PDF to image - Maximum dimensions seem to be 842*842 ?

I have recently started working with CQ5.6.1 - hot fix 1.

I have been creating a slideshow component for a customer:

- The slides for the customers slideshow must is composed of images.

- The source for the slideshow is a pdf.

We have set up a 2 process step workflow - The workflow is used on a pdf in the DAM:

1, Create sub assets

2, Run another workflow on each "Original" subasset path. (fx page 19:  /content/dam/ProductName/cq5_howto_website.pdf/subassets/page19.pdf)

The second workflow does the following:

1, Create web enabled image with arguments: dimension:1200:800,quality:100,mimetype:image/jpeg

2, Create web enabled image with arguments: dimension:1920:1200,quality:100,mimetype:image/jpeg

The results look as I would expect, at least the rendition names, fx page 19:

/content/dam/ProductName/cq5_howto_website.pdf/subassets/page19.pdf/jcr:content/renditions/cq5dam.web.1200.800.jpeg

content/dam/ProductName/cq5_howto_website.pdf/subassets/page19.pdf/jcr:content/renditions/cq5dam.web.1920.1200.jpeg

The problem is that if I view the image for: content/dam/ProductName/cq5_howto_website.pdf/subassets/page19.pdf/jcr:content/renditions/cq5dam.web.1920.1200.jpeg, then its dimensions are 595 x 842 - This is far less then I expected. The ratio is fine btw. I did however except the dimensions to be bigger.

842 px seem to be some kind of magical limit?

I have checked the "Original" aka /content/dam/ProductName/cq5_howto_website.pdf/subassets/page19.pdf it is a full pdf page that looks just fine (AKA, it contains text that I can copy, opens in a pdf viewer…).

I have also checked that "Day CQ DAM Buffered Image Cache", it has 2000*2000 set.

Any help would be appreciated.