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Thread: Image vs doc size

  1. #1
    Join Date
    Nov 2009

    Default Image vs doc size

    macpro 2 x 2.66 GHz duel core intel-duel core xeon

    I have a jpeg 8 x 10 1440 res that shows a doc size (bottom left of file ) 474.6m but, when I close the file to a folder it shows 27.4 mb system runs somewhat slow history is empty and is set to allow 10 files.

    the same file in psd form shows the same doc size!

    I have the application in a second hard drive that has an unused 400 gigs.

    I have the folder with the files in an external HD w/unused 387 gigs and am using this as my scratch disc. and I have allotted 3000mb to photoshop cs4

    any idea's on how to clean up/speed up my system would be greatly appreciated!

  2. #2
    Join Date
    Jun 2008
    Phoenix, AZ


    That's a big image!

    Photoshop is all about RAM. How much RAM does your system have?

  3. #3
    Join Date
    Dec 2003

    Default Image vs doc size

    PSD's are almost always enormous in comparison to a JPG, PNG, or GIF of the same dimensions.

    As for dimensions, unless it's necessary to retain a very high PPI (600-1200+) there is rarely anything that will cause me to keep it at a scanned size.

    I have a CanoScan 4400F which will scan an 8.5 X 11 page at 300PPI to a size of 2550 X 3300 and I usually take that down to about a quarter if the original size or 640 X 828.

    The difference in file size is 24.1 M to 1.52M when I do that.

    It's all about the resolution and clarity you desire for the final document in my experience. I just don't have need for 1440 PPI at 2550 X 3300. If I were a forensic photographer, maybe, but I'm just an amateur.

    To coin a phrase, "size matters".

    Two examples:

    My sister-in-law loves to take pictures of everything with her 8 megapixel digital camera. Then she loves to send them to everyone she knows. With a 2.5MBPS cable connection she sees nothing wrong with uploading eight or ten 2.5 Mb jpgs at 2048 X 1536 resolution and sending them to people with laptops, and some still on dial up. It's been years since I tried to download 48 megs of anything on a 56k modem, but it must be torture to click on one of these mails and have your system lock up while it tries to register and preload the attached files before it opens. I finally showed her how to "resize them" so that they weren't posters and the size of MP3's.

    My dad was using HP Photosmart to scan legal documents as JPGs. At 300PPI, he was saving them as 24.1Mb documents. (24.1Mb apiece) He had about 150 pages done when he noticed a sizable chunk of hard drive space gone. 3.5 gigs was taken up just with this one folder, and he had about ten folders to do at 150-200 pages each, so he called me. Dad has Acrobat 9 Professional but he never bothered to open it because he was afraid he wouldn't know how to use it. I re-sized all of his documents in Photoshop and saved them as PDFs, then ran OCR on all of them and merged them with Acrobat into three 50 page PDFs at about 3Mb each. 3.5 Gigs down to 9 Megs. The quality is indistinguishable between the original and the "smaller" ones, and with the OCR, he has the ability to copy and paste selections to Word if he needs to.

    As a part time web designer, I need upload files to be as small as possible, because sometimes I'm working with wireless in a restaurant when changes go up to one of my sites. A 1.5 Mb JPG can cause Dreamweaver to time out before the file goes to the server. A dimensionally equal GIF is only about 85Kb and goes up instantly.

    Photoshop is the same way. The smaller the file, the faster it loads and saves. I have done some logo design that requires large (1920 X 1080) PSDs with sometimes as many as 35 layers before the design is complete. The biggest was 156Mb before the customer was satisfied and I could finally save it. It took about three minutes for Photoshop to load it when we needed to go over something as I built it. The finished logo was 1.2Mb as a JPG and 675Kb as a GIF. They were much easier to work with (for web page and letterhead insertions) once the file was saved in a smaller format and size.
    I'm reminded of the immortal Socrates who said......."I drank WHAT?????"

  4. #4
    Join Date
    Nov 2009


    I have 5 GiGs of ram

    the reason for the 1440 resolution is that I am printing on an epsom as opposed to a HP (720 resolution) and need to print at 1440 LPI (lenticular) to create 3D images.

    My confusion is that if, as a saved file jpg It shows as 27mb

    a. why as an open file would it show as 474mb and;

    b. why would it show the same size in psd?

    does it have something to do with the fact that;

    a. one is a working file that is pulling from the system vs

    b. one that is a saved file and just sitting on my desktop


    c. that when open the jpg and psd are both the same size and both the same resolution therefore the same size mb, and the only thing I can do is get more Ram?

  5. #5
    Join Date
    Nov 2004



    sorry to chime in here but, 1440DPI (not LPI) is pretty high resolution and input resolution hasn't to be equal to output resolution...

    DPI=resolution, LPI= raster/screening frequency

    For example... for a 2400DPI, 150LPI output on an imagesetter the best result you'll get with an input resolution of 300DPI (LPIx2= input DPI) for screened/rasterized CMYK images and 900DPI for bitmap images or lineart (as long those are not in a vector format like EPS). Inkjet printers are using a non static raster instead they are using a cellsize called layer.

    1440DPI output resolution : by the printers cell size with is 5x5 = 288DPI input resolution

    Input is not the output resolution. An inkjet printer uses a frequency-modulated screening to produce the output which is addicted to the cell size. A to high input solution could degarde the output quality as much as a to low resolution. BTW I couldn't see any difference between 2880 and 1440 DPI on inkjet printers, besides those are non real DPIs like on an imagesetter.


    Last edited by Nicolas; 11-29-2009 at 11:38 AM.
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