DPI setting

[timibaltazar]

Hi... Anyone know how to set potoshop setting (in pop up when your starting to draw) to DPI? It's always on ppi and there's no option in drop down menu to dpi. Thanks

[davescm · Accepted solution]

Hi

Dots per inch (DPI) is a printer function and has no place in Photoshop. It refers to the dots that make up pixels or a printing screen (lines per inch LPI).

Pixels per inch (PPI) is used in Photoshop to convert pixels into real world measurements (cm or inches) prior to print output.

Dave

[timibaltazar]

I'm confused... So, when they say submit an artwork that's 1280x1280 with 200dpi... I don't really need to change the resolution setting in photoshop (when opening a new file)? I just go draw with a 1280x1280 with 200ppi setting?

Sorry I don't really understand, tried researching but ended up more confused.

[davescm]

Yes they are using the wrong terminology. Just send with 200ppi and you will be fine.

Dave

[Chuck Uebele]

Pretty much. PPI and DPI often get used interchangeably. Most often if someone tells you they need an image 300dpi, they really mean PPI. As Dave said, dpi is just a printing measurement and really has no relation to your file.

[jane-e]

timibaltazar  wrote

Sorry I don't really understand, tried researching but ended up more confused.

The reason that your research has confused you is because a lot of people get this wrong and then post misinformation. Adobe Photoshop has it right, and you are getting accurate information from all of the professionals who have been responding.

P stands for Pixels; D stands for Dots. You have larger or smaller pixels, and if you zoom way in you can actually count how many pixels are in an inch (ppi).

You get dots when you have ink on paper (dots per inch). The old dot matrix printers were 72 dpi, and you could see the choppiness with the naked eye. At 300 dpi, you may not notice until you hold a magnifying glass up to text on a printed page, then you will see jaggies. Then hold a magnifying glass up to text on a professional magazine. You won’t see any jaggies because it has more dots of ink per inch, or dpi.

It doesn’t even make sense the other way, so you have to wonder why people get it wrong.

[gener7]

Digital Images are composed of Pixels. Hence PPI to describe resolution.

DPI is device resolution and is not always the same as PPI 

Take Inkjet Printers for example. An Epson Stylus Photo is 5760 DPI x 1440 DPI, but the ideal digital image resolution for it is 1440/4 which is 360 PPI, not 5760 or 1440.

Yes, in earlier days, some instructors and textbooks used DPI to describe digital images, but that has been cleared up for the most part.

300 PPI is a good starting point. I don't think you would notice much difference.

[JJMack]

I do not care if one uses PPI or DPI for Displays or Printers For Printers its Print Pixel Size nothing to do with dots. Its the Image Print Resolution its Pixel density.    Pixels  printed by INK jet are painted in using many tiny droplets of different color inks to paint the correct size and color pixel.    300DPI means  the pixels are 1/300"x1/300" the are 90,000 pixels per square inch.     PPI is used by Photoshop to calculate how many pixel to work on when you use a command and use a unit like 1".  It does matter which term you use its pixel Density why not use PD.

Displays do not play the resolution game they can not change their spots they have one resolution and  it can not be changed.  To change the size an image display on a display you scaling the image  Photoshop zooming.   The size an image display on a display depends on how many pixels pixels the image has and the display's Pixel size its resolution not the image resolution.   An image is displayed on a display with the displays resolution not the image resolution.   A image will display a different size on different resolution displays. Is it a 24" 4K image  or a 65" 4k image. It depends on the displays resolution

An image Pixel Density is very import and it matters. Even though displays do not participate  in the game.

[timibaltazar]

Thank you guys for answering.

So basically, it's 2 different units that are not interchangeable because ppi is for designing and dpi is for printing.

Thank you so much again, really appreciate the help.

[Eugene Tyson]

Yeh to be honest, it grinds my gears when someone says DPI and PPI aren't interchangeable, it's definitely interchangeable in the apps provided, it's a direct translation.

It's the internet police that go to town on the do-gooders who accidentaly say dpi and ppi in lax situations. It's essentially the same thing, yes DPI is print and PPI is print, but it's the same thing essentially. I know someone will come along and give me a very technical run down, but I don't care.

Nobody ever mentions LPI!

It always gets lost in these conversations!

While stictly 300 is a good guess at the ppi required it actually depends a lot on the image subject, printing method and a few other variables. Typically 300 ppi is a good rule of thumb. If it's a grayscale image you can probably go about 1/3 of that.
A foggy image you could probably go about half that
Anything with little definitition is about half that too.
For printing on litho machines plates are made with lines per inch (LPI) and these LPI are key key to printing resolution.
Newspapers are pourous and have a typical LPI of 80-100
Magazines or low quality magazines have a typical lpi of 100-150
Magazines mid-high end have a LPI of about 150-175
And High End coffee table/art type books typically have a LPI of 175-200The rule of thumb most people go through is that that the LPI must be x2 to get the optimal PPI for printing (or DPI in print)This is where the 300PPI rule of thumb comes from, as most printers set their LPI to approx 150 for most jobs and 150 x 2 = 300.
But that's a bit of misnomer in terms of the figure - as the x2 rule is erroneous. The actual figure you should multiply by is 1.41 (recipricol)
This is due to the halftone dots in questions, which are printed in a square shape. During the process the halftone square needs to be rotated 45 degress to avoid Screen Clashes called Moire (http://the-print-guide.blogspot.com/2009/12/moire.html)
It's 45 degrees because technically that's all a computer algorithim can do - it can faux rotate at 15/30/45/60/90 etc. but in technical computer terms 45 degrees is the only true rotation for very techincal reasons.
When you rotate a square 45 degrees it's now exactly 1.411111 times the size it was from horizontal cross Say when the square is square shape and it's 1 across the top, and 1 down the side.

When it's rotated 45 degrees it's now 1.41 from tip to tip.
And that's why you multiply the LPI of the print by 1.41 to get the true DPI (PPI) for placing your images.

Digital printing is completely different process, it doesn't use plating or halftones, it uses toner (powder) and electrically charges the paper in the places the powder sticks to.

In essence, it's a lot more forgiving than lithographic printing and you could go as low as 150-200 - but you would have to check that with your print provider.

[timibaltazar]

I'm really bad at this. Let me just get back to my original question.

If someone ask me to provide a 1280px X 1280px with 200DPI, can I use this (refer to attach picture) setting even though photoshop says it's in PPI?

Sorry I'm really not a technical person so any help is much appreciated.

[davescm]

Simple answer - yes

Dave

[davescm]

Hi

https://forums.adobe.com/people/Eugene+Tyson  wrote

Yeh to be honest, it grinds my gears when someone says DPI and PPI aren't interchangeable, it's definitely interchangeable in the apps provided, it's a direct translation.

They are often used interchangably but that can occasionally lead to confusion as in the example of inkjet printing shown by Gene in post 5 or as the original poster found when raising the question.

https://forums.adobe.com/people/Eugene+Tyson  wrote

Nobody ever mentions LPI!

See post 1

Dave

[D Fosse]

Let's not muddy the waters, please, Eugene...while there's a semantic case for all these reservations it doesn't help the OP. He asked a straightforward question about what the difference is, and got perfectly stringent and logical answers to that.

If you personally think DPI and PPI should be interchangeable, I suppose that's your privilege and I won't argue. But I bet it has confused the OP no end.

[Eugene Tyson]

Dont think it has. Dpi for print. ppi for screen.

Straightforward.

When going to print it will be 300 ppi on screen and 300 dpi in print.

Nothing confusing about that. All this nonsense and superiority when claiming to know the difference between dpi and ppi should really stop.

I explained excellently how it works. No nonsense.

[Norman Sanders]

I posted this message several months ago and it may be helpful here.

***

To create constancy and eliminate the current confusion in definitions, I would like of offer a standard regarding terms for use in all Forum posts. They refer to dpi, lpi and white balance. If I am lucky, in the future these terms will be as universally treasured as the flag, home and the loyalty of a fine dog. 

PPI: Pixels – picture elements per inch viewed on a monitor. I think we are safe here.

DPI: The number of inkjet printer ink droplets. It is measured in picoliters and may appear among a given machine’s specs. When printing, the number of droplets varies throughout the tonal scale with few ink dots deposited on a surface to create the lighter tones and more of them deposited to create the darker tones. We might refer to this variation in the number of dots as Frequency Modulation (FM) and it is the only time the term DPI should be used. Promise me.

LPI:  Dots deposited on a surface by offset lithography or letterpress printing. When viewed from a distance, the dots seem to fuse and create a smooth gradation of tones. On the printed page smaller dots create the lighter tones and larger ones create darker tones, but the number of dots throughout does not vary. Only dot size varies. We might refer to this as Amplitude Modulation (AM). 

Why LPI?

Some halftone history: Before the introduction of computers in the graphic arts, the device used to create halftones consisted of two sheets of glass, each with fine parallel opaque black lines -- perhaps 150lpi – glued together (one vertical, the other horizontal) to create a grid of small clear windows. When this device, called a glass halftone screen, was positioned in front of high contrast film (not in contact with the film) in a camera and exposed to an image, it broke the light reflected from the subject being photographed into an array of various sized dots -- a halftone negative that was then used in plate-making.

Today, glass screens and their successor -- plastic contact screens of a checkerboard-like design (which are placed in contact with the film) are gone but the term lines-per-inch (lpi) -- a vestige of the glass halftone screen era -- remains to designate the number of dots to the linear inch in the image on the printed page. That is why a 150 dots-to-the-linear-inch image on a printed sheet, for example, is referred to as a "150 line halftone." To repeat: a halftone is an example of Amplitude Modulation (AM), different from an inkjet’s FM.

Now, on to White Balance (and don’t even try to talk me out of this) is defined as the neutral quality of only the highlight values in an image. The neutral quality of tone elsewhere in an image -- sidewalk, schnauzer, slate roof -- should rightly referred to as Gray Balance. These are not two arbitrary definitions: they are terms that have been used in the graphic arts for about a century. The camera manuals are wrong. There. I said it and I'm glad.

If you concur, raise your hand.

[davescm]

Thanks Norman - that is a great summary, and I will raise my hand and buy in to that.

As a practical example my Epson printer uses up to 2880 x 1440 dpi (up to 4,147,200 dots) to print a 1 inch square image at 360 ppi (129600 pixels). So that is up to 32 dots, or droplets, for each pixel.

Dave

[JJMack]

No I do not agree with what your what you wrote about Displays or Printers.  PPI yes a display has one that can not net changed  manufactures also use  terms like 1080p resolution and 4k resolution which is not resolution at all it number of Pixels. A display has one PPI so any image resolution settings is meaningless for a display it can only use its ppi resolution.

DPI on a printer has nothing to do with number of droplet or even the image resolution.  Its a Print quality setting as to how well Pixels should be  painted in.   Higher quality settings can not be used on plain paper for to many droplets of ink will be use to paint higher quality pixels the paper will be coated with to much ink and be soggy.  Yes the number of droplet use will change with Printers DPI setting. However the numbers of droplets used is more a printer technology thing different printers use different  ways to produce droplets and control their size.   No matter what Printer DPI setting you use the Printer will Paint Pixels the size the Image resolution  is set to If an image has a 300 DPI setting and you set the printers  DPI setting to 2880dpi   Pixels will be painter 1/300"x1/300" the Image Print resolutuin the print will have the correct image resolution and the pixels will have the highest quality the printer can produce.

In general user do not get the right discoinnects because the way terms are used. It is very confusing for most.

I also do not disagree with what you wrote.  Its all part of the story.

[Derek Cross]

And don't forget to mention intaglio printing Norman.

[timibaltazar]

Alright, I think I have the general idea on how I should do it.

Thanks again for being helpful guys.

[D Fosse]

timibaltazar  wrote

I think I have the general idea on how I should do it.

Go forth and do Good Work After a while all this becomes second nature. I still maintain that there's a high degree of semantics involved in this, which is why these discussions tend to go on forever, like a medieval scholastic dispute. How many angels can perform a square dance inside of a pixel?

It might be easier if you just read it literally: pixels per inch. You have so many pixels in your file, and so many inches of paper in front of you. The rest is math.

[jane-e]

To close the thread, please mark one answer correct. You certainly got more info than you needed!