14 Replies Latest reply: Nov 9, 2011 10:16 AM by léonie
stormlvr Level 1 Level 1 (0 points)

If exporting images for backup, to reimport into a clean aperture or other program, is it better to use 72 dpi or 300 dpi, or does it matter?  I want the best quality for any future unforeseen use. 

  • léonie Level 9 Level 9 (72,215 points)

    Important for the quality of your exported images are the dimensions of your exported images measured in pixels.

    The maximum amount of pixels will be preserved if you pick an export presets with "original size" in its name.

     

    72 dpi or 300 dpi specify the resolution of the image in dots per inch, to be used when the image will by printed or displayed. From these settings the dimensions on the screen or the paper will be computed, its width and height in inches. These settings do not change the amount of storage required, only the geometric interpretion of the pixels.

     

    If your image has 720x720 pixels, and you export it with 72dpi, then the image will be displayed with a size of 10x10 inches.  The same image exported with a resolution of 300 dpi will be printed as a tiny square of 2,4x2,4 inches.

  • Terence Devlin Level 10 Level 10 (133,145 points)

    What is a "clean aperture"? I'm not sure what you're hoping to achieve. Also if you are exporting to re-import you really, really want to be exporting your Masters.

     

    Regards

     

     

    TD

  • stormlvr Level 1 Level 1 (0 points)

    Thanks leonieDF and Terence, for your replies.  By "clean Aperture" I mean a fresh install of Aperture.  I'm having problems with my computer and will be getting the hard drive replaced.  I am in the process of backing things up.  Besides the usual system-wide backups, I want to have a copy of all of my images--both masters and versions--that I can reload into Aperture or another program down the road, if I ever decide to do that.  (I wasn't smart enough to backup the masters BEFORE importing into Aperture, which I plan to do from now on, if I can figure out HOW!)  I just didn't want to lose any image quality in exporting them.  I think you answered my question Leonie, but I'm really stupid in regards to understanding the pixel stuff!!  It's been my understanding that printing at 300 dpi is better, but from what you said, it seems 72 dpi is better for some images??  Can you or someone else explain this to me in VERY simple terms, so I can wrap my head around it?!  All of your help is very much appreciated!!!

  • Frank Caggiano Level 7 Level 7 (25,715 points)

    You really really really should think  about what you are doing here. This is the (very) wrong way to go about backing up an Aperture library.

  • Network 23 Level 6 Level 6 (11,870 points)

    If you want all your masters, just get them out of the Aperture library. Right-click it, Show Package Contents, and your masters are in there. The problem with trying to use the Export command on your "masters" is that there is always a risk you will alter your "masters" with an errant setting, and then they won't be like masters anymore. The package folder contains the originals as true originals.

  • léonie Level 9 Level 9 (72,215 points)

    o.k. I will give it a try.

     

    First of all, Terence Devlin is right - the master files are what you imported into Aperture, and if you want to export without loss of quality, you cannot do better than to export the masters.

     

    I seem to have explained myself poorly:

     

    All about pixels:

     

    A digital image is represented by a grid of picture elements, short pixels:

    The more pixels an image has, the more details you can see in the image.

     

    An image with only a poor resolution: 17 x 13 pixels

    RasterPalmeGrob.png

     

    The same image with a better resolution (more dots per inch), you may be able to guess what is depicted in the image

    RasterPalmeFein.png

    Given an image of a certain size, say 10 by 20 inches, the more dpi (dots per inch, think as pixels per inch) you have, the better the image resolution. For printing you should have at least 300 dpi, to present an image on a screen 72 dpi should be fine. So you are right, when you are printing an image you need a very fine resolution.

     

    But if you are asking how to preserve the quality of a digital image you already have on export, then the answer is simple: try to preserve all the pixels you have. That is what you will get, when you select one of the output presets with "original size". Those presets will export an image that has as many pixels as the one you are exporting, the other presets will subsample the pixels and give a poorer geometric resolution.

    It might be confusing to you, to be asked for dpi on export. On first glance this option is meaningless, since a digital image has no geometric extent, no height and no width in inches, it is just a collection of pixels.

     

    If you specify dpi on export, you will not change the number of pixels that image will have. You only provide data from which the size of the image can be computed, when it will be printed or displayed on a screen.

    Maybe now my previous example is clearer:

    If your image has 720x720 pixels, and you export it with 72dpi, then the image will be displayed with a size of 10x10 inches.  The same image exported with a resolution of 300 dpi will be printed as a tiny square of 2,4x2,4 inches.

     

    Besides the number of pixels it is important to pick a lossless codec, when exporting the image. Jpeg will only approximate the pixels, and the data loss depends on the quality setting, tiff will give you a lossless representation.

     

    If this still does not make it clearer to you, feel free to ask more.

     

    Cheers

    Léonie

  • léonie Level 9 Level 9 (72,215 points)
    By "clean Aperture" I mean a fresh install of Aperture.  I'm having problems with my computer and will be getting the hard drive replaced.  I am in the process of backing things up.  Besides the usual system-wide backups, I want to have a copy of all of my images--both masters and versions--that I can reload into Aperture or another program down the road, if I ever decide to do that.

    If you want to continue with working with Aperture, after you reinstall your system, make sure that the Time Machine Backup includes your Aperture Library, but also copy your Aperture Library to a backup disk, and save the master files elsewhere.

  • léonie Level 9 Level 9 (72,215 points)

    If you want to extract the master files from the library, as suggested by network 23, here is a screenshot on how to reveal the masters in the library.

    ctrl-click the Aperture Library, select "Show package contents" from the pop up menu, and you should see a structure similar to this:

     

    Your masters are stored in in folders grouped by year, month, date.

     

    aplibMastersPI.png

  • Terence Devlin Level 10 Level 10 (133,145 points)
    The problem with trying to use the Export command on your "masters" is that there is always a risk you will alter your "masters" with an errant setting, and then they won't be like masters anymore.

     

    What setting, exactly, would do that? I'm looking at the Export Masters dialogue right now and can see no option that could do such a thing. I can decide the location, naming formats and whether or not to include IPTC.

     

    Accessing the Library as you suggest is a: not supported and b: can easily lead to dataloss for an inexperienced user.

     

     

    Regards

     

     

    TD

  • stormlvr Level 1 Level 1 (0 points)

    Thanks so much for the replies and clarification.  So, is the dpi setting only for exporting to print?  If I leave it at the default 72dpi will there be any problems getting quality prints in the future from jpeg versions exported with that setting?  Also, I'm assuming that the dpi export preset applies only to jpeg and tiff and the like, and not to RAW masters--or am I wrong about that? If I choose "export masters", will aperture will export my masters just as they are?  Pardon my thick skull--I'm an old dog trying to learn new tricks in this digital world!

  • Frank Caggiano Level 7 Level 7 (25,715 points)

    I'll try one more time to try and dissuade you from this course of action. What you are doing is not only a waste of your time it is not the best way to go about what you say you want to do.

     

    First if you re-install the application the libraries you have now will continue to work, there is no need to make a 'clean' library. If you are having problems with your library then you need to address that issue. Start with the steps here Aperture 3: Troubleshooting Basics.  If you are having a specific problem then describe that problem and we may be able to help.

     

    As for backups, if you didn't backup your masters before importing into Aperture that's no reason to panic. If you've been running a managed masters setup the masters have been backed up when you backed up the library. If the masters are referenced then they are backed up when you backup the volume they are on. If you're not doing backups then you need to address that for your entire system, not just Aperture.

     

    Exporting every version from your Aperture library at a resolution that will make them useable for any future conceivable need is going to take up a tremendous amount of storage. The fact that you are asking aboutwhat  DPI to export at  for these images indicates a basic lack of digital image knowledge.

     

    Look at it this way say you have 10 masters and each master has 3 versions. That means you'll be going from 10 image files to 40 image  files (the original 10 plus the 30 versions). for those 30 versions t be useful in any real way in the future you will need to export them at original size either as TIFF's of JPG's at quality 12. You will basically be taking up 4 times the storage that you are using now.

     

    Finally these exported versions, while you could import them back into Aperture they will then become there own masters. There will be no conection between any of these versions and the original master or any of the other versions made from that master.

     

    Where as in the above example you had 10 images with 3 versions each, where those versions were tightly coupled to each other and the master tou will have, after your plan, 40 separate masters that have no connection to each other. You want to find that image of Aunt Martha? there could be dozens of (identical) images that have no connection to each other and therefore no way to search for them all.

     

    Again there are other better ways to do this using Aperture, that is after all the application you purchased.

     

    regards

  • léonie Level 9 Level 9 (72,215 points)

    I am somewhat reluctant to answer your questions after Frank Caggiano's excellent advice, but I really do not like to leave the question open, for there will be many occasions when you will need to export images and to understand how it works.

     

    But please, follow Frank's advice, right now you do not need to worry about pixels and dpi. That is exactly what I meant, when I suggested to you to make sure you keep a copy of your Aperture Library and to back it up with all your other data, before you erase your disk for a clean reinstall.

     

    DPI revisited:

     

    So, is the dpi setting only for exporting to print?

    The dpi settings are necessary to define the size of a digital image, since pixels don't have any dimensions. And since you cannot print or display an image without knowing its width and height, you will need to specify dpi when you are printing or scanning.

     

    If I leave it at the default 72dpi will there be any problems getting quality prints in the future from jpeg versions exported with that setting?


    Not if you export with the original size - the maximum number of pixels available. That will ensure the maximum print quality.

     

    The dpi settings are required to export versions; versions are derived from the masters and new image files are computed. When you export masters you get a copy of the original file that already may have a dpi setting.

     

    If I choose "export masters", will aperture will export my masters just as they are? 

    yes, and  you may add IPICT data if you choose

     

    Pardon my thick skull--I'm an old dog trying to learn new tricks in this digital world!

     

    No apologies necessary, we were all beginners once

     

     

    Here is another example, maybe that helps a little:

     

     

    I exported an image (jpeg) with three different setting: export masters, a version with 72dpi, a version with 300dpi and inspected the files in Graphic Converter:

     

     

    The master was exported like this:

     

    InfoMaster.png

    Notice, the master had already dpi settings, although I did not specify any on export.

    The size is 51,48 cm x 38,61 cm.

     

    The 72 dpi Version has larger dimensions, but also 10 Megapixels.

    info72sect.png

     

    and here the 300 dpi version: smaller dimensions, same amount of pixels.

    info300sect.png

  • stormlvr Level 1 Level 1 (0 points)

    Frank, thank you for your sound advice and description of how to manage backup with Aperture.  I fully admit to "a basic lack of digital knowledge".  I have done a time machine backup and a vault.  But, I also wanted have copies of my masters as well as my versions with all of my adjustments that would not require Aperture to access.  The idea being that, if I needed to completely reinstall Aperture from scratch or abandon it altogether, I would have the master images to reimport and the jpg versions to print, if so desired.  I have been having problems with Aperture, but have not, yet, gone through the troubleshooting steps.  Since I have a failing hard drive, I plan to have that replaced first, do a restore, then see what problems, if any, I still have after that.  At that time, I'll go through the troubleshooting steps outlined in the Aperture troubleshooting basics, if necessary. If I'm still having problems after that, I will definitely be back here for additional help! 

     

    Leoni, thank you so much for bearing with my lack of understanding regarding the dpi issue, and for rewording things in various ways to help me grasp the concept!  And, thank you for realizing that there will be other times when I will be exporting images and will need this basic understanding.

     

    Thank you also, Terence Devlin and Network 23.  Although, you did not actually answer my question, you did give me some useful advice and I appreciate it.

     

    I really appreciate that you all took the time to respond to my questions and trie to help me! 

  • léonie Level 9 Level 9 (72,215 points)

    You are welcome,

    and feel free to post back if you need additional advice when you reinstall your system.

     

    Regards

    Léonie