[HELP] PDF Compression Quality

[Pappy]

I have a few questions about the different compression qualities when saving files to PDF.
Recently I've been designing tabloid sized posters for clients with the aim of having them printed at a digital printshop. I do the bulk of the work in photoshop at 300dpi, then place the file within illustrator and save as a PDF with bleed and cropmarks without any compression. Sometimes these files are well over 50mb, which I then upload to an online file storage site and send the client the link who then takes it to a printer.

When it comes to digital printing, could I compress the files using of the built in compression modes (ZIP, JPEG or JPEG2000) without substantially compromising the quality of the arrk?

I've tested the different compression modes and the image quality options within them and have found that I can greatly reduce the file size and still have arrk that looks great at 100% or more. But will it print as crisp as an uncompressed file?
Also, I'm not sure what the exact differences are between ZIP, JPEG and JPEG2000.
I'm curious to hear what designers and printers would recommend when it comes to sending or receiving print-ready arrk.

[Typolover]

Zip is lossless and produces the biggest files.
Jpeg is lossy within 8x8-pixel-blocks.
Jpeg2000 is lossy all over the image.

You are the only to decide if quality is good enough To check, scale everything down to 300 dpi (but keep vectors).

What you now see on your screen is equivalent to Zip-compression.
Now save the image as JPEG and as JPEG2000.
What you see, when you open those images, is equivalent to JPEG and JPEG2000 compression.

For photos and other "real world sources", JPEG and JPEG2000 are fine in my opinion. As long as the sharp edges are still in vector format, both compression formats do not hurt visual image quality. The 8x8-pixel-blocks of JPEG are pretty small when printed in 300 dpi, so even slightly bad JPEG-compression should still look fine.

If you can's see any error at 100% on screen, you have no chance to see it in 300dpi print because pixels are smaller and the ink will smear at least a little bit.

[Pappy]

Thanks, that's what I was thinking. If I can't see any artifacts or pixelating at 100% then the file should be fine. But then I think that's just foolish thinking on my part because there must be many other factors to consider.
Ultimately I was just being lazy and wanted to see if I could compress the file to 10mb so it would fit as a standard email attachment. But I feel like I really shouldn't compromise the quality of the arrk for that reason al.

[salvatore]

I wouldn't compress it with anything other than zip. https://www.wetransfer.com/ is just as good as an email attachment, and you can send files up to 2gb.

[vasilescu]

JPEG2000 and ZIP lossless compressions should make no diference in image quality.

JPEG2000 with compression + JPEG (which is compression-only, lossy) make a slighter or more difference. Basically, if you save it as a high quality JPEG (90% or more quality), you will have a slightly (or barely visible) smaller quality, and a significative filesize decrease.

So, you decide whether you really need lossy compression. It's best not to need it.

[Mind_War]

But it's safe using jpg imagens in a layout inside indesign for exemple? Isn't better use tiff for exemple?

[adsfigo]

indesign and place the image in layout, save as pdf.

Acrobat Distiller - open your pdf file in acrobat save as a .ps file. Close Acrobat and open distiller, drop .ps file in.