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Thread: Resizing Question

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    Resizing Question

    An old topic that still puzzles to a degree....


    My brother-in-law has just had his first book published and needs a picture of himself for the back cover sleeve, seems easy enough. He took a few shots with his P&S Canon digital only to find they were rejected as the size was too small. The publishers reset the original dpi to 300 but the image apparently was then the size of a postage stamp ? { not sure what the original dpi off camera was though }

    Seems the publishers want maximum file size and a minimum 300dpi, fair enough but that does seem to be an overkill for a tiny portrait picture on the back of a paper back crime thriller ?

    Being a Canon I'm not sure what's what on this camera, but it's 10mp and straight off camera surely the dpi would be at least 200dpi and surely good enough for a tiny portrait for a book cover He has only the basic editing program that came with the camera.

    Talking to my B-I-L I advised him to set his camera to maximun jpeg quality, but he says he cant find anything relevant to that in book or camera ??? I then asked if he has set the picture size to large and it seems maybe he had it set to small and maybe that is the reason the publishers rejected the images, at small the images only had pixel dimensions of about 640 x 430 or something, that sounds about right I think. OK, so now he says he has set it to large and it says on camera the pixel dimensions is something in the order of 3460x 2130 { or something like that } but not sure of the dpi. When he now downloads the images to his PC they still say pixel dimensions of 640x 430 ??? ....unless he didn't set it properly on camera.

    So I guess this is my question......if he sets his 10mp Canon to large picture surely the dpi and pixel dimension file size straight off camera, no editing or resizing is more than enough for a small book back cover portrait shot ?...and why in the world would the publishers request minimum of 300dpi, and I wonder what dpi the images would be straight off camera anyway.

    Maybe I should get him to send the images to me and see what I can work out.

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    The 300dpi requested will probably be because it is being printed on an Industrial printer using software that only handles images at that resolution as a minimum for ease of page formatting.
    If he sent them a 640x430 that would be just over 2" on the long side, he needs to find out how to change the image size to one that is at least 300 times the required inches of the image.
    As an aside, the res of 3460x2130px would print out to 11.5" x 7.1" @ 300dpi.

    Cheers David
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    Hi Colin

    If he sets the camera to maximum image size which you say is 3460 x 2130 pixels then that should be more than enough for reproduction requirements. That should produce an image 29.29cm x 18cm at 300 dpi(dots or pixels per inch)......is that big enough for the portrait?

    Printers usually like their images to be at 300 dpi so that the designers can play with them a bit and crop a little if required. In effect 240 dpi is fine for high quality offset printing.

    Most digital cameras produce files out of the camera at 72 dpi and with large dimensions!

    It should be a simple matter of resizing the image in his editing program to get the required size. Not sure how it works there but it should be very similar to photoshop.

    First step would be to open the image size dialog box.

    You want to change the dpi to 300....BUT you DO NOT want to resample the image....probably a check box.

    After you have done this you should have the maximum printable size at 300dpi and it will probably show you the dimensions in cm.

    So now you have the maximum size......but I think the photo you need to print needs to be much smaller......so you will now have to throw away some pixels by resampling. Should be a resample image box to click, and then enter the dimesions of the image you need, constrain the proportions and click......you should now have the right sized file.

    Even 640 x 430 pixels will be enough if the final printed size is less than 5.5 x 3.6cm.

    Not sure how they want the file.....RGB is ok as long as you stress to them that you have supplied it that way and they need to change it to their own profile for printing.

    hope this helps

    Good luck
    Last edited by saratoga; 28-01-2009 at 1:05pm.
    Greg

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    Colin,
    Just a thought, if you find out the make and model of the camera you should be able to download the manual from the canon site and then step him through the process of getting the correct settings.

    Not 1005 sure of the dpi off camera for my little Canon p&s but i will find the book and look when i get home this evening
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    Maybe they want a larger photo for advertising, Book signings etc...

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    Thanks everyone, I think he has now sorted out the camera menu and set the largest size, but his other problem is he has no proper editing program to do things like alter dpi...I'll get him to send me the images and I'll alter them in CS3...but huge file sizes to send via email.

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    He probably set the file size to largest, but didn't save that setting correctly.. my sister does that all the time!

    Don't need an editing program, just saving as a jpg onto the PC as is.. the file that gets saved to the PC has no relationship to DPI. It's saved as a 3460 x 2130 pixel image and that's enough.... the printers software handles the technicality of DPI at the print stage.

    As saratoga said should equate to roughly 30cm x 18cm in print at 300DPI.

    10Mp jpg should be roughly equal to 3Mb or so.... give or take a meg or so.
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    Ok rather than open a new thread i would also like to no something.one of my panos at print size at 72dpi will enlarge to 121 inches on the longest side now thats one big pic,now at 300dpi it will enlarge to 29 inches on the longest side.

    so does this just mean at 300dpi there will be more pixels per inch resulting in a cleaner sharper image? cheers.

    steve.

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    Steve,
    don't get pixel res and dots per inch confused, they are two different types of measurement, the pixels are just that, say 3000x2100, the dots per inch are what the printer prints the image at, so if you printed those pixels at 300 dpi you would get a 10x7 inch image, but if you printed it at 600dpi you would get a 5x3.5 inch image, you could also tell the printer to adjust the image to a certain size, say 6x4 for the standard small photo size, that would give you 500 dpi and you would lose a bit down both sides

    Cheers David

    ps, an image printed at 72 dpi would look terrible
    Last edited by pommie; 29-01-2009 at 1:03am.

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    Why is this so?

    My Nikon D200 captures images at 300 dpi and 8.6 x 12.9” The Canons I have played with lately capture at 72 dpi and about 78 x 52”. Did I change my Nikons when I first set it up to record 300 dpi? Or is the imaged resized when I down load the images?

    Why do cameras capture images at 72 dpi and large dimensions when 300 dpi is required when printed?

    I have also notices film developed and save to disc have large dimensions and 72 dpi; Why? Why not 240/300 dpi and smaller dimensions? I crop/resize images 300dpi.

    Cheers

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    Moderately Underexposed I @ M's Avatar
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    Quote Originally Posted by IanB View Post
    Why is this so?

    My Nikon D200 captures images at 300 dpi and 8.6 x 12.9”
    Ian, your camera has no setting to alter DPI, in fact DPI does not enter into the equation until you open the file in whatever editing program you use.

    Cameras capture images measured in pixels measured on the x and y axis and multiplied to form megapixels.

    If you are shooting in JPEG on the D200 you have the choice of setting both the file size and quality in the menus.

    If you are shooting in NEF on the D200 you have the choice of setting the file to either compressed or uncompressed.
    Andrew
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    Quote Originally Posted by I @ M View Post
    Ian, your camera has no setting to alter DPI, in fact DPI does not enter into the equation until you open the file in whatever editing program you use.

    Cameras capture images measured in pixels measured on the x and y axis and multiplied to form megapixels.

    If you are shooting in JPEG on the D200 you have the choice of setting both the file size and quality in the menus.

    If you are shooting in NEF on the D200 you have the choice of setting the file to either compressed or uncompressed.
    Thanks Andrew; it's one of these things we do most days and never think about it until we do something a little different; and for me that was use the Canon.

    Cheers

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    Quote Originally Posted by IanB View Post
    Why do cameras capture images at 72 dpi and large dimensions when 300 dpi is required when printed?
    Quote Originally Posted by I @ M View Post
    Ian, your camera has no setting to alter DPI, in fact DPI does not enter into the equation until you open the file in whatever editing program you use.
    I would even go a step further: DPI does not enter the equation until you print it. In editing, on screen, dots per inch have no meaning whatsoever (not to mention the difference between DPI and PPI).

    My advice: forget about DPI - it's completely useless. All you need to know is how many pixels are required by the printer to get you a good looking picture. Any printer (I mean the guys, not your at-home pixel-pooper) saying "your image isn't big enough" when sending a 5 MPixel image or more for a paperback-cover doesn't know what he is talking about. And, seriously, he could so with half that resolution (150 DPI for this type of commercial printing is more than enough).
    Ciao, Joost

    All feedback is highly appreciated!

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