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Don't understand zooming a JPEG in Library

Jun 20, 2012 2:50 PM

I am trying to understand something that has been bothering me for a long time.  It is particularly annoying now that I am eadling with Nikon D800 NEF files.


OS X 10.7.4

Mac Pro 1,1 (5 years old!)

2X, 2.66 GHz XEON processors


128 GD SSD with catalog and application

1 TB Seagate containg all data.


The first thing I did was generate all 1:1 previews.  For the trace shown below I concentrated on a single preview in the Library module and performed multiple sequences of zoom-in and zoom-out.  The time samples are taken every 1/2 second (I have terrible diagnostic tools!).  The 4 cores are plotted top to bottom.


The first time I zoomed to 1:1 only core number 1 was involved.  This took about 6 seconds!  Going back to the "normal" view took very little time.


The second time I zoomed to 1:1 core #1 started the process and was followed by core #2 which finished the job.


The third cycle looks like the second:  Cores 1 and 2 are both involved.


The third cycled involved core 1 and then core 3.


Patterns such as these persist throughout this and other traces I have collected.


So my question:  Why is there never more than one core active at a given time when zooming to a 1:1 view?  Other applications I have seen make use of all cores.



Screen Shot 2012-06-20 at 4.06.18 PM.png

  • Currently Being Moderated
    Jun 20, 2012 2:52 PM   in reply to Bob_Peters

    On my system - Win 7 64-bit - all 4 cores are used when a preview of 1:1 is generated.

    So, if it doesn't on you system, it's probably not Lr's doing.

    Keep in mind that Lr does not discard the 1:1 preview for some time. So when I go back to "normal" view and then (for the same image) again to 1:1 preview, the CPU doesn't show much activity. Stands to reason because the preview is already generated, and just zooming into a generated preview doesn'r require much CPU.

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  • Currently Being Moderated
    Jun 20, 2012 3:13 PM   in reply to Bob_Peters

    If your CPU takes 12 seonds, that means in my opinion that there is a bottleneck somewhere in your system.

    The bottleneck could be

    a) one hardware component that is not "up to speed" so that the CPU sits idle - or uses only one core;

    b) a sub-optimal configuration of your hard drives. In this case your hard drives are busy reading and writing while the CPU is on stand-by.


    See here what Adobe has to say about optimazition of Lr: l


    Regarding configuration of hard drive(s): See my post in the following thread:
    It's post # 9 - but read also # 10.

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  • Currently Being Moderated
    Jun 21, 2012 8:13 AM   in reply to Bob_Peters

    Bob_Peters wrote:



    A request:  Please download a few D800 NEF files from the web, run them through your hardware and report the results.


    Sorry, I won't do that for various reasons:

    a) from where on the web?

    b) I probably would violate someone's copyright;

    c) don't have the time to do that;

    d) the results would be meaningless.


    Please understand that this is a user-to-user forum and as volunteers we have only so much time to dedicate.

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  • Currently Being Moderated
    Jun 21, 2012 8:44 AM   in reply to Bob_Peters


    a) What's dpreview?

    b) But I have. I am not downloading images from somebody else's website, period.

    d)  We two have completely different systems.

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  • Currently Being Moderated
    Jun 21, 2012 8:47 AM   in reply to Bob_Peters

    Bob_Peters wrote:


    A request:  Please download a few D800 NEF files from the web, run them through your hardware and report the results.


    What results do you want, exactly?


    Zooming in and out to see how many cores are being used is, to me at least, a pretty pointless exercise....zooming in and out on a few downloaded D800 nefs is instant, same as it is for all my own Canon 5DII files, so it really doesn't matter whether one core or eight cores is being used as I can't see how it could be quicker. Having said that if I rapidly zoom in and out it looks as though maybe 4 of 8 cores show some activity, though none of them are highly active. So if it truly takes 6 seconds to zoom in/out on your system(s), there's maybe something not right about your setup.


    When loading one of the nefs in Develop it takes approximately 4.5 seconds for the 'loading' indicator to disappear, which is a second or two longer than the 5DII files....but sliders are still activated sub second, which is all I'm interested in as I routinely have the 'loading' indicator turned off.


    Imported them into a new catalog with minimal previews, then rendered 1:1 previews....which took about 6.5 seconds per image. My 5DII files take on average 4 seconds to render 1:1 previews.


    Hope that helps.

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  • Currently Being Moderated
    Jun 21, 2012 9:11 AM   in reply to Bob_Peters

    You are certainly asking a lot of questions and primarily how LR and OSX interact with each other with SMP enabled software.


    One possible answer is the conversion process to a 1:1 preview might be proprietory software addon which is included in LR which is currently not SMP enabled. This type of software addons occur regularly within software houses where they purchase other software to do a job which otherwise might be cost prohibitive because of the labour intensive task of replicating the same process (i.e. re-inventing the wheel).


    OSX itself might be prohibiting LR from running more than one core for that process. i.e. How LR is doing the process might be only limited to one core. Future optimisation will fix this.


    The list of potential reasons could go on if I thought about it.


    A few things to be aware.


    D800 NEFs are nearly 75Mb in size. These are massive files comparably to lower end DSLR cameras with much less megapixels so you might have to forgive some systems being unable to process it quick enough. There is a lot of data and a lot of interpretation going on in the background. Not to mention taking into account anti-virus software and other software interfering in the process.


    I'm not entirely sure whether a 1:1 preview are actually jpegs. It might possibly be in a format which is a lossless format of converted data to represent the image rather than having to interpret the NEF or DNG (if you converted your NEFs to DNGs). Only in the minimal previews does Adobe reference that they are jpegs.


    Sometimes using a SSD isn't enough, you need to have a SATA3 compatible SSD with a SATA3 port to improve data throughput and consistently.


    Also the type of SSD can also be an issue. I'm aware that some SSD drives are just not going to cut it at all. I'm a big fan of Intel SSD and have found them extremely reliable and consistent performers. Scouting forums to verify that your brand and model are found to be reliable and consistent is recommended. Not all SSD drives are alike and the technology is only in its baby stages comparably to the rest of the HDD industry. So buyer beware.


    Most importantly is to provide as much feedback as possible to yet another baby product, Lightroom, comparably to its big brother, Photoshop. Software development can be difficult and to build a product from the ground up needs feedback and whether you can reproduce the same issue(s) reliably. This will help bugs to be ironed out and resolved in the hope of turning out a better, faster, stronger product.


    Even though it doesn't look like it, Adobe developers do pay attention to you airing your grievances and is also the reason why they supply release candidates to the software to the general public. The more testing by as many people result in a greater feedback pool and no matter the amount of testing, someone will always find an issue.

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  • Currently Being Moderated
    Jun 21, 2012 10:00 AM   in reply to wizard155

    Windows 7 64 bit, 2.8GHz i7-860, 12 GB, LR4.1 final


    All eight threads (hyperthreading enabled quad core processor) are used to build and update the previews on this system.


    11 sec. to build the initial D800 NEF preview in the Library module

    0.25 sec. to Zoom 1:1 and build image

    2 sec. to 12 sec. to update 1:1 Library preview after making changes in the Develop module, depending on what is changed.


    Overall LR4.1 final seems about 1.5x to 2x times slower with the D800 NEF than my 5D MK II CR2 files (20Mp), but still acceptable.

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  • Currently Being Moderated
    Jun 21, 2012 6:41 PM   in reply to Bob_Peters

    I'd love to make some suggestions about how to improve your mac but unfortunately there aren't many suggestions which I can make other than the obvious, get a new one The new Intel Core i5 and i7 processors are freakin' fast and I'm looking forward to building my clients beast machine which is going to be running triple NEC 25.5" MultiSyncs, 32Gb of ram, a boatload of storage and SSD boot drive but unfortunately not many people have his budget to spend on his hobby!


    Older hardware can't take advantage of all the new optimisations which are present in the newer versions of the OSX. Plus newer CPUs have smaller cores which translate to less distance to cover to crunch data, more cores, more on die cache, less heat build up and are generally a lot more efficient and quieter.


    If you haven't already, get yourself an Intel SSD which can support the OS and your LR plus cache. Get a newer hard drive to store your photographs onto and of course, make sure you have at least one backup!


    Hard Drives have movable parts in them and they eventually wear out. I've been amazed how much faster a notebook or PC will run if you replace the hdd in them. SSD drives do have a shelf life as well and don't think because they don't "move" that they don't wear out. Intel provides a toolbox software to optimise your SSD drive(s) regularly and to give you a running guide on how well your SSD drive(s) are going. I'm certain other SSD manufacturers have similar tools.


    If you do have an SSD, check whether there are newer firmware updates for it. These firmwares can improve the lifespan of SSDs, better disk optimisations and compatibility. But please please please make sure you have a full backup before attempting a firmware update. If it all goes south, then SSDs are very unforgiving to you and your data in the event of a failure.

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