Convert large PDF to smaller with higher DPI?

[expresspotato]

Hi,

Does anyone know how I can convert a larger PDF at 96 DPI (34x44 inches) at 3,264 x 4,224 to an 384 DPI 8.5 x 11?

I tried the following without success, the PDF's generated are always 72x72 when using the identify --verbose

convert -density 96 statement.pdf -density 384 statement-converted.pdf
convert statement.pdf -resample 384 statement-converted.pdf

Resample takes literally forever even on an i7 so looking for a snappy solution also.

[root@localhost external]# identify -verbose statement-converted.pdf
Image: statement-converted.pdf
Format: PDF (Portable Document Format)
Class: DirectClass
Geometry: 2448x3168+0+0
Resolution: 72x72
Print size: 34x44

Thanks,
Kevin

[fmw42]

I do not understand. You have two commands working on the same input? Why? Your first command does nothing but change the density. There is no resize of the pixels

I would recommend that you simply -resize the PDF to the number of pixels you want and then set the density to generate the number of inches you want or whatever density you want. Be sure you set the -units as well.

Please let us know your IM version and platform, since syntax changes. You might also upload your file to some free hosting such as dropbox.com and put the URL here. Then let us know what density, units and desired inches or pixels you want. Did you want a specific size in pixels or inches at the desired density and units? Or do you want some specific pixel size and inches and use whatever density and units desired?

We can probably help better with more information.

Your listing above does not tell us the PDF units. What is that? If empty, you probably should specify the units as well as the density of 96 before reading your PDF.

[fmw42]

Geometry: 2448x3168+0+0

This does not agree with your statement

96 DPI (34x44 inches) at 3,264 x 4,224

[expresspotato]

convert statement.pdf -resample 384 statement-converted.pdf

Weird I could have sworn it was 96 DPI. Oh well looks like the original is 72. Sorry if I'm not being clear. I just want the large pdf to be 8.5x11 inches, currently 34x44 inches. Because its being printed thought the best way would be to retain all the pixels and just increase the DPI. None of these commands seemed to increase the density. Shouldn't the resolution stay the same?

Thanks for all your help.

# identify -verbose statement.pdf | head
Image: statement.pdf
Format: PDF (Portable Document Format)
Class: DirectClass
Geometry: 2448x3168+0+0
Resolution: 72x72
Print size: 34x44
Units: Undefined
Type: TrueColorAlpha
Endianess: Undefined
Colorspace: sRGB


# convert statement.pdf -resample 384 statement-converted.pdf

# identify -verbose statement-converted.pdf | head
# Image: statement-converted.pdf
Format: PDF (Portable Document Format)
Class: DirectClass
Geometry: 2448x3168+0+0
Resolution: 72x72
Print size: 34x44
Units: Undefined
Type: TrueColorAlpha
Endianess: Undefined
Colorspace: sRGB


# convert statement.pdf -units PixelsPerInch -resize 2488x3168 -density 300 statement-converted.pdf
# identify -verbose statement-converted.pdf | head
Image: statement-converted.pdf
Format: PDF (Portable Document Format)
Class: DirectClass
Geometry: 588x760+0+0
Resolution: 72x72
Print size: 8.16667x10.5556
Units: Undefined
Type: TrueColorAlpha
Endianess: Undefined
Colorspace: sRGB


# convert statement.pdf -units PixelsPerInch -density 300 statement-converted.pdf
# identify -verbose statement-converted.pdf | head
Image: statement-converted.pdf
Format: PDF (Portable Document Format)
Class: DirectClass
Geometry: 588x760+0+0
Resolution: 72x72
Print size: 8.16667x10.5556
Units: Undefined
Type: TrueColorAlpha
Endianess: Undefined
Colorspace: sRGB


Is the Resolution not density?

# convert --version
Version: ImageMagick 6.7.8-9 2016-06-16 Q16 http://www.imagemagick.org
Copyright: Copyright (C) 1999-2012 ImageMagick Studio LLC
Features: OpenMP

[fmw42]

I believe the problem is that PDF is a vector format and does not have or save to any particular density. IM puts 72 dpi as default.

If you change the PDF to some raster format, then you can save the density and units.

Note you have to specify the density and units before reading the PDF when converting it to raster format.