I have a couple Questions for Artists on the forum.

[Andy847]

Hi everyone, I'm a guy who loves Drawing for a hobby. I've posted some of my pics in the Ipad forum here and I'm working on an IPP 12.9" with the Apple Pencil. I had someone ask me to do a portrait of their dog and did it for them, but having a problem with something. I had a buddy who works for Xerox Print the drawing out in color on the machines he works on. It was a big size 14" x 20", which I think is bigger than I want to go, but wanted to see what it looked like. I did the portrait in Procreate, so when it printed out, it became a little Pixelated in parts. Which leads me to my Questions. I usually draw in Procreate, which I know is the best, but maybe not for what I'm trying to do.

1. If I want to eventually do prints of My Drawings, should I be using Apps that draw with Pixels or Vectors?

2. What is your Method of reproducing your Digital Drawings to a Print?

I would like to keep using Procreate, as I love the program much more than say Adobe Draw. I think if I still stay with Pixelated drawing apps, I can maybe go 8" x 10" as the largest and see how that turns out. I just think the size I did before was too large. I have done a drawing in Adobe draw, just a black line drawing. I'm familiar with CAD which I went to school for, so have worked with Vectors before. Thanks in advance for any advice.

 

[Pakaku]

If you were working in Photoshop and intended to print, you would need to specify the "Dots Per Inch" depending on the printer. 300 DPI is the general minimum for an acceptable print, so a document that was printed at 14"x20" would have to be at least 4200 x 6000 pixels. Procreate doesn't work with DPI as far as I know, but you do specify the canvas size in pixels anyways, so the math still applies. If your canvas is smaller or if the DPI needs to be higher, your pixels will become bigger and more noticeable at the same print size.

 

[bent christian]

Minimum dots per inch (DPI) is defined as Linescreeen (LPI) multiplied by 2. Most digital printers output at at 133 LPI (266 DPI min) or 150 LPI (300 DPI min). 300 DPI is suggested to cover all bases, but it might not be necessary. Digital printers are far more forgiving of low-res art than a plated press will be, so you can actually go a little lower and not show pixillation. But, set your document to the correct resolution to begin with, always.

If you can do your art in a vector format, this would be best, as you can scale to whatever size you want without a loss of resolution. If raster is your only option, yes, do the math and set your document to the correct resolution. Many applications will use PPI and DPI interchangeably. This may cause some confusion. Photoshop and some other applications will give you to equivalent DPI/PPI as you enter the pixel dimensions.

 

[organicCPU]

133 LPI (266 DPI min) or 150 LPI (300 DPI min)

To find out the needed DPI you should count with a quality factor between 1.5 and 2. In your example 266 DPI min should be written 266 DPI max. Minimum needed DPI is around 200 DPI for 133 LPI. The quality factor can vary. Sometimes a minimum is 1.4, some machines have best results with 2.1. If you can afford the file size, as a rule of thumb factor 2 gives you excellent results, but is not the minimum you need.
For high quality Fine Arts Prints there could be benefits in using around 400 DPI while there is usually no need to go beyond 72 DPI for Large Format Printing. It depends not only on reproducible quality, but also on the use case and on additional prepress steps like reasonable sharpening and experienced color separation to get the best results. The common thing is to work with 300 DPI, the best is to work together with a good printing company that understands your aims and will give you the details for the specific chosen production technology.
Even if someone did the best he could do with the file for a specified purpose, if it comes to production, a cheap online service for the average consumer needs could destroy every intentionally aspect of an artist's work...or generate an unreproducible unique style.

 

[Andy847]

Well, thanks everyone for replying and totally confusing me. LOL. I ended up looking online and at different DPI for the size I'm looking to print. One website gave a chart and explained the math somewhat, but I usually make my drawing's canvas the size of the Ipad Pro screen size, which when I did the math, 200 DPI would be good for the 8" x 10" size I'm looking for. Now I'm taking it that from what I read, Just make sure the canvas is big enough in pixels for the largest size I want to print. Then it also depends on the Printer and I can adjust the DPI as I want to achieve the maximum print size for the Canvas. I'm taking it that the DPI can be changed in the printing process, as long as the canvas size is big enough to accommodate the maximum size I want to print at. Am I correct? You take the Height and Width of the canvas in pixels and divide by the DPI I want to use. I just chose 200DPI, since it was easy to divide by and was listed on the chart along with 300DPI in the example I seen online. It also allowed me to do an 8 x 10 print easily.

 

[organicCPU]

I'm taking it that the DPI can be changed in the printing process, as long as the canvas size is big enough to accommodate the maximum size I want to print at. Am I correct?

It can be changed, but if it will be changed during the printing process, that is always the question. I wouldn't want a printing service to do so, but some folks shooting 72 dpi photographs would get sad if it won't be changed. If nothing will get changed, you can control the result much more.

 

[bent christian]

To find out the needed DPI you should count with a quality factor between 1.5 and 2. In your example 266 DPI min should be written 266 DPI max. Minimum needed DPI is around 200 DPI for 133 LPI. The quality factor can vary. Sometimes a minimum is 1.4, some machines have best results with 2.1. If you can afford the file size, as a rule of thumb factor 2 gives you excellent results, but is not the minimum you need.
For high quality Fine Arts Prints there could be benefits in using around 400 DPI while there is usually no need to go beyond 72 DPI for Large Format Printing. It depends not only on reproducible quality, but also on the use case and on additional prepress steps like reasonable sharpening and experienced color separation to get the best results. The common thing is to work with 300 DPI, the best is to work together with a good printing company that understands your aims and will give you the details for the specific chosen production technology.
Even if someone did the best he could do with the file for a specified purpose, if it comes to production, a cheap online service for the average consumer needs could destroy every intentionally aspect of an artist's work...or generate an unreproducible unique style.

As a professional in the industry, I think it would be irresponsible to tell artists and designers who don't understand production (which is most of them) and have no access to the output device for proofing that minimum resolution should be LPI x 1.5. My experience tells me that when you open the door to what is possible (but not certain) on the low end, they get themselves into trouble. Artists and designers should consider minimum resolution in most print situations as DPI = LPI x 2. Of course, sometimes this might need to go higher depending on the output device. If you run into a situation where an image is lower than that and no other option exists, OK, it might be fine. Don't assume you can get away with it always. When an artist has created a raster graphic, often there is no going back. As a technician, I have to assume the worst and always overcompensate.
[doublepost=1474552979][/doublepost]

Well, thanks everyone for replying and totally confusing me. LOL. I ended up looking online and at different DPI for the size I'm looking to print. One website gave a chart and explained the math somewhat, but I usually make my drawing's canvas the size of the Ipad Pro screen size, which when I did the math, 200 DPI would be good for the 8" x 10" size I'm looking for. Now I'm taking it that from what I read, Just make sure the canvas is big enough in pixels for the largest size I want to print. Then it also depends on the Printer and I can adjust the DPI as I want to achieve the maximum print size for the Canvas. I'm taking it that the DPI can be changed in the printing process, as long as the canvas size is big enough to accommodate the maximum size I want to print at. Am I correct? You take the Height and Width of the canvas in pixels and divide by the DPI I want to use. I just chose 200DPI, since it was easy to divide by and was listed on the chart along with 300DPI in the example I seen online. It also allowed me to do an 8 x 10 print easily.

I think you are taking a huge risk spending time creating a raster graphic that will print at 200 DPI. Minimum DPI is defined by the specific output device, not by a formula you found on the Internet. These equations are only guides. Never assume, always over compensate. I would recommend that you create your graphics at a 300 DPI pixel equivalent to be safe. There is no extra work involved, file size difference is likely minimal, and what if some day you want it printed on another higher quality device?

 

[organicCPU]

As a professional in the industry, I think it would be irresponsible to tell artists...

I totally agree. Sorry for misguiding with too much theoretical blah blah. I just wanted to make clear, that quality factor 2 isn't the required minimum in general, because that's not right. That doesn't mean you're wrong in recommending 300 dpi. I also wrote that 300 dpi is common, because it is simply working for most use cases and everyone without a background in (pre)press should use 300 dpi for raster graphics.
As a technician, you'll agree that dpi is one aspect of a good result, but not the only one...

 

[Andy847]

Okay, now I'm thoroughly confused. I'm pretty happy with using Procreate. I know that I usually do my drawings on a canvas size the screen size of my IPad Pro 12.9 which is 2,732 x 2,048px. So how does one figure out the LPI on the Canvas? Where does it say in Procreate how many LPI a canvas has? This is nothing like I expected and quite honestly very intimidating to me the more you guys tell me. If I knew how to figure it out, is there some kind of formula to use to get either LPI or DPI for Printing or does it go Way beyond that. I would be appreciative if someone could give me a direction on where to look to learn this or find this online. Thanks.

 

[bent christian]

So how does one figure out the LPI on the Canvas?

You don't. LPI relates to the lines per inch of the output device. Make everything the pixel equivalent of 300 PPI and you won't have to worry about anything more.

 

[organicCPU]

As I opened the pandora box I feel guilty to deliver more theory to answer the question (sorry bent christian):

Besides all further explanation I think you should work with the maximum possible amount of pixels that your workflow allows without any inconvenience. Often you don't know from the beginning what size you'll need later on, especially if you don't work for a special purpose. Besides the abilities of your software and hardware, you should consider the size of a single file, too. Over years that has been changing and will continue to change. So you'll have to reevaluate this.

If I knew how to figure it out, is there some kind of formula to use to get either LPI or DPI for Printing or does it go Way beyond that. I would be appreciative if someone could give me a direction on where to look to learn this or find this online.

Formulas simplified and from the technical view probably imperfect:

a (pixels) / x (dpi) = z (inches)
a: the number of pixels -> width or height of your raster image defined in your image editor
x: the amount of dots per inch (dpi) you'll set in your image editor -> 300 dpi fits most use cases for printing (for quadratic pixels equal to pixels per inch (ppi))
z: the size in inches for your final print

If you want to know, how much pixel you'll need at least:
(bent christian and me don't recommend this to anyone that doesn't know exactly what he does)

x (dpi) = y (quality factor) * z (lpi)
x: resolution dots per inch
y: always use 2 for quality factor if you don't know exactly what you're doing! In reality you could have values between about 1.5 and 2 though.
z: the resolution the printer is using in lines per inch. Ask your printing company or take 150 lpi as a value that will give 300 dpi as the result.

For your szenario 2732 x 2048 px are too less for your 20" x 14" print if you want crispy clear quality from a closer look!

The sizes you could print:
high quality: 2732 x 2048 px -> 9.11" x 6.83" (300 dpi)
don't use it, but minimum acceptable quality: 2732 x 2048 px -> 12.14" x 9.1" (minimum quality factor 1.5 for 150 lpi -> 225 dpi)

The pixels you would need:
high quality: 20" x 14" -> 6000 x 4200 px (300 dpi)
don't use it, but minimum acceptable quality: 20" x 14" -> 4500 x 3150 px (minimum quality factor 1.5 for 150 lpi -> 225 dpi)

A specific calculator that considers everything I don't know. Formerly some Macs were bundled with the Art Directors Tollkit. You could also use an image editor like Gimp or this pixelcalculator that are covering the basics.

Further online reading:
ppi: https://en.wikipedia.org/wiki/Pixel_density
dpi: https://en.wikipedia.org/wiki/Dots_per_inch
lpi: https://en.wikipedia.org/wiki/Lines_per_inch
halftone: https://en.wikipedia.org/wiki/Halftone

 

[paulryp]

All of the math on this thread is nonsense. Just set up an A4 in photoshop at 300 dpi and scale up if you need bigger. Its not difficult or anywhere near as complicated as everyones making out. Most epsons print at 220 dpi so an A4 at 300 would scale pretty well to A3.

 

[organicCPU]

All of the math on this thread is nonsense.

Can you explain where you can see an error and correct me, please?
Edit: Yes, it's mathematically wrong to put pixels on a level with dots and dots with lines, but that's the simplification I'm talking about. If you've got insights that will help to improve the answer, it would really be great to share that knowledge with us.

 

[chaosbunny]

Just set your canvas to 6000x4000 pixels at 300 dpi, this way you can print anything later and even do crops if you want to. Better to draw much bigger than you need it, this way you have all options later.

 

[inkstasy]

Hey I signed up just so I could answer this question - I am a 16 year vet photo retoucher and digital artist. I have tried to explain resolution to lay people a lot. I found the best thing to do is not confuse people with all the math, in that I agree with paulryp. It's really too much to worry about.
MY best basic non confusing advice is this:

Make everything you create in pixel format at 300 dpi @100%

I usually do things at 400 dpi but that's because I can make and handle files that are 3 or 4 GBs with multiple layers as my digital art is very intensive with a lot of details.
In your case I would just use the 300 dpi formula and you should be stellar for most purposes
ie; create your docs this way
8x10 @ 300dpi
18x20 @ 300 dpi
etc etc
If you want them around for possible different usages, I would build the files bigger than you may need just in case.
I'd be happy to explain in more detail but that's really all you need to know.
Things will print fine and you won't have to depend on anyone else needing to decide your resolution.
Also while vector may be scaleable with no res loss it has a much different look than a pixel based art form which can mimic most traditional media very well. Vector (unless you're quite advanced - maintains a more graphic style to it.
Hope this helps.

 

[organicCPU]

Make everything you create in pixel format at 300 dpi @100%

Yes!

My intention is not to confuse someone! The OP has asked for a formula in #9 and I tried my best to answer him. I think, that math is far far away from being perfect and nothing that considers or answers everything, but however it is helping me in the following situations:
1. If I need to calculate measures by myself, because the app only knows about pixels, like many renderers
2. To know how far I can go – means, what is the maximum size, that I'm able to print before I...
3. ...decide whether or not and how to upscale an image for printing

It's interesting for the OP to know how far one can go, too. He wrote, he usually did drawings with 2,732 x 2,048 px and was disappointed in the result of a 20" * 14" print. In my opinion, that's a completely different situation to someone who asks 'How am I doing right from the beginning?', because the OP already might have done a bunch of work. I think it's best for him, to keep his originals in the size he created them, to proper upscale a copy in case needed for a larger output size and to think about changing his workflow for future works. That's why I believe, the universal 300 dpi rule is not enough to know about for the OP, especially if you take his former work into account.

 

[ifman]

In Procreate on your iPad, create a new canvas using the "New Canvas" option at the bottom. Do not use the preset canvas sizes that are above. Under "New Canvas" you can set pixel size and set to 300dpi or higher. On a side note: the number of layers available to you in Procreate will decrease with image and dpi size....due to iPad limitations.

 

[dwig]

The resolutions terms used on many of these posts are incorrect and add a bit of confusion.

Digital images only have pixels. They can be tagged with a scaling factor that in effect says "hey, if you're a printing application that has the concept of a virtual page then scale this image so that x number of pixels fit 1 inch". This is the Pixels Per Inch (PPI) seen in Ps (yes, Ps has used the wrong term, DPI, for the last quarter of a century, but that doesn't make it correct).

Printers make dots. They have a printing resolution in Dots Per Inch (DPI). This is not related to a digital file's PPI.

Legacy offset printing uses some form of screen to break up the ink to effectively the impression of a lighter tone by revealing some white paper between the spots of ink. Classically, this is done with an Elliptical Dot Halftone Screen. These screens vary in what frequency of dots they produce and that frequency is marked with the term Line Per Inch (LPI). There are some rather interesting (if you're into the math) interference factors that arise when a digital file is processed to simulate a halftone pattern for such printing. If the digital file is either lower or higher resolution than an optimal value then the final prints loose sharpness. The formula is LPI * 1.5 = PPI. If you are printing on an offset press then this is important. If printing on an inkjet printer, ignore it.

I regularly (as in 2-5 prints per day at sizes 20"x30" to 40"x96") print digital images. Our printers have a DPI resolution of 1440. As a norm, I send the printers digital files that are 300PPI at the final print size. That last bit is critical. It means that a file for printing a 20"x30" print is 6000px x 9000px. An iPad file that is 2732x2048px is only about 140ppi when scaled up to be printed in the 20"x14" range no matter what PPI with which you tag that original iPad file.

What I print are photographic images, and they can be upsampled quite successfully. Digital drawings and some "paintings" don't always upsample successfully as the eye/brain often expects much more of a sharp edge on many of the elements in the work.

 

[organicCPU]

Printers make dots. They have a printing resolution in Dots Per Inch (DPI). This is not related to a digital file's PPI.

The formula is LPI * 1.5 = PPI.

Hello dwig and welcome to the club of people confusing others ;-)
I believe you know exactly what you're doing and you do it probably right! Please don't blame me too much for a little criticism!
You write in one sentence that dpi is not related to ppi and in another sentence you explain a formula (that actually works) where you make a relation between lpi (line [of dots] per inch) and ppi -> joining the club!
I'm not the master of all printing, but really seriously interested in the topic, that's why I reply!

Legacy offset printing uses some form of screen to break up the ink to effectively the impression of a lighter tone by revealing some white paper between the spots of ink. Classically, this is done with an Elliptical Dot Halftone Screen. These screens vary in what frequency of dots they produce and that frequency is marked with the term Line Per Inch (LPI).

That's not wrong, but I think it's too generally spoken and can be confusing, too! I'd like to confuse a bit more ;-)
I'm not sure what you mean with "Legacy offset printing", because offset printing in general isn't really legacy just because there are other digital printing techniques.
I'd say from the perspective of today legacy offset printing is the conventional offset printing with an AM (amplitude modification) halftone screening, even though still used. With an AM raster your dots sizes varies based on the tonal values, not only the frequency of dots is changing. If you consider the way the halftone screen is generated, I think that for example a round or diamond dot shape is as classical as an elliptical dot shape.
Then came up strict FM (frequency modulation) screening around Y2K, where the size of a dot is/was fixed, but very small compared to AM. Closer placed dots gave darker colors and wider placed dots brighter ones. The next steps were parallel developments and I don't know what was first. The hybrid screening (some call it cross modulated XM screening) combined AM and FM, means variable dot size from very small to large. That XM screening was immediately combined with more complex mathematical algorithms in the Raster Image Processor (RIP) resulting in stochastic screening. In stochastic printing any kind of shape of the dot is combined including round, elliptical or diamond like shape. That is also known as a FM staccato (stochastic) raster. All techniques are used for different purposes. Maybe the strict FM screening was a necessary step and is not used so much anymore, because of more advanced technology that incorporated this method. The transition from AM to FM screening was made possible with the help of powerful computers and the computer-to-plate (CTP) technology. It just didn't make sense to expose an analog film with such small dots a FM screen can have and transfer it afterwards back to a plate. Direct transfer to a plate without a film made this possible.
And here it comes: These modern offset printing machines in reality have multiple times the dots per inch on their plates as your or my formulas are able to proper calculate. That's why we are confusing people, especially those that know a bit of what is going on. But why are we then confusing? We want to help! Ooops, that confuses me!
Why are our formulas useful?
We have at least the additional factors human and the printing material to take into account. For an explanation of the human factor and how we see image detail and sharpness, I've found Norman Koren's website useful. For the factor printing material I couldn't really find a comprehensive site but here is a small chart in the middle of the page that is freely available in an American Printer article where one can find some guide values of what lpi to use for different kind of papers. And that's where the formulas we gave are coming together.
Printing machines might evolve fast, but materials for printing not so much (except our Mac's nice retina ePaper displays). There is a limit of the dots that make sense to print on a paper. The cheapest magazine paper can show more dots like a high quality newspaper paper and then imagine what happens if you print on wood or toilet paper. If I say to ask the man at the printer or in the printing shop, I mean that this is the only one who knows the machine, but also the only one that knows the surface you're printing on. And that is the limiting factor for offset, inkjet or whatever printing. If you ask, some will give you a dpi, some a lpi, some a l/cm. And then you can take a formula and get your PPI (long time incorrect named DPI in Photoshop). That ppi will feed the printers RIP with the minimal needed or maximal useful amount of different color information to make the selected output device print a nice image for you on the material you've chosen.
I've found this website on a DePaul University server useful and easy to understand, but there are also more or less expensive books on the web.

Sorry, dwig, I guess you know all this and may think, that I'm a confusing fool to tell you all this. In reality I'm writing this, to get more confusing answers from people that know something else about it and want to share their knowledge.

If printing on an inkjet printer, ignore it.

What is so different for inkjet printing then?