I don’t think you want a technical explanation of why of why NO SOFTWARE does what you were asking – They all build JPEGs from scratch.

I also don’t think you want a technical explanation of what you are looking at on your scree. Let’s just say it is not a RAW image, it is Not a JPEG it is not a TIFF. They are all file formats that contain data that can be turned into an image on some output device – you are looking at none of them really.

RB

Ps. If you really really want to KNOW how all this stuff works at a very low level feel free to sign up for a one on one session – Not that it will change the way you do anything nor is there much you can do with that information.

RB

I am not going to answer all of those in order or even completely. Previews can speed up Aperture in some things but definitely not all. If the previews are smaller than your screen resolution they are almost useless inside Aperture for many reasons. You may want to fine tune your preview generation for only really good images that you NEED previews for. Re-read your copy of the file management eBook.

When previews are off you see things as real-time as it gets – you see it the when they are on as well. Preview generation and use is a parallel activity to rendering on the screen. From what I can see Aperture sometimes uses the preview if it is there to speed up flipping through images and definitely uses it in quick preview mode.

I never ever use maintain previews for project – it is always off. I manually generate them from a selection. That selection is made in lots of different ways at various levels in my library.

Trivia item If you use your head you can use the manual method to maintain multiple sizes of previews for different sets of images – not that I do but I can.

RB

RE Previews: The most helpful advice as far as speeding up my workflow was your original post on previews and toggling them off while editing, and setting maximum resolution no bigger than your display. If I remember correctly you used 1920 because it corresponded to the projector you use for slide shows & workshops. I use that also because I use 2 22″ Cinema Displays with one dedicated to full preview.
For personnal work, I shoot digital like film, economical, single shot, and will often see a picture, raise the camera to my eye, and decide not to press the shutter. Even then, if I edit honestly, somewhere between 1 in 10 and 1 in 50 needs to be edited through to a print.
For commercial work especially event type work somewhere between 1 in 2 and 1 in 4 make the cut to be edited and passed to a final cut before being presented to a client.

I have always tended to edit sequentially from first to last (especially in event work) so my workflow has been:
Import to Aperture in a new Project, then Backup Cards to a separate drive etc ehile Aperture builds Previews.
When Previews are done, I create a simple smart album for images with 1 or more stars.
I start editing with image #1 and go through them sequentially.
Any image that I edit gets 1 star and then appears in the smart album. I have maintain previews off while editing, each time I take a break, I turn previews on and let it catch up.
I may also create a second smart album for noteable pictures and give them 2 stars (This doesn’t remove them from the 1 or more album.
I go through the 1 or more album quickly full screen to look for anomolies or mistakes. Then I can convert and export in various formats from 640 JPGs to 8 bit Tiffs.

With these 2 workflows (which may be flawed to begin with) I have some questions.
1. Obviously with previews “off most of the time” as you describe above, can we assume that this is one of the reasons that you don’t experience the speed issues or Maroon screen, that many of us have?
2. How do our choices in generating previews – size chosen , or no previews at all, affect what we see on the screen, and speed of Aperture.
3. When “Maintain Previews for this Project” is deselected,
and we edit, we do see our changes in near real time.
What is this image? It must be by definition a preview, but is it not saved some where? Because if Aperture is up to date on all previews, and there is no activity in the “Activity Window”,
and I turn off Maintain PV, and select and edit an image, I see those changes on my screen (a preview of what my edit will look like). But, if I then toggle Maintain PV back on the Activity window will show “building 1 preview” and it is far from an instaneous process -15-45 seconds, so it’s not a trivial amount of work for the machine.
What’s going on here?
4. As a corrolary to the above, is having previews already built from the raw files at screen resolution (1920) a “leg up” for the edited preview and thus help the speed of the process, or does Aperture start my edited preview “from scratch” or does it build upon the Basic raw preview that I generated at the begining of my workflow.
Or, if Aperture does Evertthing from scratch, why should we EVER build previews until after we have selected and edited images?
5. And finally, I can see how in my “Personal work” where I’m selecting far fewer (1 of 10) how not builsing any previews until an image go 1 star and was moved to a smart album should be more efficient.
In the “event workflow” I find I reallt need to start editing some of the images before I decite it’s a keeper, so is allowing aperture to build 1920 previews doing anything to speed the editing process?
An understanding of the how & why would be very helpful
Thanks Michael