PDF images quality rendering : not the same on iPad and on Desktop Screens ?

Discussion in 'iPad General Discussions' started by davidch, Feb 24, 2011.

  1. davidch
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    davidch iPF Noob

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    Dear All,

    I have an issue i cannot seem to understand :

    A PDF rendered from indesign with high quality images does (really) not display the same on iPad than on Desktop monitors (apple 27'', LG 24'' or standard lcd 19'').

    You can find a test here : db.tt/J8oNwC1 (1.9Mb)

    Check these pages both on your pad and your monitor, and you'll find the contrast is much higher, the image much darker on the pad.

    Obviously when color, tone, contrast and light is of importance, this is a real issue.

    Could anyone advise me on a specific way to prepare the document from Indesign to get a high end rendering ?

    Export was done in RVB 150Dpi following usual scheme.

    Thanks a lot !
    Best regards
    david
    Last edited: Feb 24, 2011
  2. twerppoet
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    twerppoet iPad Legend

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    There are several PDF rendering engines, and the quality you get varies from program to program. Obviously the iPad doesn't have the same horse power to put behind it's PDF rendering as desktop or even laptop. So, the PDF rending engine build in isn't going to handle really large high quality PDF files.

    Given the nature of the device it is never going to substitute for a full computer for image rendering or or manipulation, at least not on a professional level.

    That said, GoodReader is probably one of the better PDF viewers on the iPad. It uses the iPad's included PDF engine by default, but does have it's own that can be turned on in it's settings. The other engine is supposed to be faster, not necessarily better quality, but you could give it a try anyway. GoodReader is a handy app to have around for a variety of reasons, so you'll likely find other uses for it.

    BTW, your file link isn't linking. You'll have to make two more posts before the forum will allow you to make links or attachments.
  3. davidch
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    davidch iPF Noob

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    Hi Twerppoet,

    Thanks for your message. I opened my test pdf (db.tt/J8oNwC1) with GoodReader. No luck, display is still as saturated/dark (tested with *Faster Engine* On and Off, same result).

    I don't have the impression the issue is with the *large PDF file*, but rather with the way iPad is rendering an image. My test PDF on db.tt/J8oNwC1 is less than 2Mb so that cant be so heavy.

    Do you have any idea who could give me more insights ? maybe i could export the PDF from the native document in a different way so that color balance then matches ?

    i'm really surprised by the difference in display, had never noticed that ! it's quite interesting :)

    Thanks for any input
    david

    ps/ yes, i'll look forward to posting more and getting my links linking ;)
  4. twerppoet
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    twerppoet iPad Legend

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    It it just the embedded images that are dark then?

    Check the color profiles for the images, before you import them and after. I'm guessing that Adobe RGB would be the most compatible, but it wouldn't hurt to experiment with a few others, including the iMac profile.

    Also, check the display settings on you iMac. It could just be that your monitor is displaying the pictures brighter than normal, and causing you to adjust the images in the wrong direction. You can run the display through a quick calibration using System Preferences. I don't believe this is the problem, but it is easy to check.

    Of course, if you use something like Indesign a lot, you're probably more familiar with monitor settings and color profiles than I am.

    I don't have Indesign to play with, so there's really not much I can do except make guesses.
  5. davidch
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    davidch iPF Noob

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    Hi,

    Yes, it is just the images that are darker.

    I tested upload and display of ''test.pdf'' on Issuu.com and then the colors are correct !! : ( url is issuu.com/kbsd/docs/testpdf ) :

    - test.pdf displayed on monitors (imac, pc) : normal colors
    - test.pdf on ipad (direct read, readdle, goodreader) : darker
    - test.pdf read on ipad through issuu.com upload : normal colors !!

    So there is a way for my iPad to read the same color info as my monitors, it's a question of knowing how to convert the pdf i suppose !

    i think i'll post the link to this forum to Readdle, GoodReader and Issu and see who can help ;)

    d.
  6. twerppoet
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    twerppoet iPad Legend

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    Thats a good plan. I'm out of my depth on this one.
  7. Rogerious
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    Rogerious iPF Noob

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    I have a couple of PDF books, both are on photography and the images are rather dark as well. I initially was using iBooks, then when I saw that the images were dark I thought it was the app. So after much searching and reading reviews I decided on Good Reader and the images were still dark. I played around with the light settings on the iPad and that didn't help much.

    I am a bit dissappointed with this as I was hoping to be able to read these ebooks without printing them out bit by bit as needed.

    So David let me know if you find a solution. I'm almost tempted to buy the Nook and see what that looks like.
  8. davidch
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    davidch iPF Noob

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    Hi,

    Sorry, i didnt find any solution, and we're therefore still working with darkened images.

    I suppose the next step would be playing with the actual native document, in this case InDesign with Tiff images, and modify the levels of the exported PDF, so as to get a correct rendering in iPad specifically. Didnt get up to that yet...

    If you see anything, dont hesitate to let me know :)
    david @ KBSD Digital Marketing > Agence Internet, Referencement & Communication Interactive > Agence Internet KBSD Digital Marketing a Geneve Paris & Kiev
  9. msparks13
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    msparks13 iPF Noob

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    Fix to PDF Image problem

    Little after the fact, but in case any one googles to this like I did, I did find a work around for this. Only on a mac...

    I am running Lion and I simple Save as in Preview didn't do the trick for me.
    Two options, One a little easier then the other.

    1. Open the file in preview. Chose File-> Export. Set the obvious and then under quartz filter select reduce file size. Then hit save. Put the file on your iPad and you should be good to go. This will also circumvent and "large" file size issues you may get from other ways to "fix" this.

    2. If you need to have the images in even higher quality, as the first option may decrease the quality slightly then there are more steps.
    Select the file you need and choose open with-> ColorSync Utility. Top left of the screen is the button to open filter inspector (three circles, one green, blue and red). Click the downward triangle next to Reduce file size and select duplicate. Rename the copy to anything and then Press the downward triangle on this file. Select Add domains. Then Expand the field (triangle on the left of the name). Expand Image Expansion. Change the quality bar to max. Expand Domains and check PDF workflows. Close the filters box.
    On the bottom of the original screen that was opened there is a filter option. Select the file you just created and click apply. Then save the file and you are good to go with a higher quality.

    This will fix any color issues with pdf images on iPads. I had pdf images that the colors were off on, almost negative and this worked like a charm. Once its set up its very easy and quick for future pdf image problems.
  10. japanconman
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    japanconman iPF Noob

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    Hi there, if this coincides with the issue i faced last time, it must be the Color Profile Management issue.

    Short Story:
    I guess you must be using Windows machine. Try change the color profile to sRGB or Apple RGB for the file intended for iPad.

    Long story:
    Windows and Mac started out using different color profile in their OS. What it affected? Pretty much everything deal with the display. If you notice image that are processed in Windows machine will come out "under-exposure" in Mac machine. All of these is due to the color profile , i.e., the way they render the Colors to be displayed.

    In this case, iPad (obviously a Mac family device), uses the same color profile as a Mac machine. So problem occurs.

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