Importing files into Aperture - Thumbnails, Previews and Jpegs

I don't want to go into this topic in too much detail as it is something that a lot of other sites have done and done well (for example here) but I do want to make you aware of what is happening when you import your photographs and the level of control that you have over it.

First of all Aperture generates thumbnails for each of the images that you import, the thumbnails are sized at 1024 on the longest side and this is one of the few areas where you have no say. Aperture will create the thumbnails for you at this size. 

The next thing that Aperture will do is to create previews, the difference between thumbnails and previews is that the thumbnails are only visible and accessible within Aperture, whereas the Previews can be used in other programs, for example they can be dragged to the desktop or imported into Pages and Keynote and so on. The Previews can also be set to a much larger file than the Thumbnails and so be easier to work with, the disadvantage of course being that the previews will increase your library size. There are two ways to work with this though, you can set a size limit for the previews and a quality level or you can switch previews off and then switch them on again for specific projects or you can do both at the same time. Note that by default the previews are set to on, globally.

So first of all, how do you reduce the size of the previews? You need to go into Aperture's preferences and click the previews tab.

From here you can decide if you want to share with the iLife and iWork applications, set the quality level (personally I have 7 to be a good compromise between size and quality, over 7 doesn't seem to bring much benefit compared to the size of the file) and finally you have the photo preview menu, which if you select it, offers a list of sizes that you can use.

The asterisk in the menu shows your current screen resolution. Half size is the default setting, I read an Apple paper, that unfortunately I can't find the link to right now, stated that for images up to 8mp, the recommendation was to leave the setting alone or evenchange it to don't limit. Over that size, if you are working with RAW images for example, then selecting one of the other options above, can help to keep your library size down.

If you decide on the other hand that you don't want to generate previews for all of your projects by default, just the ones that you select, then still in the same preference window, you will see the option "New projects automatically generate previews". Turning this off mean that no previews will be generated for that project or any other project when you import them into Aperture. Afterwards if you would like to have previews, then you can generate them for that project manually or alternatively you can delete them for existing projects.

The way that you do this, is as follows;

In Aperture, make sure that the library tab is selected on the left and pick the project that you want to work with the previews for, in the righthand window, (switching to browser may help here), select all of the photographs by pressing CMD-A and then right click on any photograph and a menu will appear from this menu choose either update previews to create them or delete previews to remove them.

Remember the main advantage of the previews is having decent versions of the photographs available if your main library isn't online (you have a notebook and the masters are on an external drive for example), having high quality images that you can use for a presentation or a demo (1920 is HD resolution), being able to drag the images into another application to work with and making it easier for you when you are working in Aperture.

Finally concerning RAW photographs, if you go back to the Aperture preferences and select the Preview tab, you'll see an option "use embedded jpeg from camera if possible", if you have this enabled and your camera generates a jpeg image from the raw file as you photograph, then this jpeg will be copied into the library immediately, it is a fast way for you to go through the library and start sorting, grading etc, while the larger raw files copy over. Once the raw files have copied over, the image will be refreshed.

I plan on leaving the previews on for now and seeing what happens, in the future I will adjust my plans accordingly, as I can always delete and or generate previews if I need to.