non-integer)
calaculations that LR does; that precision is higher with SSE2. I didn't upgrade
my processor to Core 2 Duo for that reason, but I was lucky to get rid of the
problem as a side benefit, apart from a phantastic speed increase...
Chris
I am having this issue too. Is this the official account of this problem? It's hard to believe that color rendering (and only yellow...?) would be so affected by floating point calculations. But then I'm no computer scientist either...
But I do hope there's a software fix in the future for this.
No, it's nothing official. It is a hypothesis developed by someone in the
Flickr group on LR, that seems to be consistent with the relationship with the
processor used and occurrence of the problem. Whether software can solve this,
I really don't know. But note that Adobe contacted the guy in the Flickr group
who first posted about the yellow highlights problem...
That is a good sign that he was contacted by Adobe. But then he's apparently had no further communication with them. Granted, my home-built PC is getting up there in age, but my Athlon 3200 hasn't missed SSE2 to date. I hate the thought of a whole new build just to get yellow to render correctly. That's a hard pill to swallow.
Great stuff , Chris D , many thanks for your help ; I was pretty sure that the SSE2 set wasn`t backwards installable , but it`s helpful to know for certain .
Amazingly , I looked for ''Buggy Preview '' but was told it didn`t exist ; someone on another thread said that ''Search'' was rubbish , and this seems to prove it .
%26gt;Amazingly , I looked for ''Buggy Preview '' but was told it didn`t exist ; someone on another thread said that ''Search'' was rubbish , and this seems to prove it .
This is rubbish because someone posted that thread for you. and search works. You just have to know when and where and how to use it.
I just searched for
Buggy Preview and found it and a bunch of other post. No problem..
Don
Don Ricklin, MacBook 1.83Ghz Duo 2 Core running 10.4.9 %26amp; Win XP, Pentax *ist D
http://donricklin.blogspot.com/
Don , I can assure you that I entered ''Buggy Preview '' in the search box three times , just as Chris suggested , and was told that no such entry existed each time .
I`m not sure what you mean by ''..someone posted that thread for you...'' , but I thought that you just entered the words you were looking for in the Search box , and then pressed the button ; how do you do it and get your superior results ?
Be sure you are not in this or anyother thread. Only in the long forum thread list. This has been noted many times in many threads.
%26gt;I`m not sure what you mean by ''..someone posted that thread for you...'' ,
%26gt;%26gt;Chris Diewald - 5:55pm Apr 16, 07 PST (#11 of 17)
John,
the URL of the thread you are looking for is
Philipp123, ''Buggy Preview'' #1, 11 Mar 2007 10:58 am
That is the Buggy Preview thread!
Don
Don Ricklin, MacBook 1.83Ghz Duo 2 Core running 10.4.9 %26amp; Win XP, Pentax *ist D
http://donricklin.blogspot.com/
Here is an update:
I installed Lightroom on Core 2 Duo 6400 and problem disappeared, as expected. I searced Czech speaking forums, since Athlon XP had been extremely popular here, and I found relatively many similar reports, without an answer. Posting link to this forum saved one desperate guy from complete system reinstallation. So really *BIG* thanks to Chris Diewald.
Now once we know why we have this problem, is there any chance for solution? I know I run it out-of-spec (although specs were poorly written, under normal circumstances I have a better processor then Pentium 4. I they had written SSE2 required, I would have never bought it). Do Adobe people read this forum? Should I submit an official bug report? I think it is at least worth trying to do something, what would you suggest. (Appart from computer upgrade.)
Ondrej,
I am glad that I was of help, althgough the credit should go to Alexander Kiel
of the LR Flickr group who diagnosed the problem first.
I am almost certain that Adobe is well aware of the problem, but have no idea
whether it can be fixed so as to make LR backward-compatible with the SSE
instruction set.
Chris
Sorry , Don , I wasn`t trying to rile you , it`s just that I` ve only come to this forum in the last month or so , and the need to specify the long forum list is something that must have have been done to death earlier ,
It seems like I or someone posts to that effect virually every time someone is told to do a search. At least daily or nearly so.
I also had this problem when I tried the trial on my AthlonXP PC and i refuse to upgrade my PC just to use LR. Now I use RawShooter instead which works brilliantly. Which also proofs that there's no 64bit floating point precision needed to render yellows without bugs. LR is based on RawShooter, so it got buggered due to sloppy programming when they merged existing, working RawShooter code with their own buggered code.
I'd love to use LR, but it's no necessity as also the sharpening in RawShooter is much better.
Stefan, you've got it wrong, but I am glad you find RS brilliant.
LR's RAW converter is based on ACR- is ACR- and it ain't buggered.
No comments:
Post a Comment