Downsampling images when they are produced, or in the final document?

Question

I work with documents mixing text and bitmap images, for which the final format is a PDF file. Most of the times, I produce my own graphics, which means that I have a choice of:

1. Creating all bitmap images at very high resolution, embed it in the document, and post-process the final PDF document to downsample all images to my target resolution (say, 300 dpi).

2. When I create the bitmap images, export them at a size consistent with the target resolution and intended size, then include them in the document (and no need for downsampling later on).

The second option has one major downside: it means that if I change my mind later (e.g., I want to include an image at twice the original size), I have to recreate the bitmap image file. It's not a very big deal, but still. Because, I cannot see any downside to the first option, that's what I regularly use.

My question is: how do you arbitrate between these two options? Do you always work with overly high resolution images, and downsample everything as the last step?

Answer 1

It sounds like you already have the answer: stick with option 1, which offers you a good amount of flexibility, and probably saves you time in the long run.

However, in my experience, there have been times when I preferred to resize the images and place the correctly sized image in my document. This has usually been either because:

1. I wasn't happy with the downsampling results (I've had problems sometimes with programs like LibreOffice not producing very crisp low-resolution images for producing PDFs to display online or send by email).
2. I was trying to squeeze the file size down as low as possible while maintaining a given resolution; working with good photo editing software (eg Gimp or Photoshop) would allow me to preview my images while I adjusted different quality parameters.

Thus, what I usually do is have all my images in a subfolder in my project directory and then, if fine tuning is required, I create a copy of that folder (in case I ever need to revert to an earlier version) and I modify the source images as required.

But, as mentioned in my opening line, for most purposes, sticking with option 1 is probably sufficient; after proofing your PDF, you can decide if it is better to optimize your images prior to placing them.