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Problem supplying artwork for picture book cover at 1200dpi

Discussion in 'Printing & Print Design Forum:' started by purelimejuice, Mar 26, 2013.

  1. purelimejuice

    purelimejuice New Member


    Hoping someone can help (I'm an illustrator starting out on book cover design)

    I'm trying to supply artwork to a printer for a picture book cover, for which all images etc. need to be at 1200dpi. I've imported images into the Indesign document, and added text in Indesign, but for the spine, I've imported psd files for a series font (image) and the publisher logo (image), which I had sized to 1200dpi in photoshop, when I export the Indesign file to PDF (High Quality Print) the printer says the images are 300dpi. The printer suggested the following:

    'the series logo and your logo are in 300dpi, you have to put these two items in bitmap before generating the PDF, it will probably solve the problem'

    I don't know what this means - to change the mode to bitmap in Photoshop before importing them to Indesign, and if so, what settings should I give in the Bitmap dialogue box?

  2. @GCarlD

    @GCarlD Well-Known Member

    I think it is telling you that although you may have set up to be at 1200dpi, your images are in actual fact 300dpi. Exactly what kind of images are you working with? And how exactly did you size them to 1200dpi? You know you can't add more pixels to an image that is originally lower dpi than you require. Saying that, 1200dpi seems a bit excessive. Is this book going to be the size of a billboard!? 300dpi should be fine for a book cover.
  3. purelimejuice

    purelimejuice New Member

    Resolution issue

    Hi CLHB, thanks so much for your answer -

    Basically, the French publisher of the book has asked for all images to be supplied at 1200dpi, which I thought seemed excessive too, as I've done six book covers in total now and all the others have been fine at 300dpi, no problems, even with illustrations. I did look up online about this issue and it seems that other people have been asked to supply 1200dpi artwork for illustrations as well so it's not a one-off case.

    For the images, I resized them in Photoshop, having unchecked the 'Resample image' option in the Image resize dialogue box, which reduced the over all size of the image, but upped the resolution to 1200dpi (is this correct?). For the barcode, on opening it in Photoshop as an EPS file, I resized it there to 1200dpi and the correct dimensions for placing it on the cover in Indesign, in order not to have to manually resize and distort the barcode. The French publisher (who are the ones telling me to supply in 1200dpi) suggested changing the objects to bitmap before exporting to PDF and this is where I've become very stuck as I don't know anything about bitmap - saving images as bitmap.. Thanks!
  4. Andy C

    Andy C New Member

    I don't think in all my years I have ever had to do anything at 1200dpi, and I have done some pretty big stuff....

    If you have sized your image to 1200dpi (without re sampling) then it will become much much smaller as the pixels cover less area. i.e a 300x300mm image at 300 dpi becomes only 75 ish mm at 1200dpi. If you re sample then the image will remain the same 300mm size and gain extra pixels that photoshop puls out of the ether to stuff in the gaps.

    In indesign when you export your document as pdf the settings there on default print settings actually resample the images down to 300dpi. When you export your document you will need to goto the compression settings, there is a pull down menu that normally is set on bicubic downsampling and next to that the resolution, and below the images that its applied too. i.e if you have imported an image at 500dpi and the threshold is set at 450dpi any image will be resampled to the 300 dpi etc.

    To avoid this you can turn off the downsampling altogether, or set the downsampling settings to 1200dpi / 1400dpi. There are seperate settings for colour, monchrome and greyscale. If best quality is an issue then you may also need to set compression to none, or set to maxium quality. Otherwise you may still get jpeg artifacts creep in.

    Typically 1200dpi resolutions are only really applicable to raster black and white images / line work. which you would be running on an imagesetter. I can't think of any reason to make a colour image that size, I don't think there are any printers that have a screening resolution enough to make use of that data, and even if it did it would be well beyond the resolution of the human eye anyway?

    Even if you take the same image and enlarge it for large format/ billboard the screen and resolution are really pretty low...

    Its just going to make huge file for huge sake....

    Hope that helps, are your illustrations black and white pen ?
    purelimejuice likes this.
  5. @GCarlD

    @GCarlD Well-Known Member

    Yes there are very good points made there by Andy C. Even if it was to be billboard size it would actually be lower res, as it is viewed from a distance so there is no need to be high res. For the life of me I cannot fathom why they would need your images at 1200dpi, especially seeing as they are illustrations. The huge file sizes that each image is going to make, is just going to cause an unnecessary headache.
    purelimejuice likes this.
  6. purelimejuice

    purelimejuice New Member

    Thank you!

    Hi Andy C and CLHB, thanks so much for all your help - I have now resupplied the files by changing the compression figures as suggested and I'll see if that works- the problem with being so inexperienced is that I don't know what I don't know so this was all so much stabbing in the dark for me. I need to get to grips with all of this properly, will keep you posted! :icon_smile:
  7. Guys - it's PPI. Printers output dots. Files contain pixels. That's not just pedantry on my part (ok it is a bit) but think about it... dots are round. Pixels are square. Dots from printers are normally one of four colours (sometimes more I know, but basically, the same number of colours as there are inks in the machine) Pixels on the other hand are any of up to 16.7m colours. The resolution of your file has NOTHING to do with the number of dots that a printer produces. ppi and dpi have NO relationship with each other.

    A printer asking for a final size file at 1200ppi is crazy. On a machine printing a 9pl drop, you'll get a dot of between 50-60 microns. I don't believe you'll see a visible difference in quality between an input file of 200ppi or 300ppi in most circumstances. Some say they can but they've never been able to when I've tested. I'm not aware of any circumstance where you need to go beyond 300ppi!

    EXCEPT - my guess is that they ask for artwork at 1200ppi when working at 25% scale.

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