The quality of linked images in JPEG and PNG exports has always been problematic. I think you'll see that InDesign objects don't pixelate–the problem is only with placed objects. The solution is to export as a PDF, open in Photoshop, and save as PNG or JPEG there.
See this thread. #16 has an AppleScript for exports to JPEG via PDF.
Thanks for getting back so quickly with an answer. I've glanced through the thread and agree it's likely the same issue. It's strange though that no one else seems to be calling out that there's a pixel limit or what that limit is.
Do you have any idea just why the limit is in place and why it's set at such a specific pixel volume?
Thanks for the script – I've given it a go and it's an amazing workaround – kudos (assuming you wrote it?) While I'd be happy to export to export using a script like this, the one you've provided isn't quite going to work for me unfortunately. First it only allows single page exports – I'm designing sites with dozens of pages and states, each of which need to be exported individually with this script.
Second, it doesn't allow PNG exports, which I'd prefer in order to avoid all those JPG artifacts that can creep in.
It seems a huge shame that you/someone has to take time out to build a script as a workaround for something that seems more like a bug on Adobe's part.
Thanks so much for your help on this.
I'm designing sites with dozens of pages and states, each of which need to be exported individually with this script.
Are the PNGs you are exporting going directly to the server or are you assembling the states in Photoshop? If the latter you can export the entire document to PDF and place the pages in Photoshop layers.
Not sure if this answers your question, but my current workflow is to export the whole document as separate PNGs into a local folder, then drag those flat PNGs into InVision to create an interactive prototype.
AcrobatProDC has a Image Export that would let you export all of a document's pages to PNG. I haven't checked the quality, but you could export your entire document to PDF/X-4 and try it out. The tool icon gives you some export controls including resolution. so if you wanted 4000x2000 pixel PNGs, set your ID document up to 4000x2000 pixels and export as 72ppi: