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CS6 File Sizes

Feb 22, 2013 3:03 AM



In general, I save my documents as uncompressed TIF files. On a recent project I have noticed that the files being created appear particularly large and are significantly bigger than the size indicated in the status bar.


An example:


Document is 16-bit RGB with Background layer, copy of background layer, a new layer that contains a small amount of retouching work and 3 curve adjustment layers.


Status bar shows Doc 223.3M/502.1M.


Saved file size as uncompressed TIF is 1.22 GB. This would seem rather large to me, considering how many layers are in use. Perhaps I have just overlooked the size of files generated before. I do note that deleting unused layer masks reduces the size of the saved file to about 989MB.


I saved the file as a PSD for comparison and the resulting file is 611.7 MB (with Maximize Compatibility turned on).


So, I am wondering if the above is considered normal and, if so, can anyone clarify exactly what the second figure in the status bar shows? Does the size displayed in the status bar refer to the document size when saved as a PSD file (rather than uncompressed TIF), is it merely an approximation of the saved file size, or do have an issue with my installation of Photoshop?


For information, I am using Photoshop CS 6 Extended (13.1.2) on OS X 10.8.2.


If anyone could clarify the situation for me, I would be most grateful.


Many thanks




Forgot to add that I am not using any smart objects.


Message was edited by: LDJ

  • Currently Being Moderated
    Feb 22, 2013 4:18 AM   in reply to LDJ

    Quote from the reference:

    Document Sizes Displays information on the amount of data in the image. The number on the left represents the printing size

    of the image—approximately the size of the saved, flattened file in Adobe Photoshop format. The number on the right

    indicates the file’s approximate size including layers and channels


    What are the pixel dimensions of the image in question?

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  • JJMack
    5,979 posts
    Jan 9, 2006
    Currently Being Moderated
    Feb 22, 2013 5:56 AM   in reply to LDJ

    It make no difference as to what your using. Its what you doing the make for large size and something does not seem to add up right.  Uncompressed mean your recording ever pixel color value.  If you have an image that is 3000 px by 2000 px that is 10,000,000 pixels if its a RGB image there are three color values for each pixel.  If 8 bit color 3 Bytes per pixel if 16 bit color 6 bytes per pixel. If you saving a layered tif Photoshop needs to record every layers pixel values and layer sized can vary the can contain more pixels, less pixels or the same number of pixels as canvas size.


    So lets say you have a 20Mpixel camera and you shoot RAW and convert to 16Bit ProPhoto RGB color space  your image start life as a 120,000,000 byte pixel normal raster layer you dupe that layer you now have 240,000,000 bytes you add three adjustment layers each these comes a single channel layer mask which adds up to an other 120,000,000 bytes so now your only up to 360,000,000 bytes of pixel data metadata is small compared to pixel data. 


    So I repeat the above question posed to you.  What is the Pixel size you have for the Image Layer. 


    The status bar sizes have nothing to do with file size. Photoshop is a document editor not a file editor.  I would think those sizes would represent more the memory Photoshop is managing your image in.  Besides the memory required to manage the pixel data Photoshop also needs additional memory for rendering a composite view and also memory for the scaled view it displays to you..

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  • Currently Being Moderated
    Feb 22, 2013 7:30 AM   in reply to LDJ

    My guess is that the document contains a slightly cropped 40 MP (7264 * 5440) 16 bits per channel RGB image.


    When saving to layered TIFF, the composite image compression is independent of the layers compression. Layers should always be compressed. However...


    In 16-bit mode, only ZIP compression of layers is honoured. The choice of RLE layer compression results in no compression of layers. (Both RLE and ZIP compression for layers are honoured in 8-bit mode.)


    You have composite image compression set to None. I suspect you have RLE chosen for layer compression (which is not being honoured), resulting in 989 MB.


    Something like this is in your file:


    Composite (3 channels), uncompressed = 223.3 MB

    Background (3 channels), uncompressed = 223.3 MB

    Background copy (4 channels), uncompressed = 297.7 MB

    Retouch (4 channels), smaller than canvas, uncompressed = ~245 MB

    Curves 1 = trivial

    Curves 2 = trivial

    Curves 3 = trivial

    Metadata = trivial


    Maybe you have some masks and the retouch layer is smaller than I've accounted for.


    Anyway, if you choose ZIP for the layer compression then a smaller file should result. That will not affect your choice of no compression for the composite image.

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  • JJMack
    5,979 posts
    Jan 9, 2006
    Currently Being Moderated
    Feb 22, 2013 9:02 AM   in reply to LDJ

    I do not think the status bar sizes has any relationship to any file size. Image file formats differ greatly in what is supported compression layer types transparency alpha channels etc. Compression size depends on content. Since Photoshop large file support is PSB it uses compression PSB would be the format choice and any value Photoshop could display for file size would just be a shot in the dark..

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  • Currently Being Moderated
    Feb 22, 2013 9:37 AM   in reply to LDJ

    LDJ, the Document Sizes status numbers have nothing to do with file sizes.


    The left number in the status bar is the memory consumed by an uncompressed flattened composite:

    width pixels

    x height pixels

    x number of colour channels

    x bytes per channel


    As far as I can tell, the right-hand number is supposed to be the total memory consumed by all layers, adjustment layers, fill layers, masks, alpha channels, etc. Smart Object layers are not included at present, which seems like a mistake. The data for a layer can be much smaller than the pixels which are rendered for the layer, so it's possible for the left number to be the larger one.

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