Reducing the JPG sizes (in MB) is making my exported PDF a larger (?!) file instead of smaller.

[danya31127621orfu]

I'm having an issue where I'm trying to reduce the size of my PDF portfolio (from 10MB - 5MB) by reducing the file size of each of the JPGs in the InDesign file. I'm not changing anything else, just the file sizes of the JPGs, so logically my expectation was that when I exported the edited InDesign file to get my new PDF portfolio I would have a portfolio that had reduced in MB size. Instead, the new PDF is more MB than the one I had with larger JPG files in it. It makes no sense. Again, the compression settings when exporting have not changed, I've made sure all the links are connected to one folder. I'm at a loss. 

[Steve Werner]

What PDF settings are you using when exporting from InDesign? What PDF Preset? What Compression settings?

Those would be the factors which would have the greatest effect.

Why are you concerned about reducing the size of the PDF portfolio? With inexpensive hard drives and cloud services, the size of PDF usually doesn't matter.

[danya31127621orfu]

I need the PDF for job applications and they often request either 10MB or 5MB sized portfolios to be attached. In terms of the compression settings, they are unchanged. I'm literally copying the InDesign file I use for my 10MB portfolio then only changing the size of the JPEGs linked into the file - changing them to a smaller MB size, which in theory should make the export smaller, but it isn't. It's currently making it larger. So currently My InDesign file with smaller JPEGs is exporting as a larger file than my InDesign file with larger JPEGs, despite the export settings being exactly the same. 

[rob day]

Here’s a file format compression example. This page has a 233MB, multi-layered, .psd file placed. If I Export to the default PDF/X-4 preset—Maximum Quality JPEG—the exported PDF is 1.5MB:

If I place the same file as a high quality .JPEG (16MB), the exported PDF is also 1.5MB:

[rob day]

Hi @danya31127621orfu , the file format of the placed images has little affect on a PDF’s Compression. When you place a JPEG it gets decompressed and the image pixels get recompressed based on the Export>Compression settings. That’s why in general the JPEG format has no advantages as an image format and plenty of disadvantages—double Compression on Export being one.