[solved] PNG to PDF with specific size and pixel density

[monpantalon]

Hi,

I have a PNG image with arbitrary physical dimension but 222 x 308 pixels, and would like to make it into a PDF with physical dimension 111 x 154 millimeters and >= 300dpi, with no smoothing, i.e. visible pixels.

I have tried running the command

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convert in.png -size 111x154 -units millimeter out.pdf

or also (with the obvious difference that a6 is not the exact size I want)

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convert in.png  -density 300 -resize 100% -page a6  out.pdf

but can't manage to find the right set of options to make imagemagick do what I want it to.
I admit getting lost in all the options imagemagick has.

I'd be thankful for any help on getting the right command for this task.

Thanks!


Imagemagick version is

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Version: ImageMagick 6.9.9-38 Q16 x86_64 2018-03-12

.

[snibgo]

111 x 154 millimeters and >= 300dpi

111/25.4*300 = 1311 pixels
154/25.4*300 = 1819 pixels
So resize to 1311x1819, set the density, and write the file.

with no smoothing, i.e. visible pixels.

I'm unsure what you want. Perhaps "-scale" instead of "-resize".

[monpantalon]

OK,

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    convert $i -scale 1311x1819 -units PixelsPerInch -density 300x300 $i.pdf

seems to do the job!
Thanks for your help, snibgo!
By the way, the generated pdf seems a bit fuzzy when zoomed in, would setting the dpi to something making for a rounder division help?

[snibgo]

You enlarge by a factor of ten or so. But this doesn't create new detail, so it will look fuzzy.

[monpantalon]

Makes sense; changing the unit to PixelsPerCentimenter also works, since I get a cleaner fraction.
Thanks again!