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DPI, size. PNGs

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Stormy Conner

New Member
I thought I understood DPI and what was needed for printing, but for some reason this job I am working on is making me feel like I don't. We are just going to print these baseball signs for a school and the design was done by someone else. When I got them I brought them up in Photoshop and checked the size and resolution like my boss asked me to. The actual size in inches was fine but they were 72 DPI. I thought I was 100% sure that it needed to be 300 DPI to print good, 150 at the absolute minimum. And I know that things on screen look way different than what would actually print. I just kinda want to be sure that I do understand this. According to Photoshop under image size the .png they sent is 62.5" x 100" at 72 DPI. PNG's are for website and such right? I am not as familiar with them as I am others file types.

UPDATE: Thank you everyone for all your help. I ended up using Photoshop to lower the size and up the resolution and everything is looking good. I guess I really didn't understand images like I thought. I have been too spoiled by vector art lately. LOL
 
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Solventinkjet

Solventinkjet

DIY Printer Fixing Guide
PNGs are for websites but not uncommon to get from customers who don't know any better. As long as the original design was made at 1:1 scale at 72dpi, it should look fine from normal viewing distances.

Also, when in doubt, crop a smaller section from the image and print it. See how it will print and decide from there.
 
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Stormy Conner

New Member
Solventinkjet said:
PNGs are for websites but not uncommon to get from customers who don't know any better. As long as the original design was made at 1:1 scale at 72dpi, it should look fine from normal viewing distances.

Also, when in doubt, crop a smaller section from the image and print it. See how it will print and decide from there.
Click to expand...
I feel like though that as a designer if I am starting with a digital photograph to turn it into a poster for the proud parents of baseball players that I wouldn't lower the quality of the photo. Why go from a 300 DPI digital photo to a 72 DPI poster. I printed a small section of it and am not impressed. Looks wrong. Hopefully the designer is able to send me a higher quality version. They did a good job on the look of it incorporating the baseball picture with a cool background and the school logo, but the print I did doesn't look right to me.
1710966621320.png
 
Solventinkjet

Solventinkjet

DIY Printer Fixing Guide
Stormy Conner said:
I feel like though that as a designer if I am starting with a digital photograph to turn it into a poster for the proud parents of baseball players that I wouldn't lower the quality of the photo. Why go from a 300 DPI digital photo to a 72 DPI poster. I printed a small section of it and am not impressed. Looks wrong. Hopefully the designer is able to send me a higher quality version. They did a good job on the look of it incorporating the baseball picture with a cool background and the school logo, but the print I did doesn't look right to me. View attachment 170274
Click to expand...
You're right for sure. They most certainly have the full resolution file that will print better but either they don't know how to save a print ready file at full resolution or their software only allows them to create PNGs. It's fairly common these days for people to be using a free online design tool that only saves 72(ppi) pngs but since this is a school, I'd assume they used Adobe or Corel. I'd ask them what software they used to design in and if they can send a PDF, with downsampling images turned off, instead. That way you should get the full resolution image with any vector graphics that may be in the file as well.

My guess is that the school asked the Web design class to design the posters and they're just used to saving as PNGs. If that's the case, tell them to save as a PDF or a TIFF at 100-300 ppi.
 
Dasdesignguy

Dasdesignguy

Production Manager/Field Service Tech
PNG files are usually off of cameras. It's a humongous file but a 72 dpi. It's meant to be scaled down, so a 50% reduction would raise the dpi to 150.
 
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MonsterBabyBLN

New Member
OK. You are missing the basic understanding of dpi or ppi. And all answers do not help you. Because we don't know how large you want to print the sign?
You post the size is 100inches wide WHEN given 72 dpi.
That means if you print it at that exact size THEN you will have 72 point available to be spread along an inch.
But will you even print that big?
If you print the same file at 50inches width you will have 150 point per inch available to be printed.
Now all the other comments come in right.. No matter what it will all. Look good. It won't be enough for a fine art print but for a sign.

But that is the basic understanding of point or dots per inch.
 
C

ColorCrest

All around shop helper.
MonsterBabyBLN said:
But that is the basic understanding of point or dots per inch.
Click to expand...
Yet again, more conflation of terms continues the confusion.

A "point," as we are concerned here with graphic arts, measures 1/72 of an inch. A "point" is a separate specification from a pixel or a dot. A "point" is a fixed size where pixel and dot sizes are variable in size.
 
Gino

Gino

Premium Subscriber
You do realize that posters, signs and most other things we are producing are meant to be viewed from a normal distance. When I first started painting signs, we were told, flowers are meant to be smelled, not signs. If the viewer is that close to a sign or picture, that they can only see the eyeball like in the example shown, they are entirely TOO close to the subject matter. Step back and see what it is like at a normal viewing distance. Otherwise, they should take a real photograph with a proper camera and have it developed at the size they want.
 
Stacey K

Stacey K

I like making signs
If you want to send me a file, I'll take a look. I print 100's of these school banners a year. There are times that a couple photos are lower resolution than the rest. If it's just a couple I send them through my Topaz program to clean them up.
 
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MonsterBabyBLN

New Member
ColorCrest said:
Yet again, more conflation of terms continues the confusion.

A "point," as we are concerned here with graphic arts, measures 1/72 of an inch. A "point" is a separate specification from a pixel or a dot. A "point" is a fixed size where pixel and dot sizes are variable in size.
Click to expand...
That has nothing to do with the question.
The quote from the thread starter is simple math deviding the absolute pixels in the image by an inch.
I explained it simply and easy to understand.
 
bob

bob

It's better to have two hands than one glove.
Ideally you want to print at somewhere around 4 times the ppi of the input. This yields 16 printer dots per image pixel. On a CMYK printer this means 4^16 possible colors for each image pixel. If you're printing at 720 dpi then anything more than a 180ppi input is overkill and won't improve much of anything. I routinely print 150ppi images at 720dpi and the results are pretty much WYSIWYG. Fine by me.

Rule of thumb, the typical minimum viewing distance for any image is the image's diagonal.

The human eye is hard pressed to discern 1 part in 100 and cannot discern 1 part in 120. The farther away from the image the less difference the eye can see.
 
C

ColorCrest

All around shop helper.
Stormy Conner said:
UPDATE: Thank you everyone for all your help. I ended up using Photoshop to lower the size and up the resolution and everything is looking good. I guess I really didn't understand images like I thought. I have been too spoiled by vector art lately. LOL
Click to expand...
What size is the graphic supposed to be?
 
C

ColorCrest

All around shop helper.
Stormy Conner said:
its going to be printed at 24" xx 36"
Click to expand...
Thanks for the prompt reply.

Instead of using the inapplicable guide of "300 DPI to print good," what's better is to use a formula which accounts for the viewing distance of the print size. Such calculators may be found on line. The results should offer a good guide for the resolution of pixels per inch. You have the luxury in the ability to print tests to judge for yourself.

Also realize that your printer's actual resolution is likely set to image at a significantly higher DPI than 300, thus making 300 suspect. Further consider how it could be so that using 150 DPI could be satisfactory but only 1/2 of the 300 DPI prescribed. One or the other is likely a waste of time and materials.

Be reminded that pixels per inch and dots per inch are not necessarily the same.
 
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