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What is the best dpi for A3 output?

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  #1  
Old 01-12-2012, 04:40 PM
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What is the best dpi for A3 output?

Hi everyone,
(a bit urgently)

I have A3 size poster made for a client which will go for print.
Image is way bigger then A3 so I will have to resize it to A3.
How much of bleed should I leave and what is the ultimate dpi for this kind of print? Also printer asked for a tiff file. I have flattened tiff image as it was a size of nearly 2GB. Anything else you would suggest me how to prepare the file?
Thank you in advance
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Old 01-13-2012, 12:24 AM
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Re: What is the best dpi for A3 output?

Hi nebula

No one has jumped in and I am not the expert. Most of these questions should come directly from the printer (website or phonecall). Some of this you probably already know.

- RGB vs CMYK
- In which color space or ICC profile are they expecting the image? Convert to that color space before saving file. I would attach ICC profile unless printing company specifically does not want it attached
- 8 bit vs 16 bit output (almost all as I recall are 8 bit yet some accommodate 16 bit)
- Bleed is specific to the printing company. Common is 2mm to 5mm
- You made no mention of the number of pixels per edge of your existing image. I would not know if you would need to resize up or down both because of that and also you are asking which dpi to use. Again, the printing company can tell you what is ideal for their equipment. From a viewing standpoint at 25cm distance the average eye can distinguish 5lp/mm (line pairs per mm). This translates to 254 dpi so the range of 240 to 300 dpi is excellent. Most don't view such size posters at that distance. If viewing distance increases proportionally to paper size (1.4X) then the needed dpi could be reduced by the same amount for a range between 170 and 212 dpi.
- For resizing I have had good luck with just using Image Resize in Photoshop (some swear by Perfect Resize 7 by onOne Software). Use the recommended re-sampling algorithm as suggested in the Image Resize dropdown. Also, view the image at 100% to look for resizing artifacts
- I would also suggest Proofing the image in Photoshop using the ICC profile/color space with which you will be outputting the file. This helps reduce surprises on how it will look when printed. Ideally you could try a test print with the printer (portion of image or smaller size).

Again, I am not the expert so maybe other forum members will add a post.
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Old 01-13-2012, 03:04 AM
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Re: What is the best dpi for A3 output?

hi John,

Thanks for reply. I know I'll have to scroll a lot if you reply

This will be sRGB
I have attached ICC profile
8bit
I've red it is 3mm in UK. but as you say depending on the company is valid point.
I will have to resize it as the existing pixels are 7530 x 11464 when resized using resample option it drops down to around 3542 x 5350 pixels.

I just realise from your post that this is me and printer communication too. It is my first time when I do post for that reason I obviously noob how the whole procedure works.
Someone has mentioned that I should talk to printer directly this would also eliminate unnecessary hassle though.
Have you ever heard of any kind of bleed in the shadow area when A3 printed due 300dpi set. ( I found a post on flickr )

Many thanks Tomas
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Old 01-13-2012, 04:19 AM
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Re: What is the best dpi for A3 output?

John covered everything I can think of!

3 mm bleed, 300 ppi, would be common settings for print and I would use this as a starting point unless you get anything else specified from the printer.
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Old 01-13-2012, 04:27 AM
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Re: What is the best dpi for A3 output?

Quote:
Originally Posted by Chain View Post
John covered everything I can think of!

3 mm bleed, 300 ppi, would be common settings for print and I would use this as a starting point unless you get anything else specified from the printer.
Hi Chain,

Thanks for jumping in. Talking about bleed would it be reasonable to have bleed of its own photo rather then white. Thanks Tomas
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Old 01-13-2012, 05:21 AM
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Re: What is the best dpi for A3 output?

Yes, the image should extend all the way into the bleed. If there was nothing in the bleed (white) it would be pointless.

The "bleed" area will be printed, but cropped off when they cut the paper. It is there so that when they crop it slightly inaccurate (off by 1 mm, roateted slightly, etc.) you won't get an ungly white border on your print.
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Old 01-13-2012, 05:22 AM
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Re: What is the best dpi for A3 output?

Thank you Chain,

Clear as crystal.
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Old 01-13-2012, 11:53 AM
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Re: What is the best dpi for A3 output?

Quote:
Originally Posted by nebulaoperator View Post
hi John, Thanks for reply. I know I'll have to scroll a lot if you reply
Well Tomas, if you are implying that I am bombastic, circumlocutory, diffuse, flowery, full of air, fustian, gabby, garrulous, grandiloquent, involved, loquacious, magniloquent, palaverous, periphrastic, pleonastic, prolix, redundant, repeating, repetitious, repetitive, rhetorical, talkative, talky, tautological, tautologous, tedious, tortuous, windy, yacking you are probably right. Except for the "full of air" part. More accurately that would be "full of hot air"

Sounds like Chain has you covered. I am less than a noob on the bleed specifications yet wanted to through in a couple tidbits to make sure we are on the same page based on a comment you made about shadow area. My understanding of the bleed specifications is to make sure in a print that once "cut" there are no undesired white boundary edges. I thought the extra print size needed on the edges (the bleed spec) was mostly to accommodate the inaccuracies of the print and cut process and making sure that you don't end up with any white framing. (see http://en.wikipedia.org/wiki/Bleed_%28printing%29) While there is some actual "bleed" of ink on the paper that may help reduce the amount "bleed area" that is needed, the printing service knows what is needed for both. In the past (maybe today as well) I know there was high sensitivity and concern of too much bleed area since this would waste ink and paper and in some cases would bump you up to a larger size printing plate and or paper size (read higher cost). Again, the printing service can advice about any such concerns for their equipment. Someone in PrePress would be much better qualified to comment on this.

On another angle though, here is a link to a description of the printing origins of the term "Full Bleed." It had nothing to do with ink bleeding on the paper so was a fun read. I must admit I have not confirmed the accuracy of this article.:
http://www.mediapost.com/publications/article/93684/full-bleed.html

So I hoped you enjoyed the extra info and I at least hope that this post removes all aspersions and doubt about my verbosity
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Old 01-13-2012, 12:59 PM
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Re: What is the best dpi for A3 output?

Talk about bleeding edge

John you have caused me some work as I am going to have to look up some of the words in your first paragraph
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Old 01-13-2012, 01:27 PM
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Re: What is the best dpi for A3 output?

Quote:
Originally Posted by Tony W View Post
John you have caused me some work as I am going to have to look up some of the words in your first paragraph
Let me know what you find out, I just cut and paste some online synonyms. On second thought......... don't let me know
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