PDF thumbnail truncated, settings issue or bug?

[Art]

For A3 size PDFs iMatch 5 generates a thumbnail preview, but it does not show the full image of the A3 size, only approximately 60% of the width though it does show the full height correctly (297mm). The preview seems almost square.

Is this a settings issue (max size for previews is set to 1600x1200, so it could e.g. be a ratio issue even though it is almost 1.41 ratio) or a bug?

[Mario]

IMatch uses whatever PDF 'preview / thumbnail' is returned by the PDF WIC codec installed on your system. If you have no WIC codec, IMatch falls back to using the thumbnail support built into Windows. Windows itself then relies on whatever shall extension is installed to handle PDF files. Usually this is something installed by an Adobe product or third party PDF reader.

I have never heard about the problem you are describing. Problems with PDF thumbnails are not uncommon, because the Adobe shell extension is unreliably and breaks with many PDF files. But so far if it worked, it worked. I would need to see one of your PDF files to know more. And of course it may/will work differently on my machines. I have a WIC codec (FPV) on some installed, and on others a modern version of Acrobat Reader.

Did you try installing the latest version of Acrobat Reader and then Shift+Ctrl+F5 forcing an update of the problem file?

[Art]

Latest version of Acrobat Reader is installed, as well as FPV for generating thumbnails that Windows or other software cannot generate on their own. My main PDF editor is Bluebeam but there are some other programs that also can function as PDF viewer/editor/printer.

The "problematic" PDFs are vector PDF files, image PDF files do seem to work ok as I don't recall seeing truncated thumbnails of PDFs containing only an image. Could these PDFs being vector PDF files be a cause for the truncated thumbnails? Windows 10 does show a full preview in the preview pane.

I can't share the original "problem" PDFs but I'll create an example for testing and send that to you if it generates a truncated thumbnail, along with some more details on installed PDF editing/viewing software. If you would like specific details to be included just let me know.

[Mario]

I have seen many PDF files not producing any kind of preview with Acrobat or FPC PDF codec. Others in my collection crash the Acrobat shell extension, after it uses up 4 GB of RAM. But cropped PDF files are new. By all means, send me a sample. But I cannot do anything about this. IMatch does not include code that can extract previews from PDF files, I rely on the built-in support in Windows.

When I recently evaluated the market for 3rd party PDF components in march, the cheapest component would cost be about 1000US$ per year, plus several hundred dollars per year maintenance. This would allow me to extract PDF thumbnails myself or even generate thumbnails from any page. But there is no guarantee that the components work for all existing PDF files, and the costs are way too high.

Try to create your PDF files for the PDF/A standard, which is for archiving and the most compatible across all platforms and software products.

[Art]

Mario,

Thanks for the info, then at least I know it is not a settings/configuration issue that might solve this. I can understand you're not going to spend 1,000 USD plus hundreds per year if there is no real demand for PDF thumbails especially if it could very well be caused by something outside IMatch.

I've sent you an e-mail with test files and some more details regarding installed PDF software etc.
After sending the e-mail I realised I had forgotten to try printing to PDF/A1-b but that made no difference either.

For those also having this issue, given Mario's comment about Adobe Acrobat (Reader) and its issues, uninstalling Acrobat Reader and restarting the computer and then rebuilding the thumbnails made no difference. Not even for newly created PDFs, the thumbnails remained truncated in the horizontal direction.

[Mario]

Hi, Art

I've added your sample files to one of my databases (sorry for the delay, IMatch 2017 was prio #1 for the past two weeks).

I have FPC codecs installed and IMatch prefers an installed WIC PDF codec over the Windows "thumbnail" generation (because the component installed by Acrobat Reader  is buggy and often causes problems).

But the FPV codec are unable to produce thumbnails for any of your PDF files.
I checked each file with Help > Support > WIC diagnosis. So this makes these PDF files 'special'.

IMatch hence falls back to using the native Windows "Extract Thumbnail" function, which internally uses whatever shell extension is installed that supports PDF files.

Please see below what I get (click to zoom).



This looks OK to me. Maybe it helps just to re-install the latest Acrobat Reader. Adobe software sometimes works in mysterious ways and a re-install may fix the issues.

Then do a forced update of the problem files: Select them in a File Window, then press <Shift>+<Ctrl>+<F5> and in that dialog choose "Force Update".

[Menace]

FPC creates on my computer bad tumbnails (just one image, which was inside the document; often wrong colors). That's why I installed FPC again, but uncheck pdf-Files.

[Art]

FPC creates on my computer bad tumbnails (just one image, which was inside the document; often wrong colors). That's why I installed FPC again, but uncheck pdf-Files.

You can also from the control panel>programs etc.  change the installation and uncheck the PDF-files there, it would save the uninstalling and then reinstalling part. I've also deactivated the PDF preview for FPC, which does help.

[Mario]

At least for the images in this test. FPV did not return a thumbnail/preview anyway.

[Art]

Hi Mario,

[...]
I have FPC codecs installed and IMatch prefers an installed WIC PDF codec over the Windows "thumbnail" generation (because the component installed by Acrobat Reader  is buggy and often causes problems).

But the FPV codec are unable to produce thumbnails for any of your PDF files.
I checked each file with Help > Support > WIC diagnosis. So this makes these PDF files 'special'.

IMatch hence falls back to using the native Windows "Extract Thumbnail" function, which internally uses whatever shell extension is installed that supports PDF files.

[...]
Maybe it helps just to re-install the latest Acrobat Reader. Adobe software sometimes works in mysterious ways and a re-install may fix the issues.

Then do a forced update of the problem files: Select them in a File Window, then press <Shift>+<Ctrl>+<F5> and in that dialog choose "Force Update".

As mentioned in this topic https://www.photools.com/community/index.php?topic=6035.0 I have activated the enable preview in Acrobat Reader DC, made it the default viewer and force updated a batch of PDFs. This mostly solves the issue.

As to the PDF files being special, somehow I did get previews, portrait oriented PDFs gave a proper preview whereas landscape oriented ones had the truncated previews/thumbnails. This may have to do with the FPC codec having issues. The strange thing was that it happened with most PDFs. Now this issue might be aggravated by some of my programs also being able to function as PDF viewers and editors, two being PDF only applications (Bluebeam and Acrobat Reader) and others having this bolted on PDF viewing/editing functionality, so I can't exclude the possibility of some conflict in the background that interferes with thumbnail generation as opening the PDF might affect the thumbnail previews if the PDF gets opened in an editing program (PDF only or otherwise).

The acrobat reader DC with preview enabled as default viewer works for now for 98% of the PDFs to get a preview/thumbnail in IMatch, with the occasional PDF file behaving a little bit different, so for now I consider my main issue regarding PDF thumbnails within IMatch solved. (as long as I leave the PDF file option in FPC disabled).

Thanks for taking a look at the sample files and getting back on this.