/drive/community?hl=en
/drive/community?hl=en
11/17/13
Original Poster
I-Chen Tsai

Google Drive PDF viewer is so bad in displaying color

This file:
https://dl.dropboxusercontent.com/u/14573548/CVCT2014_Flyer_RGB.pdf
 
If I upload it to Google Drive, then view it on the browser. The color scale is downgraded so much, as attached figure.
It seems Google Drive PDF viewer can't handle color well. Please fix it.
 
Chrome PDF viewer works fine. Maybe Google can use it in Google Drive.
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All Replies (10)
Google user
11/17/13
Google user
Hi,

I agree - I shall pass this on.

- Mike
Darren Tay
11/22/13
Darren Tay
I have this problem too.
One curious thing is that the colors display correctly for the first 2 seconds or so, then it switches to the low-colors view.
Bas Braams
12/1/13
Bas Braams
I-Chen Tsai's example is excellent and there are a few other early examples of this color rendering issue; for example by Turkeyphant here [1] and on Stackoverflow [2], by Mike Brantjes here [3] and by glockofpatience here [4]. Brett Morrison has an excellent example under [5], but I believe that it is a direct view through the Docs pdf viewer so what is seen there may change over time. I have contributed various examples under those conversations too and among those the one that shows the problem most starkly is the simple RGB color test cube; see under [1] or [3].

I try to recognize just what is going on; what color palette is being used in the Docs PDF previewer. I don't know it, but there is a helpful Wikipedia article on color palettes [6] and I followed their example, which uses an image of a parrot and an image of an array of colors. I inserted those images into an empty Docs text document, downloaded (exported) that document with conversion to pdf, and uploaded the pdf to two locations: My Docs+Drive space [7] and my Dropbox space [8]. If I view [7] it is done through the Docs PDF viewer and if I view [8] it is done through the standard browser pdf viewer. (In the latter case it seems to make no difference whether I use Chrome or Firefox.)

The result is dramatic (as it is for the RGB color cube) as witness the two attachments.

My hope with this exercise is that I might identify exactly what algorithm would be used in the Docs PDF Viewer, simply by finding an exact match on that Wikipedia page [6]. However, I only find imperfect matches. The renditions there that to me look most like the Docs PDF Viewer rendition are the EGA for IBM-AT (1984) and the Atari ST (1985). Let's agree that these two were tops at the time, but maybe not ahead of their time by 25 years.

[1] (2013-05-22) Google Docs Viewer mangling colours on images

[2] (2013-05-20) Poor image rendering with Google Docs PDF viewer

[3] (2013-06-02) How to get color back in googledoc viewer ?

[4] (2013-10-15) horrible pdf image resolution - color blends striate

[5] (2013-07-11) .pdf views in distorted indexed color

[6] Wikipedia (2013-12-01) List of color palettes

[7] File GDocsTestColorPalette.pdf on Docs+Drive

[8] File GDocsTestColorPalette.pdf on Dropbox
John Sidles
12/24/13
John Sidles
Please add me to the list of unhappy Google Drive users in regard to bad-quality PDF reproduction.
 
Did anyone at Google *ever* test their PDF viewer?
 
It seems that every-time we attempt to share a professional-grad PDF document with colleagues, Google Drive finds some way to provide a bad experience.
LindseyB
1/24/14
LindseyB
This is a fairly major issue that I hope Google addresses soon. I run a chainmaille business and I have a Chromebook on which I use Google Drive's PDF viewer to follow color tutorials for learning new patterns. The color display is so terrible that it sometimes makes it almost impossible to follow the tutorials without a significant headache.
 
Please help, Google!
FabriceL
2/5/14
FabriceL
Same problem here...
 
What's weird is sometimes the document first opens with all the colors being nice and then it gets all ugly. What is the point? I could understand making it ugly for fast upload but it seems to do the opposite...
worldpoop
2/28/14
worldpoop
Significant quantization and mapping problem. The Google Drive PDF preview is not "safe" to deploy, unfortunately, so we are using another cloud service at the moment. (We have also found that "anyone with the link" has not been reliable -- inconsistently blocks our clients attempting to view, with an unnecessary sign-in request. Depends on browser often, but still not "safe". These are both roadblocks for us using Google Drive.)
 
Thank you.
worldpoop
2/28/14
worldpoop
The preview actually renders correctly(!) for a second or less, then seems to remap the image. Here, look at the QT movie. That is not a preview "compression" or "low resolution" problem.
 
Thank you!
Bas Braams
3/2/14
Bas Braams
<<Here, look at the QT movie>> Thank you, worldpoop, for that movie, which records what Darren Tay noted here on 2013-11-22. Very briefly the colors display correctly and then it switches to the low-colors view.

The example of the man holding the cat works quite well: in the intended original view the cat looks alive and in the Docs+Drive pdf viewer view it looks as if rigor mortis has set in, and the man himself is on his way out too.

We have figured out now (see some of the earlier cited postings) that the Docs+Drive pdf viewer uses 5 bits and no dithering. If the image is recognized as color then the 5 bits encode 32 colors, if it is recognized as grayscale then they encode 32 grays, and if it is diagnosed as a mix of color and grayscale then they encode 16 colors and 16 grays.

Could one do worse? Well, instead of using 5 bits the Docs+Drive team could have settled on 4 bits or fewer. However, a better way to make it worse is the following: use 5 bits and then invert the resulting binary number, switching a right-to-left and a left-to-right reading. That way a smooth gradation of color or grayscale gets coarsened first and then replaced by an oscillating pattern, and the image becomes completely unrecognizable. Indeed, as described under [1], it appears that the Docs+Drive team has implemented this technique for viewing Tiff images. The date on [2] and the reply there suggests that the problem has been around for some time.

I note that the Docs+Drive viewer seems to handle stand-alone *.png or *.jpg images fine. But when such an image is inserted into a pdf file then the colors get mangled.

[1] (2014-01-27) Re: Google Drive inverting color on picture previews

[2] (2011-06-20) .tiff files have inverted colors when previewed with google docs

worldpoop
3/2/14
worldpoop
Wow, good analysis. So, what is the purpose of 5-bit color, especially since the original image has already been rendered and visible for a second?
 
FYI: I discovered it is even worse. If you "OPEN" the preview to view supposedly the full PDF, the sickly color banding remains. (OR good image for a second, then turns to sickly image.) Basically, at least in my experience with the file that appears in the QT movie above, it is impossible to correctly view a pdf if it is rendered from Google (Drive).
 
So... do Google folks pay attention to these discussion? Is there a chance this maybe improved?
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