DPIs of images in PDFs

TwistMyArm · 06-23-2008, 03:30 PM

Hi all,

I have a collection of PDFs that I will be printing at varying dimensions. Does anyone know how I could go about analysing the images embedded in the PDF to determine the 'DPI' of each image in the actual printout?

In reality, I can work out everything I need, so long as I can work out the dimensions of the 'element' that the images are in in the PDF.

Hopefully that makes sense to somebody: if not, feel free to say! I'm looking to do it with PHP in a Linux environment. I have tried with pCOS but apparently it's not possible, though I'm happy to be corrected.

If I need to pay for a library, I'm happy to do so, so long as the price, support and reliability are right.

Thanks...

mholt · 07-10-2008, 05:19 PM

I don't know much about Adobe Acrobat products, but you may need more than just Adobe Reader to extract the images and get their DPI... it may require a full version of Adobe Acrobat.

weblord · 07-10-2008, 05:58 PM

you set the DPI in the print driver - in Windows XP,
for Adobe, go to the Control Panel, open the Printers, right-click on "Adobe
PDFWriter", then select properties. Click on "Preferences", "Page Setup",
then select the resolution in the "Graphic" section.

but if you do your design just for online purposes usually 72dpi is ok for .pdf images

Quote:

Originally Posted by TwistMyArm

Hi all,

I have a collection of PDFs that I will be printing at varying dimensions. Does anyone know how I could go about analysing the images embedded in the PDF to determine the 'DPI' of each image in the actual printout?

In reality, I can work out everything I need, so long as I can work out the dimensions of the 'element' that the images are in in the PDF.

Hopefully that makes sense to somebody: if not, feel free to say! I'm looking to do it with PHP in a Linux environment. I have tried with pCOS but apparently it's not possible, though I'm happy to be corrected.

If I need to pay for a library, I'm happy to do so, so long as the price, support and reliability are right.

Thanks...

TwistMyArm · 07-10-2008, 06:04 PM

Quote:

Originally Posted by weblord

you set the DPI in the print driver - in Windows XP,
for Adobe, go to the Control Panel, open the Printers, right-click on "Adobe
PDFWriter", then select properties. Click on "Preferences", "Page Setup",
then select the resolution in the "Graphic" section.

but if you do your design just for online purposes usually 72dpi is ok for .pdf images

Thanks weblord... I guess it wasn't as obvious as I was hoping, but I'm actually after a programmatic way of doing it (for a website, in particular).

The problem is that I'm not the one actually creating the PDFs...

weblord · 07-10-2008, 06:07 PM

If that's the case then there's a need to know the pdf creator software that your programmer will use, advise him/her to get to the specific dpi you want.
dpi of images are not that important to be huge, since .pdf has built-in resolution fixer for images, it's not a big deal.
setting it up as 300dpi will make your .pdf bloated and will usually hang on load time.
setting it up like 72dpi is the set standard

Quote:

Originally Posted by TwistMyArm

Thanks weblord... I guess it wasn't as obvious as I was hoping, but I'm actually after a programmatic way of doing it (for a website, in particular).

The problem is that I'm not the one actually creating the PDFs...

mholt · 07-10-2008, 06:30 PM

Quote:

Originally Posted by weblord

If that's the case then there's a need to know the pdf creator software that your programmer will use, advise him/her to get to the specific dpi you want.
dpi of images are not that important to be huge, since .pdf has built-in resolution fixer for images, it's not a big deal.
setting it up as 300dpi will make your .pdf bloated and will usually hang on load time.
setting it up like 72dpi is the set standard

Yeah but if you intend to print it you will need something above 200 DPI to look decent. In case you didn't notice his first phrase: "to print at various dimensions", the larger you print the larger the image would have to be (filesize), of course.

weblord · 07-10-2008, 06:32 PM

ive already answered that read this:
http://www.namepros.com/2906998-post5.html
my given option is from 72dpi to 300dpi
that solves it.

Quote:

Originally Posted by mholt

Yeah but if you intend to print it you will need something above 200 DPI to look decent. In case you didn't notice his first phrase: "to print at various dimensions", the larger you print the larger the image would have to be (filesize), of course.

mholt · 07-10-2008, 06:38 PM

Quote:

Originally Posted by weblord

ive already answered that read this:
http://www.namepros.com/2906998-post5.html
my given option is from 72dpi to 300dpi
that solves it.

You can't just print a 72 dpi image at 300 dpi. Your image will be not even 1/3 the size it shows up as on the screen. You need to format the image in the first place - before placing it in a PDF - to be above 200 DPI to be acceptable for good printing.

weblord · 07-10-2008, 06:40 PM

format it at 300dpi and print at 300dpi res on screen and printer
i've already answered that as well
http://www.namepros.com/2906988-post3.html

Quote:

Originally Posted by mholt

You can't just print a 72 dpi image at 300 dpi. Your image will be not even 1/3 the size it shows up as on the screen. You need to format the image in the first place - before placing it in a PDF - to be above 200 DPI to be acceptable for good printing.

mholt · 07-10-2008, 06:44 PM

Quote:

Originally Posted by weblord

format it at 300dpi and print at 300dpi res on screen and printer
i've already answered that as well
http://www.namepros.com/2906988-post3.html

It looks like he's not making the PDFs, though, just has a collection of them, so that point doesn't matter.

weblord · 07-10-2008, 06:49 PM

for the op as well kindly rethink how you approach this? btw maybe pdf is not the solution, because pdf is made to be portable and small in file size not intended for high resolution printing but just for portable quick reading on the computer

but if you have the pdf's already you need a converter
http://www.google.com.ph/search?q=pd...ient=firefox-a

http://www.123fileconvert.com/

TwistMyArm · 07-11-2008, 04:35 PM

Thanks for all the posts guys. The thing is, this is not really something where I can change the approach: I'm coding up a web interface to a print shop that is to automate the checking of random jobs that are being uploaded by clients...

I think I may have found a program that will let me check the image details: if anyone is interested, I'll let you all know the result.

06-23-2008, 03:30 PM	#1 (permalink)
TwistMyArm NamePros Member Join Date: May 2006 Posts: 160 81.00 NP$ (Donate)	DPIs of images in PDFs Hi all, I have a collection of PDFs that I will be printing at varying dimensions. Does anyone know how I could go about analysing the images embedded in the PDF to determine the 'DPI' of each image in the actual printout? In reality, I can work out everything I need, so long as I can work out the dimensions of the 'element' that the images are in in the PDF. Hopefully that makes sense to somebody: if not, feel free to say! I'm looking to do it with PHP in a Linux environment. I have tried with pCOS but apparently it's not possible, though I'm happy to be corrected. If I need to pay for a library, I'm happy to do so, so long as the price, support and reliability are right. Thanks... __________________ Free Fuel Efficiency Calculator \| CMS Book Store

07-10-2008, 05:19 PM	#2 (permalink)
mholt DNOA Member Join Date: May 2004 Location: Utah Posts: 5,041 18.01 NP$ (Donate)	I don't know much about Adobe Acrobat products, but you may need more than just Adobe Reader to extract the images and get their DPI... it may require a full version of Adobe Acrobat. __________________ codeboards A high-quality community of programmers -- Join today and post! We want new members!

07-11-2008, 04:35 PM	#12 (permalink)
TwistMyArm NamePros Member Join Date: May 2006 Posts: 160 81.00 NP$ (Donate)	Thanks for all the posts guys. The thing is, this is not really something where I can change the approach: I'm coding up a web interface to a print shop that is to automate the checking of random jobs that are being uploaded by clients... I think I may have found a program that will let me check the image details: if anyone is interested, I'll let you all know the result. __________________ Free Fuel Efficiency Calculator \| CMS Book Store

07-10-2008, 06:49 PM	#11 (permalink)
weblord NamePros Legend Join Date: Dec 2005 Location: Philippines - www.Nabaza.com Posts: 19,840 21,700.43 NP$ (Donate)	for the op as well kindly rethink how you approach this? btw maybe pdf is not the solution, because pdf is made to be portable and small in file size not intended for high resolution printing but just for portable quick reading on the computer but if you have the pdf's already you need a converter http://www.google.com.ph/search?q=pd...ient=firefox-a http://www.123fileconvert.com/

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)