Dealing With Very Large PDF(s)

I have a flight manual .pdf I use for work that is just under 3,000 pages and 800 mb. It contains highlights and a few notes. It loads correctly on DT and DTTG but when making edits on my Macbook Pro they do not seem to be syncing with DTTG and are also resulting in the “beachball” running for several minutes (worst case scenario). No other syncing issues with any files that I am aware of. Is there anything I can do to improve file performance in this case? I was considering using PDF compression…?

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Give it a try. The best compression will be on the images. I have my PDF Pen compression set to reduce to 150 dpi if greater than that. Going down any more seems to affect the readability.

Edit: Also, you don’t mention how you are synching. Bonjour probably the quickest and most reliable.

PDF Compression may actually make the problem worse. Compression does not permanently reduce the size of a file. It does exactly what it says: it compresses it. What follows a compression? A decompression. In order to access compressed resources, they have to be decompressed. Decompression can also be slow.

When the application is stalled, do a Spotlight search for Activity Monitor . Select our application in the list of processes - it should show “(Not Responding)” and the name in red - and press Command-Option-S to run a sample on it. When the sample window opens, press the Save button and save it to your Desktop. Please attach this text file to a support ticket so we can inspect it. Thanks!

Would appreciate if you could elaborate. When I use PDF Pen to do what they call “optimise” and say I reduce all images to say 75 dpi more often than not those images in the new file are unreadable. The files are often drastically smaller which is my goal. But I have settled on 150 dpi to get good file size reduction but acceptable image quality for my file archive.

Even when opening the new file in Preview or DEVONthink PDF viewer the images are unreadable if 75 dpi used. I always concluded that was a permanent compression that is not undone by any subsequent process to “decompress”. If there is a decompress as you say would not the images be like they were before the optimisation (compression)?

Is nomenclature the issue? Is Compression different than PDF Pen Optimisation?

Yes, file reduction such as downsampling images us vastly different than compression. Downsampling is removing data. Compression is analyzing and storing in a manner that takes less space to store. It’s likely more tightly packing something. But when you open it, the contents have to be unpacked. There are several compression algorithms for PDFs, some more aggressive / efficient than others.

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So yes, I downsample and as it is for documents for reading and not for publication works fine for me to keep huge PDFs smaller.

Another solution to dramatically reduce a PDF size is use Abbyy MRC compression, that more than “compression” is “vectorization”. What it does is take the parts of the images recognized as text and vectorize that part, making it crisper (and corner escalated, but not much). Personally, I like it more than normal graphic compression or down sample because text remains crisper and easy to read.

And yes, in this case, the de-compression takes a lot of time and power, and it is appreciated in old iThinks and sometimes in Mac. The advantage here is that the process is only used to visualice the PDF, and the annotations go as normal at the end of the file. In my one-generation old iThings, the opening of one of those MRC-compressed documents is not appreciable except if you scroll fast, that you must wait one or two seconds to show the text in the page shown.

However, there is a second handicap: this option is only available in Abbyy paid versions, and macOS version performs a lot of worse than Windows one (worse in speed and in compression factor). Normally, in Windows, a 200 MB text scanned PDF is converted in 20 MB or sometimes less if you blank the background. As a sample, my last scanned book (“For us, the living”, Heinlein, from Virginia Edition) scanned images are 250 MB size, but the final not-background-whitened PDF generated is 16 MB with covers at full resolution.

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