# Canvas print



## Gunna (Feb 13, 2013)

I have a landscape image 3973 x 2649 pixels [24 bit depth, whatever that means] 5.8 MB
I want a canvas print 30" x 20"
Printer wants al least 100 DPI
I understand that 3973 pixels divided by 30" = 108 PPI
I'm told DPI is not the same as PPI ??
Exporting from LR gives me a choice of PPI
What PPI should I select in LR, to export this image the the printer?

I hope that makes more sense to you than to me!


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## Kiwigeoff (Feb 13, 2013)

Gunna,

PPI and DPI are effectively the same for this purpose.
Export with these settings:



It is fine to have a bit more resolution than too little.


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## Gunna (Feb 14, 2013)

Thanks Geoff - from across the 'channel'.
I was still confused, so I -
cropped to the same ratio as the canvas I want,
didn't ask LR to resize,
put in 108 DPI [being the calculated PPI for the canvas size],
& exported.  Sent that to the canvas printer.
I hope that maximises the quality of the print, without any kind of 're sizing' work, which I dont understand.
As I will get some more canvas prints later, any comment on what I did would be appreciated.


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## LouieSherwin (Feb 14, 2013)

Hi Gunna,

Your printer is not helping by using the confusing DPI (dots per inch) term, but, as Geof points out what they are really referring to PPI (pixels per inch). 

A digital image file doesn't really have any physical dimensions, it just contains a certain number of pixels or in your case 3973 x 2649. It doesn't acquire any density (per inch, per cm, etc.) until you actually create a physical display or print from that file. So if you were to create a print that is 10 inches wide from this file the density for that print would be 397 PPI (3973 pixels / 10 inches). For a 30 inch wide print the density will be 132 PPI (3973/30). 

If for example your image was only 2500 x 1875 for example than a 30 inch print would only be 83 PPI (2500/30). Depending on the actual content of the image this could in fact make a very nice large print when viewed at a reasonable distance. If you get up and examine it a 12 inches you will probably will notice that certain detail features are fuzzy. However, if you stand back at 5 feet or more it probably will look great. I once saw a very nice large print in an airport concourse, at least 60 inches wide, of the Seine in Paris. Out of curiosity I walked up and examined it from 12 inches and sure enough the details were all quite fuzzy from that distance. It was and still is a good reminder that there many things about our craft that are a good more important then the absolute sharpness of every pixel in our images.

You can certainly add a PPI value to your image but that is informational only and is only used to calculate a suggested physical dimension and has no effect on how the image will be printed. 

To add to the confusion printer manufactures promote the term DPI (dots per inch) to describe their printer resolution. Technically this refers to the minimum size of ink droplets that a specific model printer can produce and is NOT the same as the image resolution (PPI) that the printer can produce. Neither Canon, Epson nor HP will tell anyone what the actual PPI is of any of their printers. They are stuck in a marketing war over the who has the most DPI. Best guess is that all of these manufactures have an actual PPI of around 200-300. Since starting to use Lightroom I have stopped worrying about this. The Lightroom print engine does a fantastic job of optimizing the print output. It does a much better job printing that I ever could from Photoshop when I was spending hours futzing with PPI and sharpening for output etc.

Ok enough... Hopefully you will find some of this helpful.

Bottom line send your file to the printer and see how it comes out. Your image is well within the parameters needed to produce a quality print of that size to be viewed at a normal viewing distance.

-louie


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## Brad Snyder (Feb 14, 2013)

To put things in perspective (oops, word play not intended), the reigning "Worlds Largest Video Display" is at Charlotte Motor Speedway in North Carolina, US. The display is 200 feet wide by 80 feet tall (61x24m) with a pixel dimension of 2000 x 784, which works out to about 10 pixels per foot, call it 33 pixels per meter.  I'm sure the beer advertisements look fine.


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## Gunna (Feb 15, 2013)

Thanks guys.
Louie - that was most helpful!  Yes, the PPI on my shot was in fact 132 [my bad maths], & that is what I told LR to export it as.
Question - Is there any point in making the PPI higher in this instance?
I was concerned when the Printer said that he wanted 100 DPI minimum - that I wasn't giving him much more than that, as the image's maximum for the printed size.
I will report back when I get the canvas!


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## LouieSherwin (Feb 15, 2013)

Hi,

First off at a normal viewing distance for a 30 inch wide print on canvas the minimum recommended of 100 PPI going to be more than enough. This is in fact about what you get when you view your image at 1:1 in Lightroom. Most LCD monitors these days have about 100 PPI. So if the image looks fine at 1:1 on your screen then it will look good at this the size you are printing.

Also keep in mind that the viewing distance plays an extremely important role. As Mark pointed out the pixel size of the Charlotte Motorway screen is huge but because all the viewers are dozens and even hundreds of yards away the image everyone sees is sharp and clear. The visual system of the human being is quite amazing in this respect. 

The Impressionist painters in France, Monet et. al. among other things were playing around with this. There is one painting in particular that I remember seeing that demonstrated this. If I stood close, up to 6 feet away, it just looked like an amorphous collection of colored blobs of paint. But, as I moved back somewhere at 9 or 10 feet the image suddenly popped into view. It was quite interesting to just move slowly forward and backward and watch as the image appeared and dissolved. What amazed me among other things was how he painted it at all. Because at the distance where you could see the image you would need brushes at least 10 feet long. I guess that he moved forward and backward as he painted so maybe he had to walk a 100 miles just to paint one picture. I don't know but it fun to see and fun to speculate.

-louie


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## daz26 (Mar 12, 2013)

Thanks for the replies, they've helped me greatly.


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