# Quesiton about printing quality and DPI



## fourwinds (Jan 30, 2012)

Hi there,

I had a question about printing quality and DPI.  I am making a photobook and wanted to have backgrounds to give it a scrapbook feel.  I pulled some backgrounds but when I put them into the program that I'm creating the photobook in it says the image quality is too low.  

The company recommends images of 300 DPI.  The backgrounds I have selected are 1280x1007 with apparently a horizontal and vertical dpi of 300 yet it still says the image quality is low.  The backgrounds I'm using are generally solid colours with a bit of texture (so no real hard lines) with the odd soft pattern such as the following:

Picaboo Free Backgrounds - View Entry
Picaboo Free Backgrounds - View Entry

Thoughts about quality when it's printed?  Will the background images show lots of pixels or do you think it should it be alright since they are softer and not as sharp as an actual photograph?

I've tried learning about DPI etc. but can't seem to wrap my head around it.

Any help would be appreciated, Thanks!


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## Rephargotohp (Jan 30, 2012)

Pixel Dimensions (2000 x 2000) don't have an inch in the to refer to, so DPI in that context is irrelevant. You need to relate DPI (or PPI for the PPI Nazis) to a document or in your case "page" size.
So say the book you are making is 10" by 10" or whatever it actually is. There's that inch word we need. So if you were making an image for the book that filled the whole page, You simply multiply the page size X 300DPI/PPI and that will give you the Pixel resolution you need to fill that page. In this case 3000 x 3000 (10 Inches x 300DPI/PPI)

If you are making an image that will appear on the page as 4" x 6" in actual size, then do the math again and you need at least 1200 x 1800


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## fourwinds (Jan 30, 2012)

The book I'm creating is 8.5 x 11

8.5x300 = 2550
11 x 300 = 3300

So to have a 300PPI I would need an image that is 2550 x 3300 in size?  I'm guessing my images are wayyy to low resolution then as they're only 1280x1007?

Thanks!


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## Rephargotohp (Jan 30, 2012)

Y^ep-, that's what you need. Sometimes background textures can be scaled ( enlarged) and still look OK, But it really depends on the quality they are too begin with.
You can try taking it and changing the image size in Photoshop, make the "Document" size 8.5 x 11 and 300 DPI under Image Resize, Then click View Print size and see how it looks on screen. If it looks pixelate, you may be out of luck with them


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## fourwinds (Jan 30, 2012)

Sorry for all the questions! 

So I don't need to actually go into photoshop and save the resized version - I'm doing this just to check if it looks pixelate? In my book I can just use the original picture?

 When I do take them into photoshop and go to "print size" it's not actually showing up as 8.5x11 on my monitor (assuming due to the program not knowing my resolution and size of my monitor) but the rulers do say it is that size; so if the images don't look too bad in the "print size" mode then they should theoretically look alright when printed?  

Thanks so much - you've been so helpful!


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## JG_Coleman (Jan 30, 2012)

fourwinds said:


> When I do take them into photoshop and go to "print size" it's not actually showing up as 8.5x11 on my monitor (assuming due to the program not knowing my resolution and size of my monitor) but the rulers do say it is that size; so if the images don't look too bad in the "print size" mode then they should theoretically look alright when printed?



The truth is that, until you actually print the image at 8.5 x 11, you won't really know what level of quality you're going to get.

Do you have a printer?  If so, just print a full-page, 8.5" x 11" copy of the image and see how it looks.  Most ordinary printers won't print to the very edge of the page, but they usually can print at least 8" x 10.5".  That'll be large enough to get an idea of the quality you're looking at.

The key point here is that, until you actually print an image, "DPI" and "PPI" are meaningless numbers.

For example, let's say you've got two images:

1) 3000px by 3000px at 100dpi
2) 3000px by 3000px at 300dpi

These images will look identical on a computer monitor.  The only difference is that, when you go to print them, image #1 will be 30" by 30".  Image #2 will print at 10" by 10".

EDIT
*****

Okay... "meaningless" wasn't the right word.  There are uses for knowing DPI/PPI before an image is printed... those reasons just don't really relate to your problem.


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## KenC (Jan 30, 2012)

I've printed lots of images below 300 ppi and they look fine.  I think the lowest I've gone is about 180 or 190, but I've read that others have been able to get good prints even lower.  Certainly anyone who's done a lot of printing will tell you that if you have at least 230-240 that would be just fine.


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## KmH (Jan 30, 2012)

Dots per inch (DPI), is no where near the same thing as pixels per inch (PPI). DPI refers to a printer's output resolution. PPI relates to the size of a print based on the photo's pixel dimensions.

Interchanging the 2 terms is like calling yellow - blue, or meters - miles. :lmao:

Getting a book printed you need also need to be concerned with LPI - Lines per inch.

It's like the fact that many people that should, don't understand that for any internal combustion engine that can rev high enough,  the torque and horsepower values are always exactly even at 5252 rpm.


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## Rephargotohp (Jan 30, 2012)

fourwinds said:


> Sorry for all the questions!
> 
> So I don't need to actually go into photoshop and save the resized version - I'm doing this just to check if it looks pixelate? In my book I can just use the original picture?
> 
> ...


You actually can calibrate Photoshop to show actual Prints size, By default it is set for a monitor resolution of 72PPI. however that's an old standard. Most are closer to 96PPI.

To calibrate Photoshop for print size, Measure the width of your monitor in inches, The check what resolution your Monitor is set to. So say iit's 1980 x 1200 Monitor.
Devide the 1980 by the inches, say 20" and you will get 99ppi as an example.

Then in Photoshop, Go to Edit> Prefrences > Unit and Rulers and under Screen resolution, Change it to what number you come up with. Now when you hit print size you will see it actual size

If you do save it, save it with a differnt file name so you don't ruin the original if you need it

If you went to a Offset Print company to make your book, you would need to worry about LPI, But almost all of the One off Book manufactueres (MPIX, Adorama, Bay, Blurb etc) have made it very simple for their users and you only need to be concerened with PPI for your page size

Also those book printers do not use the PPI listing of a file into play. As long as the Pixel x Pixel resolution is suffcient, you will be fine. The only time the document would print different sizes is if you just hit "Print" on your computer


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## Rephargotohp (Jan 30, 2012)

KenC said:


> I've printed lots of images below 300 ppi and they look fine. I think the lowest I've gone is about 180 or 190, but I've read that others have been able to get good prints even lower. Certainly anyone who's done a lot of printing will tell you that if you have at least 230-240 that would be just fine.



It depends what you are doing and your print companies requirements. For Digital C Prints most labs want 250PPI Optimum and 100PPI Minimum. However Books are Press printed not Photographic Process Printed and often require 300PPI


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## JG_Coleman (Jan 30, 2012)

KmH said:


> Interchanging the 2 terms is like calling yellow - blue, or meters - miles.
> 
> Dots per inch (DPI), is no where near the same thing as pixels per inch (PPI).



It's more like calling a tomato a vegetable, only to have somebody chime in and remind you that,"  No, no!  It's not technically a vegetable, but a fruit!"  And everyone rolls their eyes, sighs and says,"  Yes....yes... we know... thank you..."

In common parlance, DPI and PPI are routinely used interchangeably.  They shouldn't be... it IS technically incorrect...it IS improper... but it also ubiquitous.  Just go along with it LOL :mrgreen:


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## Big Mike (Jan 31, 2012)

JG_Coleman said:


> KmH said:
> 
> 
> > Interchanging the 2 terms is like calling yellow - blue, or meters - miles.
> ...


I'm with Keith on this one.  If we ignore it and 'just go with it'...the misinformation will just spread.


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## analog.universe (Jan 31, 2012)

This is a really good article about print resolution that may be relevant: How Big Can I Print by Thom Hogan


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## JG_Coleman (Jan 31, 2012)

Big Mike said:


> I'm with Keith on this one.  If we ignore it and 'just go with it'...the misinformation will just spread.



Well, I'm not saying that the distinction between DPI and PPI is meaningless.

For example, I would very much expect that a botanist conducting scientific research on genetically engineered tomatoes should have a very good understanding of why the tomato is technically a fruit.  But the ordinary person who isn't nearly so involved in such things can call a tomato a fruit or vegetable, and it really makes no difference.

The idea is simply that a "pixel" is oftentimes thought of as a "dot".  It's an entirely understandable way of looking at things.  A pixel is, indeed, a "dot" in a sense.  In the case of PPI and DPI, the conflict simply arises because, in terms of printers, a "dot" has a very specific definition.  But, just as the ordinary person can harmlessly call a tomato a vegetable, so too can the casual photographer interchange DPI and PPI without any problems.  If the OP plans to buy a nice photo printer and start running off 13" x 19" fine art prints... then yes, it would be most beneficial to understand the technical differences between DPI and PPI.  Until then, it doesn't really matter.  Windows, for example, refers to the metadata "PPI" of an image as "DPI" in image properties.  Many photo printing services also specify their minimum pixels-per-inch for a print as a "minimum DPI".

Like I said... it IS technically incorrect...  but it's also systematized in that fashion all over the place.  And I, for one, have no burning desire to get the world to start calling a tomato a fruit.  It is a vegetable... end of story.


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## Big Mike (Jan 31, 2012)

I get what you're saying...

But my point was that if we don't correct the problem when we see it, the person who has is wrong, might tell someone else.  Or someone will view the thread on this forum, and think that it's correct, simply because it's on a photography forum.  

And yes, the difference here is pretty innocuous...but it could lead someone to make mistakes down the road.


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## KmH (Jan 31, 2012)

Photoshop consistantly makes the distinction between PPI and DPI, always referring to input resolution (cameras, scanners) in PPI or PPC, and output resolution (printers) as DPI.


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## fourwinds (Jan 31, 2012)

Thanks for all the information!

I did try printing the backgrounds out on 8.5x11 paper as well as looking at my backgrounds in photoshop and they don't look bad considering most of them are just soft textures. 

I think I'll try using them and hope for the best

I learned a lot, thanks again!


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