Exporting large size PDF from photoshop
I have create PSD file in photoshop on A3 (~12 X 18 Inch) size Canvas. Now I would like to export PDF format from it in A1 size (~24 X 36 Inch) for A1 size paper printing.
Unfortunately while exporting PDF Or Saving PDF it does not asks for dimension. And exports the PDF document in save PSD size.
I tried but could not find right solution. Now I sure don't want to spend time creating large size PSD. Some solution/information would really help thanks.
You have 2 options, and unfortunately you can't really change easily the size of a PDF while exporting it:
1) Similar to what Mamoon mentions, you could create a document in InDesign or Illustrator to the final size you want, and import that Photoshop file in it. You will lose some quality in the process if your resolution is 200-300ppi. That's not the ideal solution in your case and you should still change your resolution In Photoshop first.
2) You can simply go in "image size" in the "image" top menu of Photoshop, and change the size of your poster there.
Now be careful: depending on the resolution you need for printing and what kind of machine it will be printed on, you can't change the resolution and size simply like this. You need to verify a few things first.
If you are printing for offset, you should uncheck the box "resampling" before you get started; you should see the link icon linking the resolution and the width/height all together. Once you see this, lower your resolution to 200ppi; you will notice your file has increased in size (see this link if you want to know why.)
You will get a size of 18 x 27". Then check the "resampling" checkox, and change the width and height values to 24" x 36". This time the resolution will not change.
Now, change the resolution to 266dpi (the dimension of the file will not change.) You can also change it to 300dpi, the file will be a bit more blurry but it won't be dramatic. In doubt, look at your image at 100% and if it's alright with you, that means it will be alright for printing too.
You now have a 24x36" poster that you can export as PDF (See this url to keep your text layers in vector for maximum quality!)
If you're printing on a large format such as Epson Stylus or just a few samples of your poster, you can use a 200dpi resolution for your file. Just do the same steps as above but don't "boost" the resolution to 266dpi, keep it at 200dpi. Then you can export your PSD file at the right size.
You should ask your printer what resolution he prefers to receive the file in. The ones I indicated are acceptable standards but your printer could require 300dpi in both case.