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View Full Version : Producing an A2 size poster. Please help!


jademcquade
02-08-2007, 02:40 PM
Hi chaps.

I am currently in the process of scanning pieces of art work I have made recently. These are various pieces of painting done on pieces of card just under a4 size.

My question is this:

If I want to be able to print them out at a size of A2, for my poster, what Dpi am I best to scan my images at. My scanner supports 50, 75, 100, 150, 200, 300, 400, 800, 1200 as output resolution.

Which setting should I choose to give me the best proffesional looking print?



PS I am aware of the increase in file size of the image with higher dpi settings.

jipe
02-08-2007, 02:53 PM
i am assuming that you want each a4 piece to have its own a2 poster.

if so, the DPI at which you scan your images depends upon one very important thing: what DPI your printer requires for the poster print.

if they tell you 200 DPI (or anything lower, like 150), you should be able to scan each a4 image at 400dpi, then uncheck "resample image" and change the DPI to 200. the new width and height should give you a2 size almost exactly, at 200 DPI.

if your printer wants 300 DPI, you'll have to scan your images at something higher.. i guess the next step is 800 DPI for your scanner, which will give you a little extra detail.

if my assumption at the beginning was incorrect, and you're instead creating a type of collage of all your a4 images into one poster, then it depends on how large each image is on the poster - but i think 300 DPI will do just fine.

find out what DPI is optimal for the place where you'll be printing the posters, and shoot for that. good luck!

jademcquade
02-08-2007, 03:17 PM
Hi Jim.

Yeah I want each piece to be an individual a2 size poster. OK I guess the next step is to find a printer and see what specification they require from me.

Wouldn't it be good if they all used the same standards or formats.

Thanks for the reply.

khurrum_j
02-08-2007, 03:40 PM
Hi jademcquade.

I should explain my workflow. So you'll know these methods are tried and tested.

I print a lot of posters ranging in size from A3 all the way upto A0. My images come from all sorts of places, i.e. scanners, cameras, other software, etc.

When I scan, I leave the resolution to at least 300dpi. And most of the time, these settings are set as default for both B&W, GREYSCALE as well as COLOR images. My prints come out with nice colors and good quality. No issues. Also, I use different printing shops, just in case one of them isn't ready to take my orders for any reason. So its also a good idea to keep at least two shops in sight. This will help a lot when you're on a deadline!

BOTTOMLINE:

- Make sure the source images are of at least 300dpi/600dpi.

- Size of the image in pixels doesn't matter. Once you've scanned your sources, make a new file in PS/Ill/CorelDraw/Xara, etc. Size this new file A2, or whatever size you want in final output.

- After touchup/cleanup of your sources, just bring them on this new A2 canvas. And your done!

- Usually, I scan at a higher resolution (dpi), then downsample the images after cleaning up. The results are very professional.

Its a long post, but I hope this helps.

Best,

KHURRUM

jademcquade
02-08-2007, 09:46 PM
Hi Khurrum,

So i can scan my image at about 300dpi, then open the image in Photoshop and resize the image to A2 size. Then the new A2 sized image can be taken to the printers as it is and will print out in good quality?

Would that work?

Collember
02-09-2007, 02:05 AM
It doesnt matter what physical size the photos are, aslong as they remain at 300dpi. By this i mean, say u scan ur photo at 300dpi, and it comes out to being 1000mm square lol, as long as you resize it down to an A2 page BUT keep the dpi at 300dpi, the quality will only change as much as the pixels that need to be recalculated by photoshop's resizing software.


As long as ur image is at 300dpi+ if the print house has to do any changes, they will be happy to do anything to it. I work with very bad quality photos all the time at work, and its such a relief to get a 300dpi one every once in a while lol

khurrum_j
02-09-2007, 07:37 AM
Agree with Collember.

I've mentioned the process in my earlier post, but I'll try to make it simple.

1- In Photoshop, create a NEW document. Size it A2 from the dialog box that pops up.
You can get the sizes in mm or in from here: http://painting.about.com/od/artglossarya/g/defApapersizes.htm

2- Bring in your scan at 300dpi in Photoshop.

3- Drag your scan to the A2 file you created in step 1.

4- After you drag the scanned image on the A2 canvas, you might notice your image
is either smaller than your A2 or bigger. In either case, just CTRL-T to enable FREE TRANSFORM, then scale your image to fit the A2 canvas.

Its really very simple.

Once your done, just save your A2 in either TIFF, PDF, or flattened PSD.

If your still unsure, lemme know so I can do a small video to demonstrate. Or you can reach me on google chat.

KHURRUM

evanfotis
02-09-2007, 11:27 AM
Guys, computers do not understand actual sizes, like inches, millimeters etc.
They measure images in pixels.
So a 3200X2300 px image will become an A4 if printed at 300dpi or an A3 if printed at 150dpi.

The point is not to resample inside Photoshop (which you can but not its not optimum) but to scan in with as much information/resolution needed for the output.

As for printer dpi settings, the larger the paper size to be printed (A2+) the lower the relative dpi setting needed.
Meaning that at A4 size paper you will see a visible difference between a 300dpi (2300x3200px) file and an 150dpi (1600x1200px) one.
But at large sized prints even 100-150 dpi at actual paper size will be OK.

I used to create some huge 7Kx4K images to be printed at 100X130cm, only to find that the printer bureau would ... down sample them to 100x130@100 or 150dpi!
So:
If you want your A4 scans to look good for an A2 size print (60x40cm), scan in at roughly 3600X2500 pixels or as mentioned before A4 @300dpi. That will give you an A2 @ 150dpi, which will be sufficient.

jademcquade
02-10-2007, 01:47 PM
Thanks to all for advice. I know what I am doing now!

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