During a recent photography course in South Africa I was strongly advised to download and use free Raw Processing Software before editing in Aperture 3. As a relative newcomer to working in Raw, I had not previously been conscious of the difference between Raw Processing and editing and have been processing and editing Raw files in Aperture 3 (on an iMac with OS X Lion).

By way of rationale, I was told that unprocessed Raw files contain separate layers of colour whereas files opened in Aperture 3 will already have had those layers compressed into one layer, presumably meaning that any alteration to green would also alter blue and red etc and vice versa. Shooting on a Canon 7D, I have tried on returning to London to download and use the DPP software for Raw processing but have immediately encountered a block indicating that it is not suitable for use with my iMac software (though the DPP software does claim to be compatible with MAc OS X version 10.2-10.8.)

I fear that I may have misunderstood what I was advised in South Africa as, even if I could could get it to function, this workflow pattern of using Canon's raw processing software prior to using Aperture 3 does seems inordinately complex and time-consuming. What (if any) harm would I be doing to my Raw images and/or what would I be foregoing if I simply reverted to my previous practice of downloading my Raw images straight into Aperture 3 and processing / editing them there?

  • \$\begingroup\$ This makes no sense at all. \$\endgroup\$
    – Itai
    Commented Feb 15, 2013 at 1:05
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    \$\begingroup\$ @Itai his question(and there are a few points in there) or how he asked it? I understand that he's a little confused over what he has been told. \$\endgroup\$ Commented Feb 15, 2013 at 1:33

1 Answer 1


You simply got misguided advice. It sounds like the person you were talking to didn't realize that Aperture is RAW conversion software. The issue of color demosaicing (with your camera, as with most, it's not really layers, but rather side-by-side in a Bayer pattern) would hold if you were going to a traditional raster editor like Photoshop or Gimp, but if you open the file in Aperture, you're not.

In fact, if you would go from Canon DPP to Aperture as suggested, by converting to JPEG in the first program and importing that, you'd actually be doing the "bad" thing, since Aperture wouldn't be working from the unconverted data. So, you don't want to follow the advice you were given.

That said, Canon's software does have different algorithms and different presets from Apple Aperture. You may find it easier to get results you like in Canon Digital Photo Professional. (See a similar question on Canon DPP vs. Lightroom.)

As a general rule, the RAW conversion software camera makers ship is tuned to produce results more similar to that same camera's JPEG engine, which many people struggle to reproduce in their third-party RAW software. In that case, you might decide you don't need Aperture at all. But it doesn't sound like that's true for you.

  • \$\begingroup\$ Vmny tks to mattdm. ( Would give maximum votes if I knew how.) Course moderator not misguided but referring primarily to Photoshop and I didn't enquire sufficiently about Aperture. I propose now to continue downloading Raw files directly into Aperture on basis that choice between Canon DPP and Aperture is swings and roundabouts and makes minimal difference at my level. But I'd still like to understand whether (a) there's any real practical difference between PROCESSING and EDITING Raw, and (b) whether my Raw images could suffer any harm by direct download into Aperture not using DPP first. DG \$\endgroup\$ Commented Feb 15, 2013 at 15:11
  • \$\begingroup\$ Mattdm, maybe u can help me again ? My Apple Aperture 3 ( fully updated ) simply won't upload raw files from my Canon 7D. Instead it displays 350 assorted images ( including corporate logos and the like ) attached to emails sent to me by others over a long period ; all attempts to cancel this unwanted upload fail and are overridden and the the Canon 7D input image disappears every time. A similar scenario occurs when uploading Jpegs or Raw + Jpegs but I have usually been able to overcome the problem. Is this a rectifiable fault on my Imac , in my Aperture software or in the Memory Cards ? DG \$\endgroup\$ Commented Feb 21, 2013 at 21:00
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    \$\begingroup\$ @David: that I have no idea about. Try asking as a new question... Maybe someone else knows. \$\endgroup\$
    – mattdm
    Commented Feb 21, 2013 at 22:20

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