Apparently competing dpi settings

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1

Trying to figure out how PDF Creator sets its quality. There are three dpi inputs:
.#1. in printer properties, advanced, there’s a graphic print quality in dpi
.#2. in the profile under pdf compression there’s a resample setting for color/greyscale images to so many dpi
.#3. in the profile under pdf compression there’s resample setting for monochrome (i.e. black/white) images to so many dpi

Aren’t #2&#3 competing with #1? I find that #2&#3 nearly determine the PDF quality, but how #1 is set still has a small effect on file size. For example, when I made:
.#1 = 2400; #2 = 600; #3 = 1200 the resulting PDF was 67,750 KB
.#1 = 600; #2 = 600; #3 = 1200 the resulting PDF was 67,651 KB
.#1 = 300; #2 = 600; #3 = 1200 the resulting PDF was 67,600 KB

So what exactly does #1 do? What is its relation to #2&#3?

2

(Curious as a first time poster, whether there’s a better method of posting the text I want than adding dummy characters?)

3

Hi,

I think the setting in the printer properties sets the maximum DPI allowed in the document and the PDFCreator image settings are only used if they are set to a lower value than the setting in the printer, but will need to look at this in detail.
How much DPI does the original document have? There is no upscaling in PDFCreator.

Best regards,

Robin

4

Robin,
That can’t be what the dpi setting in the printer properties does. Look at the three experimental results I posted. If setting 300 dpi in printer properties limited the dpi to 300, then my 29 page .docx would not make a 67,600 KB .pdf. To make this even more obvious I made a fourth .pdf using that same 600,1200 profile after setting 72 dpi in printer properties:

.#1 = 72; #2 = 600; #3 = 1200 the resulting PDF was 67,094 KB.

(Using your “High Quality” profile gives practically the same results.)

The .docx file being printed consists of about 20 pages of text plus about 20 images, at various resolutions, totalling about 200 square inches. At 72 dpi, 200 square inches totals just over 1 million pixels. With no compression at all this requires just 3 MB. Your 67 MB .pdf isn’t encoding just 1 million pixels, nor does it look like 72 dpi.

So again: what exactly does the dpi setting in the advanced printer properties pane do? What is its relation to the settings in the PDFCreator profile?

Dennis