Images in PDFs are too dark - wrong color, brightness, contrast

Question

Images in PDFs are too dark - wrong color, brightness, contrast

I use my IPAD mainly for viewing medical books, e.g. radiological atlases. Most come in PDF format and most don't look much different on the IPAD than they do on PC. But it is very frustrating to find that the most important book I need looks incredibly bad on the IPAD - it's color reproduction of images is very poor compared to the PC. I've tried all possible viewers, the problem must be in the PDF rendering engine of the IPAD.

Is this problem already known and is there a solution?

Thank you for your help.

IPAD 32GB 3G, iOS 4

Posted on Jan 6, 2011 6:35 PM

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Answer 1

Jan 15, 2011 1:35 PM in response to Medical PDF fan

I know this is an old post, but I've been working on several large PDF projects for IOS devices recently.

The short answer is that the iPad has specific PDF image rendering requirements.

It has to do with the way the PDFs are encoded. For example, the iPad PDF reader does not support JPEG2000 color image compression performed by some PDF encoders. You'll see this as images simply missing on the iPad.

And depending on how the images were prepared (sRGB vs CMYK, etc) and the compression settings in the software used to create the PDF, colors may appear inverted, blues may appear red, images may be too dark, too light, cut in half, etc. It's is a complicated subject.

Right now I know of no workaround on the iPad. The PDF itself needs to be redone.

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Answer 2

bebelitz

Level 1

0 points

Jan 28, 2016 9:05 AM in response to Sb001

Hello,

I just made a portfolio and found that if I changed the settings in the Output field I was able to view the correct color when using Dropbox to load my files into iBooks on an iPad!

Convert to Destination

choose "Apple RGB"

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Answer 3

Jan 6, 2011 7:06 PM in response to Medical PDF fan

Medical PDF fan wrote:
. . . .Most come in PDF format and most don't look much different on the IPAD than they do on PC. But . . . the most important book I need looks incredibly bad on the IPAD - . . .

You seem to be saying that most of the problems actually revolve around a single book. Despite your rush to judgement, the problem is just as likely to be the result of something in the file itself, or in the app you were using to view it with, and have little if anything to do with the "rendering engine".

Is this problem already known and is there a solution?

Well, if it manifests in a European medical atlas then it's unlikely to be a widely-known problem across most of the user base. It xertainlymis notmbeing widely discussed here. Whether or not Apple might know about it, or something related to it, is unknown and would never come to light in these user-user forums. For that matter, if this is the only place that you've brought this up then Apple still does not know about it; these forums are not used for that purpose.

Thank you for your help.

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Answer 4

Jan 7, 2011 6:39 PM in response to Michael Morgan1

No, it's not just one book. I found others too, but they are not as important.

I searched google for a solution and found other people have the same problem, but none has a solution:

http://forums.macrumors.com/archive/index.php/t-890057.html

How do I make Apple aware of this problem? 🙂

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Answer 5

Jun 26, 2011 3:39 PM in response to Medical PDF fan

I'm having the same problem with a bunch of pdf documents that I created by "printing" from web pages to pdf documents using a product called Scansoft PDF Creator. They look absolutely fine on my Windows PC when viewed with Adobe Reader X, but when I view them on my iPad 2 all of the photos are rendered with reversed colors. Green is purple, etc.

How the heck can this *not* be considered a bug in the iPad pdf engine, and why is it not an easy fix? The pictures are there and they look fine except that the colors are all reversed. When I do a Google search there are a lot of folks experiencing this problem with a lof of different pdf documents from many different sources for many months. I don't understand why Apple hasn't fixed this yet.

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Answer 6

Sb001

Level 1

0 points

Oct 17, 2011 3:44 PM in response to hansjoergfromlindau

I am a designer and got an iPad2 as a present so that I can always have my portfolio with me, because the iPad is the best portfolio case, right? Well guess what: my PDF portfolio has the same problem described in this discussion. The problem is not on all pages but on most of them and I have made the document with inDesign. I thought to forget the PDF and use the webpage ISSUU that I normally use to show my portfolio if I do not have my laptop, and guess what, it needs Flash player. I am so frustrated! For me Apple is responsible for this and I am very, very, disappointed. Shame!

By the way, as designer I need to sketch, and sketching with an iPad is also useless, and so is typing with a 3 layered k boards missing navigations tabs.

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Answer 7

Nov 21, 2011 1:41 PM in response to Medical PDF fan

Same problem here! I bought the iPad2 mainly to read PDF's about photography and the issue about pictures coming up too dark is very annoying to say the least. This should be resolved at the iPad end and not in the pdf files since the problem is that it "reads" the colorprofile of the embedded pictures wrong or not at all. The suggestion to redo the pdf-files is very impractical.

Lots of people are having this problem. Apple wake up please and fix this for your users!!

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Answer 8

Nov 24, 2011 10:31 AM in response to Roland Vermeer

Hi, did anybody read my fix to the problem from 19.09.2011?

Here is another one I found on ipadforums.net:

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.

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Answer 9

Nov 24, 2011 10:53 AM in response to hansjoergfromlindau

Nice but i'm not a Mac owner.

Your suggested fix in the 19-09 post is not clear to me. Using version 9 of Acrobat Reader there's no "save as..." only "save a copy" and that doesn't give any options to change to Mac RGB. Are you using a Pro version of the reader?

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Answer 10

Nov 25, 2011 3:32 AM in response to Roland Vermeer

I used Acrobat, not Acrobat reader!

I changed to Apple RGB in the settings and than saved the file.

But the mess is, that after upgrade to iOS 5.0.1 I have again dark images.

It is of course an Apple problem, but only for those few which read professional pdf-books.

Apple don´t care about the few, that´s their policy!

I am waiting for the first Win8-pad, not for gamers, but for serious users <-((

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Answer 11

Dec 7, 2011 7:43 AM in response to hansjoergfromlindau

In the meantimee I asked Goodreader´s support and they confirmed that it is the Apple rendering engine causing that problem.

I finally found a fix for my radiological images.

I opened the book in Adobe Reader X and printed it with Adobe pdf into a new pdf-file using black&white under paper quality and activated the first 3 elements under advanced/colourmanagement. All the dark cmyk-images are no longer dark, but still brownisch (don't know why, but acceptable).

Others should maybe try other settings. Good luck.

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Answer 12

Apr 12, 2012 6:11 PM in response to hansjoergfromlindau

I'm not sure if I'm having the same problem but pdf's display very dark in ibooks. If I open the exact same pdf in acrobat (ipad version) everything looks fine. It's definitely an apple issue and should be fixed.

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Answer 13

May 9, 2012 2:36 AM in response to Medical PDF fan

This issue is coming from PC's color profile. I believe all the PDF you read were produced from a PC machine.

One possible solution is (required Adobe Acrobat):

-Open in Acrobat

-Look for "Preflight" option

-Convert to sRGB.

This should solve the PDF issue.

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Answer 14

SLebrun

Level 1

0 points

May 9, 2012 7:13 AM in response to Medical PDF fan

To agree with folks like Ripper2020; PDFs that are unreadable in iBooks due to, for example, background images washing out the text render perfectly in Adobe Reader for iPad. As in, copy the file out of the iTunes library to Dropbox, go to iPad, open Dropbox, sync, and click 'open in Acrobat Reader.' This is an iBooks issue, and most definitely qualifies as a bug.

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Answer 15

jfobrien

Level 1

0 points

Sep 22, 2012 10:02 PM in response to Medical PDF fan

Ok so don't know if it will help all out there but I just solved a similar problem I was having with inDesign layouts I had exported for my portfolio that were appearing really dark and unviewable on my iPad (3rd Gen). It seems that all I had to do was to change the export settings to not embed the RGB colour profile. Again not sure if it will help all but it helped me and frankly it makes sense given how Apple products tend to use very different colour profiles to Windows based PCs.

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