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Lightroom export will only open 25 images per external process

Jul 26, 2012 1:29 AM

Tags: #export #lr4 #lightroom4 #ptgui


I use the Lightroom 4.1 export feature to export my HDR panorama images as 16 bit tiff in a temporary folder and after that to open the images automatically in PtGui Pro 9.1.x. The problem is if I export more than 25 images PtGui Pro starts one time for the first 25 images, then a second time for image #26 till 51, and so on. This happens during all my test with multiple image formats like 8 bit tiff with/without compression or with jpegs. It makes no difference whether the temporary folder is located on an SSD or a regular hard drive.


Additional I tested LR4 Export to Hugin 2011.4.0 (32Bit) and Gimp 2.8 (64Bit) and the result is the same like with PtGui Pro: After the 25th image a new instance of the program started.


Because of this behavior in different programs, I must assume that the fault must be with Lightroom. Is there any hardcoded limits by handover of pictures to external programs?


Regards, Mike



(Windows 7, Lightroom 4.1 and PtGui Pro 9.1 are 64 Bit versions)

  • Currently Being Moderated
    Jul 26, 2012 3:26 AM   in reply to Mike.Ke



    It might be a Windows limitation. There might be a maximum size to the string of filenames passed to whatever app you're calling. I think that the entire disk address (all the folder names) is passed for each file. How deep in your directory structure is the temporary folder?


    You could try an experiment: write to a temp folder with a one character name at root level. See if you can get more than 25 images passed.



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  • Christophe CUSSAT BLANC
    24 posts
    Aug 29, 2006
    Currently Being Moderated
    Jul 26, 2012 4:03 AM   in reply to Hal P Anderson

    It is a windows limitation. You can only use 2048 characters per command lines on windows (8192 with some versions). One of the solution is to write a script (BAT) that lauch PtGuiPro on a directory at the end of the export or to launch manualy PtGuiPro.

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  • Currently Being Moderated
    Jul 26, 2012 2:23 PM   in reply to Christophe CUSSAT BLANC

    According to Windows XP and all newer versions support 8191 characters per command line. I don't know whether Lightroom still runs on Windows 2000, but I think this is no reason to artificially limit the number of files that can be passed to another program.



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