zip vs jpeg high quality

[drwin]

I want to print as PDF, and upload (to a print-on-demand publisher) a long word document with dozens of photos in it. The images are NOT embedded or inserted, they are linked to file, so that the images have the same ppi as the original files (300ppi). I have done this several times, using dopdf and selecting the "smaller file" option (which results in a 58MB file). (The dopdf "higher quality image" option yields a 97MB file which takes a long time to upload.)
The 58MB files have always been accepted by the publisher, with all images retaining the original 300ppi. However, after making some editorial changes and re-submitting, the publisher now tells me that the images that were previously 300ppi have gone from 300ppi to as low as 170ppi. I did not change any of the images. I did add some images. My questions:
1. It is my understanding that the "smaller file" option creates a zip file, while the "higher quality image" option creates a jpeg file. Is this true?
2. Since previous files with fewer (up to 70) images have always retained their original 300ppi, and the drastic, across-the-board reduction in ppi occurred for the first time after adding a few (4) images, there seems to be a cutoff point beyond which the "smaller file" option begins to degrade the images. Is this true?
3. Any insights as to what would cause this sudden change would be most appreciated.
Misc: Running Win7, Word 2007; image ppi as per Photoshop on my end and whatever the publisher is running on their end.

[Claudiu (Softland)]

Hello,
1. This is in fact the other way around. The ZIP method compresses the file less but keeps the quality of the image, as the jpg method actually processes the image as well besides compressing it more than the ZIP method. So this is the other way around as you have explained it.
2. We cannot predict how the image will be processed by the jpeg procedure besides compressing it to save file size unfortunately. You will have to mix and match to see which method suits best for your needs.
Thank you.

[drwin]

Thank you for a quick response. I'm still a bit confused. I based my comments on the following:

............

http://dopdf-printer.software.informer.com/

What's new in version 7.2

It contains one important feature, now on the Save As dialog you will be able to select between a "Small file" and a "High quality images" filter. Each of these filters uses basically a different compression engine for the documents:

- Normal ZIP compression for the Small file filter

- High JPEG compression for the High quality images filter

By default the "Small file" filter will be selected, but if you're not happy with the quality of the images in the resulting PDF, then you should use the other filter (which increases the size of the resulting PDF).

...........

Based on what you've posted, the above information from "software.informer.com", which I obtained online is totally incorrect. Just want to make sure that this is the case.

Thanks

DR

[Claudiu (Softland)]

Hello,
The information on the Software Informer website is not correct unfortunately. What we have explained in our previous reply is the correct handling for the image compression.
Thank you.

[drwin]

Thanks! I was going to contact software informer and let them know, but I would have to register and all that and I'm afraid I was too lazy.

DR