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NikeMeyer
Participant
September 5, 2018
Answered

Over-sized file vs high dpi

  • September 5, 2018
  • 4 replies
  • 637 views

Is there a difference in working on an over-sized file at 72 dpi vs working at a higher dpi at the correct size right off the bat?

I really apologize if this question is super ignorant.  I've read a few articles and forum conversations, but I was still unclear.

My client is wanting a large poster map.  I'm currently working at 3500 x 5000 pixels (about 49"x70" - far larger than I'll need it to be) for just one portion of the map, but I'm working at 72 dpi so that the file size doesn't get out of hand.  From what I've read, it seems I should be working at at least 150 dpi in order to ensure it prints crisply.  Is that correct?

I haven't worked on a print project this large before and I'm trying to figure out how best to balance quality and work-ability.  Since it's a map it really needs to be crisp even when viewed closely.  Any help appreciated!

This topic has been closed for replies.
Correct answer rob day

Is there a difference in working on an over-sized file at 72 dpi vs working at a higher dpi at the correct size right off the bat?

(about 49"x70" - far larger than I'll need it to be)

There isn't because the width and height are the print output dimensions. When it comes time to print, you will either have to resize the map to the desired print dimensions (Resample unchecked in the Image Size dialog), or scale the map in a page layout application like InDesign. When you resize or scale the image (no pixels added or subtracted), its output resolution changes. Your 3500x5000 pixel image printed at 11.7" x 16.7" would have an output resolution of 300ppi. If the map has high contrast lines and text 150ppi would not likely be adequate.

but I'm working at 72 dpi so that the file size doesn't get out of hand

Note that the file size doesn't change when you uncheck Resample and make a dimension change. 49" x 70" at 72ppi has the same file size as 11.7" x 16.7" at 300ppi

4 replies

rob day
Community Expert
rob dayCommunity ExpertCorrect answer
Community Expert
September 5, 2018

Is there a difference in working on an over-sized file at 72 dpi vs working at a higher dpi at the correct size right off the bat?

(about 49"x70" - far larger than I'll need it to be)

There isn't because the width and height are the print output dimensions. When it comes time to print, you will either have to resize the map to the desired print dimensions (Resample unchecked in the Image Size dialog), or scale the map in a page layout application like InDesign. When you resize or scale the image (no pixels added or subtracted), its output resolution changes. Your 3500x5000 pixel image printed at 11.7" x 16.7" would have an output resolution of 300ppi. If the map has high contrast lines and text 150ppi would not likely be adequate.

but I'm working at 72 dpi so that the file size doesn't get out of hand

Note that the file size doesn't change when you uncheck Resample and make a dimension change. 49" x 70" at 72ppi has the same file size as 11.7" x 16.7" at 300ppi

N
NikeMeyerAuthor
Participant
September 5, 2018

Ok, that's what I was wondering!  So, as long as the print dimensions (when changed to 300 ppi, not resampled) are still large enough for my needs, I'll be fine either way.  I could've just started off with the correct specifications and saved myself the trouble

It seems I've just been going about it backwards, but I think I get it now!  Thank you so much!!

Simmer1
Community Expert
Simmer1Community Expert
Community Expert
September 5, 2018

It depends on your end clients printers requirements, so its best to check with them.

When printing at 72ppi you run the risk of ending up with poor quality prints.

T
Test Screen Name
Legend
September 5, 2018

Photoshop should do just as good a job. It's just that you are shovelling tons of pixels for very little benefit.

T
Test Screen Name
Legend
September 5, 2018

If you are drawing the map (rather than working with a scan, photograph, or computer generated image file), then Illustrator seems a more logical choice than Photoshop.

N
NikeMeyerAuthor
Participant
September 5, 2018

Yeah, probably.  Thing is, I'm normally a digital painter and I do my art in Photoshop.  Never really invested a lot of time in working with Illustrator, so that's just where I'm at with this one ¯\_(ツ)_/¯

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