Is anything lost when you export from (Canon) RAW files to TIFF?

For context: I backup and archive my RAW files, and keep a separate (Aperture) library for exported JPEGs. So far my workflow has been in Aperture (edit the RAW, export to JPEG), and that's fine.

However, I really like what the DxO Optics Pro software does (where it improves sharpness, distortions and CAs on a lens by lens basis), but obviously you can't export a RAW file into Aperture. It needs to work on the RAW, so it's adding a step to the process, as it doesn't have the library or editing features of Aperture

I tried the DNG format, but get files sizes over 150MB! (Compared to 25MB RAWs)

It seems that TIFF is the best option, but will I loose things such as the ability to bump the exposure 2 or 3 stops? (More applicable to highlights/shadows, but I assume that's the same principle.)

Are there any other more subtle things I would loose for editing?

  • DNG file size shouldn't differ much from RAW file. Read this paper: Raw as Archival Still Image Format: A Consideration. The author is talking about the advantages and disadvantages of using DNG as an archival format
    – K''
    Jun 5, 2012 at 14:22
  • My results when I export from DxO are much bigger in DNG, at least 5 times bigger than the original file. I'm not commenting on the format per-se, but what DxO exports in that format.
    – AlastairC
    Jun 5, 2012 at 15:24
  • @Akram DXO is probably exporting a 16bit three-colour-per-pixel DNG with no compression, which will be about four times the size of a 12bit one-sample-per-pixel RAW file. With RAW compression a five fold increase is possible. TIFF allows lossless compression which should result in smaller files.
    – Matt Grum
    Jun 5, 2012 at 15:50

2 Answers 2


Provided the TIFF is 16 bits then you wont lose much editing latitude compared to the RAW file. What you want to do in DxO pro is develop the RAW for further editing, by reducing contrast to ensure that neither highlights or shadows are clipped. If you do it right the image should look really dull. Don't worry though - you'll be viewing the image on an 8bit device, there will be plenty of detail there to be developed when you finally process the image in lightroom.

You want to also aim for a neutral colour balance in DxO to avoid clipping any colour channels, giving yourself the maximum tonal range possible. Obviously having DxO sharpen you images will limit your editing options with regards to sharpening / noise reduction.

  • Thanks, that sounds like good advice, I probably up the colours/contrast too soon, I'll leave that until after DxO.
    – AlastairC
    Jun 5, 2012 at 15:26
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    It would be useful for the phantom downvoter to explain their vote. Jun 7, 2012 at 4:09
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    Would you be so kind as to elaborate on what exactly is lost when converting from RAW to TIFF? I have the same question as the title, but your answer doesn't really go into the loss, but more into the specific problem the OP has. I feel that asking a separate question would not be desirable. Apr 22, 2013 at 7:43

By exporting to TIFF (and any other format using RGB pixels) you lose the ability to use different demosaicing algorithms. Demosaicing influences noise reduction, picture sharpness and false color (moire) reduction.

The future color and exposure manipulation is not affected (assuming sufficient bit depth - 16 bit TIFF).

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