Printing Canvas, Resolution/DPI

[Coplestone]

Hello guys,

In terms of printing canvas art, what would be the ideal resolution and DPI for the dimensions:

40" x 26"

Thanks.

 

[Kodiak Qc]

•
DPI = PPI!

So. 300 ppi x 40 in = 12 000P
and 300ppi x 26 in = 7 800P

Got it?

 

[Coplestone]

•
DPI = PPI!

So. 300 ppi x 40 in = 12 000P
and 300ppi x 26 in = 7 800P

Got it?

Hi there,

Thanks for the reply.

I understand that dot per inch and pixels per inch mean the same thing, however what is meant by the 'P' at the end of of the resulting numbers?

Thanks.

 

[Kodiak Qc]

So. 300 ppi x 40 in = 12 000P
and 300ppi x 26 in = 7 800P

ppi = pixel per inch which reflect the pixel density
p = pixel which gives the length, here, you canvas will be 12 000 pixels long-

 

[Coplestone]

ppi = pixel per inch which reflect the pixel density
p = pixel which gives the length, here, you canvas will be 12 000 pixels long-

Ah I see, this is being calculated in regards to a program such as Photoshop.

I'm referring to a 40" x 26" canvas after being printed and hung. I was wondering what resolution and dpi would an image have to be to look decent on that sized canvas after being printed.

Thanks.

 

[Kodiak Qc]

resolution and dpi

•

At 300 ppi, the size would be 12 000 x 7 800 = 93,6 MP

 

[admirable]

With something that size, anything above 150 would be ok...............depending on the image and the printer knowing his stuff obviously

 

[Coplestone]

Ahhh so 300 dpi being optimal quality for print and 12000x7800 being pixel size of the image.

Thanks.

 

[Coplestone]

With something that size, anything above 150 would be ok...............depending on the image and the printer knowing his stuff obviously

I see,

I sent them an image that was originally 2000x1333 @ 300 dpi.

I've uploaded what I managed to do to it in Photoshop and the original.

Upload:

Original: https://mega.nz/#!IBInSIyC

After: https://mega.nz/#!hI4RTTjB

Decryption Keys (for image downloads):

!l_6mxEtadUFWw0gZ-mha-OUf3k3uR8ICmBZYNWeiZkM

!hX9KOSdQ_QICKLCgwZvV-6PNhG445bRFVqc6jSWyLaM

I've even gone as high as 12000x7800 @ 200dpi and the quality of the image is still pretty good in photoshop.

Is this how they would edit the image for print? I have already emailed them over my concern.

**edit** disregard the attached file.

 

[Willid1]

This has been asked many times before. Don't bother tring to work it out, just send them the biggest un interpolated file you have in as big a file size as you can manage and the printers software will size the image appropriately for their printing.

Canvas is very forgiving of detail and at that size and infact as said above 150 ppi will be plenty.

HTH

David

 

[Coplestone]

This has been asked many times before. Don't bother tring to work it out, just send them the biggest un interpolated file you have in as big a file size as you can manage and the printers software will size the image appropriately for their printing.

Canvas is very forgiving of detail and at that size and infact as said above 150 ppi will be plenty.

HTH

David

Oh, well that's fair enough.

Doesn't dimensions matter a lot here then? Wouldn't 2000x1333 @300dpi be too small for 40"x26"?

Or is it mostly about DPI?

Thank you.

 

[StewartR]

If your original image is 2000 x 1333 pixels, then at 40 x 26 inches it works out to 50 ppi. (2000 divided by 40 is 50.)

Thats really not very much. Canvas is quite forgiving, but probably not that forgiving. The usual rule of thumb I've seen suggested for canvas is 100 ppi, which would imply printing no larger than about 20 x 13 inches.

Remember, in principle you can upscale your image to whatever pixel dimensions you wish, but at the end of the day you only have 2000 x 1333 pixels of actual data and that's what counts.

Out of curiosity, why is the original so small? It's less than 3 mega pixels.

 

[retrosi]

PPI & DPI are NOT the same thing, fact.
PPI relates to your monitor or anything with a screen and the pixels that it has.
So you can have a 24 inch monitor that is 1920x1080
or you can have a 50 inch TV with the same 1920x1080
So clearly the pixels per inch are going to be way different.
The TV's pixels are much bigger to cover that expanse and so has a lower ppi density.
The amount of pixels are the same it is just the ppi level is different.

At 300 DPI as a standard size of ink droplet is made up of many picoliters given that;
A picoliter is a trillionth (one millionth of a millionth, or 10 to the -12th power) of a liter, which can be represented numerically as 0.000000000001/liter.
The prefix pico denotes a trillionth part, just as the prefix nano denotes a billionth part.

Each printer though has it's own picolitre size.
I have the Canon Pro 100s which has a 3 picolitre droplet, other printers have smaller or larger.
This means my printer has to put down over thousands of picolitres per dot per inch.

Just to point out if you want to try and compare PPI to DPI then 300 dpi is 17.3205080757 x 17.3205080757
So draw a square one inch by one inch and put 17.3205080757 dots along the bottom edge & then 17.3205080757 dots along the side.
Now make that into a grid of squares (the dots) and you have your 300dpi one inch square.

You'll find most monitors are far higher than 300 dpi though.
Take this rubbish 22" with 1920x1080 pixel resolution I am currently using.
Along the bottom is 19 inches & the side is 10.5 inches
Giving approx 101 x 102 pixels per inch which is a crazy 10K pixels plus per inch.
But your 50" TV would be less pixels per inch of course even though the overall resolution is the same.

So PPI depends on the size of the screen.
But DPI is always the same it just depends how many picolitres your printer takes to fill up the space.

Until all printers state their PPI when printing there will always be this mis understanding that PPI is the same as DPI, please stop this as they are not the same.

 

[StewartR]

PPI & DPI are NOT the same thing, fact.....

Sorry, but much of what you've written is wrong. You are confusing linear inches with square inches.

 

[retrosi]

Sorry, but much of what you've written is wrong. You are confusing linear inches with square inches.

Maybe linear are different of course, however the basis of what I am saying is correct, PPI is screen related & DPI is not.
And if you take a linear dimension which I have as in the length of a monitor and then its side length that still gives you its pixels per inch.

At no point have I typed "Square inch" so please re read my post.
The only reference to being square inches is in my line stating and even then only in reference.

300 dpi is 17.3205080757 x 17.3205080757

However my main point of PPI is not the same as DPI stands correct.

I work at a printers and this has been the bane of our work for as long as I can remember.

 

[andyscott]

Just send it and print it.

Far to many variables such as printer rip and software, viewing distance, type of canvas etc and people's thoughts.

Remember billboards were printed of 4mp files from a d2h camera years ago.

 

[retrosi]

Just send it and print it.

Couldn't have put it better.
The headaches we get with explaining this to customers plus the questions we have to ask to get a sensible answer.

 

[StewartR]

However my main point of PPI is not the same as DPI stands correct.

That's true.

The problem is when you try to explain why they're not the same, because it shows that you don't understand it properly yourself.

Maybe linear are different of course

Maybe? MAYBE??? Surely you understand that linear measures (inches) and area measures (square inches) are fundamentally different.

At no point have I typed "Square inch" so please re read my post.

But that's the whole problem. You didn't use 'square inch' when you should have.

For example:

You'll find most monitors are far higher than 300 dpi though.
Take this rubbish 22" with 1920x1080 pixel resolution I am currently using.
Along the bottom is 19 inches & the side is 10.5 inches
Giving approx 101 x 102 pixels per inch which is a crazy 10K pixels plus per inch.

That's just nonsense. You've calculated the number of pixels per SQUARE inch (10k), and compared it with the number of dots per LINEAR inch.

For what it's worth most desktop computer monitors have resolutions of about 100 pixels per inch. That is far less than the 300 (approx) pixels per inch which most printers use, and it explains why images on monitors can appear pixellated if you look at them closely, but good prints don't.

Here's another example:

Just to point out if you want to try and compare PPI to DPI then 300 dpi is 17.3205080757 x 17.3205080757
So draw a square one inch by one inch and put 17.3205080757 dots along the bottom edge & then 17.3205080757 dots along the side.
Now make that into a grid of squares (the dots) and you have your 300dpi one inch square.

No, no, NO! Whether you're talking about DPI or PPI, it's always a measure per linear inch, not per square inch.


Your reasoning about picolitres is flawed too. I could explain it if you're interested, but it's complicated.


However, to close:

Until all printers state their PPI when printing there will always be this mis understanding that PPI is the same as DPI, please stop this as they are not the same.

Absolutely true!

 

[sk66]

Just send it and print it.

Far to many variables such as printer rip and software, viewing distance, type of canvas etc and people's thoughts.

Remember billboards were printed of 4mp files from a d2h camera years ago.

Agree 99%...

PPI and image size (LxW) are the same thing; you cannot change one without changing the other.

That is unless you resample (digitally manipulate) the image. Unless you spend good money on specialized software (i.e. Qimage) the results will probably be no better than what the printer's software will generate, possibly worse, and possibly no better even if you do use advanced resizing software.

The 300dpi "recommendation" is about matching the image ppi to the printer's dpi in order to get maximum IQ... some photo printers run as low as 240dpi, and the highest I am aware of currently is 360dpi (actual). It does not matter how many pixels you send, they will be printed at the printer's DPI capability.

The COC standard for "acceptable sharpness" requires less than 2MP for *any display/print size.* Yes, if you print 2MP large it will look like crap with your nose against it... but from any distance where you can actually see the entire image it will look fine.
The "COC standard" could be considered outdated/lax, but the max required would still be ~14MP equalling the max capability of the human eye (without very close viewing/scanning). IMO, way too much importance/emphasis is given to the "300dpi requirement."

 

[retrosi]

That's true.

The problem is when you try to explain why they're not the same, because it shows that you don't understand it properly yourself.

Maybe? MAYBE??? Surely you understand that linear measures (inches) and area measures (square inches) are fundamentally different.

But that's the whole problem. You didn't use 'square inch' when you should have.

For example:That's just nonsense. You've calculated the number of pixels per SQUARE inch (10k), and compared it with the number of dots per LINEAR inch.

For what it's worth most desktop computer monitors have resolutions of about 100 pixels per inch. That is far less than the 300 (approx) pixels per inch which most printers use, and it explains why images on monitors can appear pixellated if you look at them closely, but good prints don't.

Here's another example:No, no, NO! Whether you're talking about DPI or PPI, it's always a measure per linear inch, not per square inch.


Your reasoning about picolitres is flawed too. I could explain it if you're interested, but it's complicated.


However, to close:Absolutely true!

But still my point that PPI is not the same as DPI stands regardless of your being picky re squared or not.

 

[shapeshifter]

This been done to the death. All this business about 300ppi ect then you go and read up on it and it's all wrong.The conclusion is that as long as it's a biggish file it's OK. Otherwise how do posters ect get printed from 12mp cameras.Just use a big file. Until someone can show a simple explanation!
Some of this things like dpi,ppi,pixels,printer resolution get all mixed up along the way.Big file it's as easy as that.

 

[GHP]

It is all a bit confusing.
However, I have a couple of 20x16 prints taken with my old D70s, and they look fine !
Maybe it's magic.

 

[Box Brownie]

Most folk are talking about pictures seen at typical room sized viewing distances and subject to the printer indicating a target DPI setting such as 240 or 300 that is what to aim for.

However if you are talking posters seen in the street and seen from distances measured in 100's of feet away the DPI can be AFAIK very low possibly down to 80. I recall being told of a street sized poster being made from a Konica Minolta A1 bridge camera, 5MP sensor.