Why are Aperture exports to Photoshop so large?

Discussion in 'Digital Photography' started by TatsuTerror, Jun 29, 2012.

  1. TatsuTerror macrumors regular

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    #1
    When I export to .psd from Aperture (16 bit), I get a huge file, on the order of over 100MB. I'm not concerned, I'm just curious as to why it is so large, considering that's over 10 times the size of the original file (taken on a Canon Rebel series SLR). So, anybody know the process behind this?

    And, would I be losing detail/data if I exported as a jpeg or png or something instead?
     
  2. snberk103 macrumors 603

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    #2
    I'm not exactly sure of the technical ins-and-outs... but I'm guessing you are shooting RAW files. RAW files contain all of the data that the sensor captured. I believe that RAW files are also compressed, using a non-lossy algorithm.

    Aperture has the facility to work with RAW files, so you won't see the file size change if you stay in Aperture. However, editing programs can't work with RAW files, so Aperture "expands" the file into a format that the editing application can work with. All of the data (and remember that it is all the data that the camera recorded) needs to be packed into a file format that was not intended to record all the data from a sensor... so there are more "bits" created.

    If you exported as a JPG you may be losing data as it uses a "lossy" compression algorithm, not sure about PNG. Ideally - you should be doing virtually all of your editing in Aperture as it is working with the RAW data. You have much more latitude to make exposure and colour corrections when working with RAW rather than a .PNG, .JPG, .TIF or a .PSD file.

    Hope this kinda basic explanation helps...
     
  3. TatsuTerror thread starter macrumors regular

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    #3
    Would make sense for RAW, but the files in question were recording only in JPEG form.
     
  4. snberk103 macrumors 603

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    #4
    OK. Then I'm stumped and have no idea. :)
     
  5. Designer Dale macrumors 68040

    Designer Dale

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    #5
    What are the dimensions of each file? I just messed with a 34MB raw file that was 4217 × 2811 at 240 dpi or so. When I exported it to PS as a PSD, the dimensions were the same, but the resolution was set to 72 dpi changing the print width up to 58x39 inches. This took the file size up to 67MB. If I set the resolution in PS to 240, the print size changed to 17x12. With the lower dpi at the same pixel dimensions, PS is trying to make a huge print for you.

    Try exporting your jpg to PhotoShop and setting the resolution under File Size to 240 or 300 (print resolution) and see if the file shrinks.

    Dale
     
  6. mackmgg macrumors 65816

    mackmgg

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    #6
    PSD files also save a lot more information. Things like transparency, layers, even the editing history. And with modern dSLRs, these images are huge, from 15MP and up. Add in the fact that PSDs aren't compressed, and you get pretty huge files.
     
  7. msandersen, Jun 30, 2012
    Last edited: Jun 30, 2012

    msandersen macrumors regular

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    #7
    So the originals are jpgs? No point in exporting as 16-bit files then, as jpgs are 8-bit. jpg is also a lossy format, which is how it obtains such small files, whereas PSD or similar formats like Tiff or PNG are lossless, and hence take up more room. If you have Aperture export jpgs as 16-bit, you are inflating the size quite a bit with no gain. Only when exporting a RAW file would 16-bit make sense.
    jpgs should only really be for final files; they don't make for good intermediate files due to their lossy nature. The more you manipulate them, the more this will be obvious. Raw is great for serious amateurs to pros who want to tinker with their images to make the most of them, Raw being far more flexible than jpg, for instance able to recover highlight and shadow detail lost in jpg. Even so, RAW is not for everyone, the files are huge and if you shoot a lot, eats up a lot of HD space. If you're mostly happy with your photos as you shoot them as jpgs and only want to do occasional editing in PS, export as 8-bit Tiff files; still larger than jpgs, but nothing like a 16-bit file. When you save, you can save with Zip compression which works fine in Aperture.

    Depends on the format; Raw is not one format, it simply represents a file holding all the raw image data from the camera sensor. It varies with camera maker and individual models, which is why Adobe and Apple has to keep updating their Camera Raw database as new cameras are released. In the case of Canon CR2, they have pretty good compression. Adobe has proposed the DNG format as one single standard format, like a TIFF file for Raw files, it is also compressed, but so far only smaller independent makers are using it; Canon and Nikon are the market leaders and see no profit in open standards, occasionally even incorporating encryption into Raw files to stop 3rd party tools reading them, in the case of a Nikon camera. Same reason they don't want to work on a common open lens format, like the 2/3rds format.

    Raw files are high-bit formats, the size depending on the camera, but generally they fit nicely inside a 16-bit file; in the case of my Canon 600D/Rebel T3i, it is a 14-bit format. So exporting to 16-bit Tiff files for editing is no problem. but will be larger than the compressed 14-bit Raw files.

    PNG is a format similar to TIFF, originally intended to be a royalty-free replacement for GIF to get around the LZW patent, while also being able to do full-colour RGB images, and uses a compression technique a bit better than the default LZW compression used in TIFF. While PNG can handle high-bit images as well, I don't know about Aperture's ability to read those, I tend to use Tiff files with Zip compression, and when done editing, save back as 8-bit to save space. 16-bit PNG, Tiff or PSDs can hold all the image data and so are just as good for editing exposure and so on. The idea with Raw files in Aperture or Lightroom though is to have a Digital negative that you edit non-destructively.

    The fact Aperture exports as 72dpi is an issue for some exporting for print, but has no bearing on file size. It simply relates how large the image should be in the physical world, literally how many pixels per inch. If you go to image Resize and uncheck Resample Image, as you change the resolution, Photoshop changes the image dimensions in inverse proportion, with no actual changes being made to the image. It's just a number.

    PSD files are compressed. I find them more compact than Tiff files with compression.
     
  8. jdavtz macrumors 6502a

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    #8
    The file size and bit-depth that are used for exporting to Photoshop are completely independent of whether the original is RAW or JPG or anything else.

    They're set in Preferences -- see screenshot.
     

    Attached Files:

  9. jdavtz macrumors 6502a

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    #9
    Note that the "dpi" setting in that Preferences panel doesn't have any impact on file size; it's only to tell the receiving application how big the photo should be in the "real world" -- mine's set to 402ppi as that's what my printing company print at. The number of pixels (and therefore megabytes) in the file is completely unaffected by this.
     
  10. Dane D. macrumors 6502a

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    #10
    No, you are wrong, if the file size is 8 x 10 inches at 300 dpi, it is 20.6MB. Now if you change the resolution but not the physical dimension the file size decreases. An 8x 10 at screen resolution of 72dpi is 1.19MB.
     
  11. jdavtz macrumors 6502a

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    #11
    But we're not talking about exporting to a fixed size in inches at a specified ppi; we're talking about exporting a full-size image for further editing.
     
  12. Dane D. macrumors 6502a

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    #12
    Not following your logic, if I export a "full-size" image it has to have a given dimension at a given dpi. I shoot RAW with my Nikon and use Photoshop to convert to psd files. They usually convert to 240 dpi at a given size and then I change the resolution without resampling the file to get the "real-world" size. I deal mostly with images that go to a press for printing so my files are always CMYK, 300 dpi at the size I need them. I don't use 72 dpi and then resize them in InDesign to fit the layout. Also why is the OP exporting 16-bit, complete overkill.
     
  13. jdavtz, Jun 30, 2012
    Last edited: Jun 30, 2012

    jdavtz macrumors 6502a

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    #13
    Okay, my logic is:
    Aperture has original RAW file (or JPG, it doesn't matter), let's say 3000x2000 pixels.
    Aperture>Preferences>Export options let me set a format TIFF/JPG/PSD/etc. to export to Photoshop/Pixelmator/etc., and I can also set a "dpi" for the export.
    If I put "100" in the DPI box, Photoshop will receive a TIFF that is 3000x2000 pixels with a "size" of 30x20 inches.
    If I put "200" in the DPT box, Phothshop will receive a TIFF that is 3000x2000 pixels with a "size" of 15x10 inches.
    But both of these TIFF files have the same number of pixels, the same bit depth, and are the same size in megabytes.

    What we then do with the file in terms of resizing and setting DPI for printing obviously will change the file's size, but I believe this topic was really about the size of files exported Aperture > Photoshop, rather than the results of Photoshop transformations.

    I've just realised it's important to note that I'm NOT talking about a "normal" "Export" of a file (i.e. File>Export) and the opening that exported file in PS, but rather Aperture's built-in settings for "Edit with xyz editor". If you do a "normal Export" and set a size and PPI in the options dialog for that (i.e. don't set it to "original size"), then that WILL affect the image size (and quality). I think this is where our "disagreement" has come from.
     
  14. Ruahrc macrumors 65816

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    Jun 9, 2009
    #14
    It doesn't matter if the source file is JPG, RAW, TIFF< whatever, when you export to Photoshop for editing it uses the format you specify in the options. So even though it is JPG original, it saves a copy as full 16-bit TIFF and sends it to photoshop. That is why the size increases a lot, and the basis of the "nondestructive workflow" concept- it does not alter your original file, rather makes a copy and sends it over to PS.

    BTW, sending 8-bit JPG images in 16-bit TIFF format is not necessarily a bad thing nor is it overkill, as the extra bit depth and lossless file format give you extra headroom for edits. For example if you really start messing with colors, the extra 8-bits of depth will allow your edits to interpolate colors between the 8-bits of color in the source file, allowing you to achieve a smoother result.

    Ruahrc
     

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