Resolution same as dpi?

[michael31986]

Whenever I save images online from this specific site they save as 72 resolution.

If I wanted to print them could I change it to 300?


I’m assuming however apple saves the images is however they were put online, cause other images online sometimes same as 100 resolution or 300.

 

[artfossil]

Yes, for printing resample them to 300 dpi.

 

[dukebound85]

no

Resolution is total # of pixels

DPI is is a function of pixel density

 

[michael31986]

Yes, for printing resample them to 300 dpi.

But why are some images saved from internet 72 resolution while others are 300?

Is it how the personal uploaded the photo….

I’m guessing 72 is good for web and phones etc. just not printing

 

[HobeSoundDarryl]

Higher resolution images than 72 are created that way or scanned or shot with a camera at high(er) resolution. For example, if you open a virtual page on which to create an image in Photoshop or Pixelmator or similar, you can select the dpi. If I select- say- 600dpi and then create some kind of image on that page, the image I create will be 600dpi when I export it for other uses (like printing it).

72dpi is generally considered the LOWEST resolution choice for anything online. Printing it will result in the "jaggies" (rough edges) because printers print at much higher resolution than screen (72dpi) resolution. Sizing them bigger only makes that worse. For example, if you grab something that is 400 pixels X 400 pixels at 72dpi and you want to size it up to 1000 pixels X 1000 pixels, it's going to look "jaggie" on screen and even worse than the first example when you print.

Opening a file at 72dpi and then exporting it at something higher (dpi) is basically "creating" pixels... with the computer trying to best guess what image detail should go in those new "pixels" you are creating. This can actually work OK for some purposes but it's nowhere near a good printing strategy in general.

If the best you can get is 72dpi, try to get the image at the highest resolution you can get (as LARGE as you can get it). A so-so option for that: print it without sizing it. Then take a high resolution picture or scan of the native size version you just printed to basically scan it into your system at a higher resolution than 72dpi. This is NOT as good as getting an image already at a higher dpi either but it will probably look- and certainly print- better than the first option.

BEST POSSIBLE OPTION (for printing intentions): source the image at highest DPI, ideally at least 300dpi at the largest width & height you'll want to print it. For example, if you want to print something at 6 inches X 6 inches, source your image at at least those measurements and at least 300dpi. In a pinch, you can back down from 300dpi but you should strive for at least 300dpi if the ultimate intent is printing.

If you only want to display something on screens, you can readily get by on sourcing images at 72dpi and they will generally look good if you don't try to size them up much bigger than their native size. A good general rule when sourcing 72dpi is always go with the LARGEST size you can get. Why? Because sizing any image DOWN to a smaller size will maintain a sharp look on screens. It's trying to size UP from a (too) small image size that you start introducing what will look like blur at first and print as jaggies.

 

[dwig]

But why are some images saved from internet 72 resolution while others are 300?

Is it how the personal uploaded the photo….

I’m guessing 72 is good for web and phones etc. just not printing

Yes, the PPI value is set by the app that created the image. If the value is left blank in the image's metadata it is common for apps to to assign 72ppi, though some assign 300ppi. Not all bitmap formats support these virtual items and in those that do they are optional.

Resolution of a bitmap file is always just the size in pixels. Size in inches (or cm, ...) and PPI (Pixels Per Inch) are virtual concepts. You can think of them as notes to other programs saying "hey, if you have the concept of a page or virtual page, place this image so that there are x pixels for each inch". Often PPI is incorrectly labeled DPI (Dots Per Inch). DPI is only correctly use when discussing a marking engine (printer's ink heads, laser printers dot spacing, ...) and is NEVER correctly used in reference to a bitmap file.

Check out this YT vid on the topic:

 

[michael31986]

Higher resolution images than 72 are created that way or scanned or shot with a camera at high(er) resolution. For example, if you open a virtual page on which to create an image in Photoshop or Pixelmator or similar, you can select the dpi. If I select- say- 600dpi and then create some kind of image on that page, the image I create will be 600dpi when I export it for other uses (like printing it).

72dpi is generally considered the LOWEST resolution choice for anything online. Printing it will result in the "jaggies" (rough edges) because printers print at much higher resolution than screen (72dpi) resolution. Sizing them bigger only makes that worse. For example, if you grab something that is 400 pixels X 400 pixels at 72dpi and you want to size it up to 1000 pixels X 1000 pixels, it's going to look "jaggie" on screen and even worse than the first example when you print.

Opening a file at 72dpi and then exporting it at something higher (dpi) is basically "creating" pixels... with the computer trying to best guess what image detail should go in those new "pixels" you are creating. This can actually work OK for some purposes but it's nowhere near a good printing strategy in general.

If the best you can get is 72dpi, try to get the image at the highest resolution you can get (as LARGE as you can get it). A so-so option for that: print it without sizing it. Then take a high resolution picture or scan of the native size version you just printed to basically scan it into your system at a higher resolution than 72dpi. This is NOT as good as getting an image already at a higher dpi either but it will probably look- and certainly print- better than the first option.

BEST POSSIBLE OPTION (for printing intentions): source the image at highest DPI, ideally at least 300dpi at the largest width & height you'll want to print it. For example, if you want to print something at 6 inches X 6 inches, source your image at at least those measurements and at least 300dpi. In a pinch, you can back down from 300dpi but you should strive for at least 300dpi if the ultimate intent is printing.

If you only want to display something on screens, you can readily get by on sourcing images at 72dpi and they will generally look good if you don't try to size them up much bigger than their native size. A good general rule when sourcing 72dpi is always go with the LARGEST size you can get. Why? Because sizing any image DOWN to a smaller size will maintain a sharp look on screens. It's trying to size UP from a (too) small image size that you start introducing what will look like blur at first and print as jaggies.

Thanks for the info. I mainly get my album art from iTunes album art site and those images are 72 resolution. They display great on iPhone and I don’t think that increasing resolution would help with how it looks on iPhone.

But I’m assuming based on what you said if I wanted to print I would change the resolution to 300 so it prints better..


Hopefully it wouldn’t make it to blurry by increasing to 300 resolution

 

[HobeSoundDarryl]

That's the bigger point. Changing the resolution to 300dpi from 72dpi is asking the computer to create pixels. What works is going from 300dpi to 72dpi- no resolution lost. The other way cannot create the detail that would be there if it was originally created at 300dpi.

So if you want to print something, you should try to get it at HIGH dpi. 300dpi is a good target.

If you want an image only for screens, 72dpi is generally fine. Printing 72dpi will look blurry. Sized up a bit will look jagged-y. Creating pixels by changing dpi doesn't make 72dpi into 300dpi.

 

[dwig]

That's the bigger point. Changing the resolution to 300dpi from 72dpi is asking the computer to create pixels. ,,,

Maybe, and maybe not ...

... The PPI (NOT dpi !!) is not an "real" property of a digital image. It is just a bit of data that cues a displaying or printing program how to display the image relative to other items. It will have absolutely no effect on screen display in things like image viewers and browsers. Changing the PPI simply changes the related "size in inches/cm/..." and nothing else unless the tool/app you use to make the change is programmed to maintain the "size in inches/cm/..." and resamples the image, changing the real size in pixels either up or down. Apps like Ps have an check box in their resize panel that lets you decide whether to resample or not.

 

[HobeSoundDarryl]

Yes, I didn't want to get too technical with OP. He's perceiving converting a 72dpi image to 300dpi makes it printable and presumably sharp (when printed). We could dig deep into the specifics of printing vs. screen and cover all kinds of "heady" things but OP seems to have at least a basic concept of DPI, so I stuck with talking his language.

I perceive he's trying to print something from images being sourced on the internet. The basic concept of grabbing 72dpi images and converting them to 300dpi is easy to grasp even if not technically completely relevant. However, if he has a basic understanding of dpi as it appears (except for the converting part), sourcing images tagged at higher dpi is going to get him a more printable image... without really needing to develop much of an understanding of "the rest."

 

[FSmertz]

First, DPI stands for "dots per inch" and is a printer output metric based on the number of dots spritzed on the paper. My Epson printer can print at 1440 DPI or 2880 DPI. It's a common misnomer to use DPI when you intend to refer to PPI, "pixels per inch." Even Adobe with Photoshop still gets this wrong after so many years. PPI is an input metric and refers to pixel density and is only relevant to printing. (I'm ignoring monitor-based PPI as that's a hardware-based metric that is irrelevant to the OP's stated concern). It is not a measure of image size which itself is only measured by pixel length and width.
Images on the web do not have a PPI (or a DPI) because there are zero inches on the web, only pixels. The listed 72 figure is an artifact of the software's image metadata and is meaningless. What matters are the pixel dimensions in the context of printing. You then see how those dimensions spread over the square inches of the artwork you are printing. If you don't know what output size in inches your print is, then you cannot ascertain the PPI.

Magically increasing the PPI number in software will require that the inch-based dimensions of the image be scaled accordingly smaller. Software can be configured to resample the image (create pixels to make it larger) to satisfy the desired PPI number. But that risks quality.
For example, an image in Photoshop is shot at the aspect ratio of 2:3 and has dimensions of 4727x3151. At 8x12-in, it shows the PPI as 394. To maintain the same 2:3 aspect ratio, I can alternately print it out at 12x18-in with a PPI of 263. The pixel dimensions of 4727x3151 have not changed; what has changed is the density of the existing pixels in relationship to the overall image size.
There is nothing magical about 300 PPI. The quality of print being viewed depends on the viewing distance and the eyesight of the viewer. The native input resolution of Canon and HP printers are 300/600 (for finer quality) PPI; for Epson it's 360/720 PPI. Some people can see slight quality differences in prints output at the higher densities and it depends on the content as well. Lots of larger prints output fine at 220 PPI.
Hope this helps.

 

[Ruggy]

Thanks for the info. I mainly get my album art from iTunes album art site and those images are 72 resolution. They display great on iPhone and I don’t think that increasing resolution would help with how it looks on iPhone.

But I’m assuming based on what you said if I wanted to print I would change the resolution to 300 so it prints better..


Hopefully it wouldn’t make it to blurry by increasing to 300 resolution

Yes, as I think others have said: 300 is generally right for printing.
If the image is very small then you will need to resample it so it's big enough otherwise as you say, it'll be blurry.
It's quite a simple bit of maths. If you want it 6 x4 then you need (6x300=1800)x(4x300=1200) so you would set the resolution to 300 then set the pixel size to 1800 and tick the box to resample. That way it uses an algorithm to add more data. Of course it might not be exactly the right shape so you will then have to crop to the right shape........
The trouble with printing is it gets more complicated the more you get into it.
Before you know it I'm afraid you'll be talking about colour spaces and profiling.

 

[ignatius345]

I say this as a graphic designer with years of experience in print and screen: unless you're sizing images for print, dpi or ppi is a confusing measurement you probably don't need to pay any attention to. Watch the actual pixel dimensions instead. An image of, say, 1000px square for album art is probably going to look sharp and detailed on your Mac or your phone. Give your application a big enough image and let the screen scaling handle the behind the scenes stuff.

 

[michael31986]

Yes, I didn't want to get too technical with OP. He's perceiving converting a 72dpi image to 300dpi makes it printable and presumably sharp (when printed). We could dig deep into the specifics of printing vs. screen and cover all kinds of "heady" things but OP seems to have at least a basic concept of DPI, so I stuck with talking his language.

I perceive he's trying to print something from images being sourced on the internet. The basic concept of grabbing 72dpi images and converting them to 300dpi is easy to grasp even if not technically completely relevant. However, if he has a basic understanding of dpi as it appears (except for the converting part), sourcing images tagged at higher dpi is going to get him a more printable image... without really needing to develop much of an understanding of "the rest."

Thanks for the info. I think I confuse dpi with resolution. On the mac when you go to resize it shows 72 where it says resolution.

I was under impression that’s same as dpi.

I can’t change how the image was sourced online. It’s by default saving at 72 resolution.

 

[HobeSoundDarryl]

72 is almost certainly dpi. That’s a standard for web images but not good for printing. You’ll see the issue when you try to print it… especially if you want to make it bigger.

At this point, I suggest just printing it and see what you think. If you don’t like the sharpness on paper, refer back to post #5 for my best suggestions.

 

[FSmertz]

72 is almost certainly dpi. That’s a standard for web images but not good for printing. You’ll see the issue when you try to print it… especially if you want to make it bigger.

At this point, I suggest just printing it and see what you think. If you don’t like the sharpness on paper, refer back to post #5 for my best suggestions.

There is no "DPI" nor "PPI" for online images because there are no inches on the web. Only pixels matter. 72 is a meaningless artifact from the software that originally exported these images. Historically, the 72 number is related to the original Mac 128 and how "WYSIWYG" was rendered on the Imagwriter printer. Been there, done that.

 

[michael31986]

72 is almost certainly dpi. That’s a standard for web images but not good for printing. You’ll see the issue when you try to print it… especially if you want to make it bigger.

At this point, I suggest just printing it and see what you think. If you don’t like the sharpness on paper, refer back to post #5 for my best suggestions.

Thanks. I’ll try to resample to 300 if I need to bring it and see how the quality is.

I guess I just wanted to make sure there was no other way to save the image. I thought maybe I could change settings on mac to save it at higher resolution but I’d it’s the native image than I can’t change how it was uploaded online.

 

[theluggage]

I was under impression that’s same as dpi.
I can’t change how the image was sourced online. It’s by default saving at 72 resolution.

That’s 72 pixels per inch (PPI) which - as some people have pointed out - is often wrongly described as DPI (even in some software that should know better) but that’s not really the issue here, so don’t get bogged down in DPI vs. PPI…. and “resolution” can mean different things - including PPI - depending in the context.

The point is, a photo doesn’t really have a valid PPI. Just a width and height in pixels.

Some image formats don’t include any physical size or PPI data. Otherwise, if the image came from a flatbed scanner, or was generated by graphics/word processing software that works in real-world units, then it has a known “real world” size so the PPI will actually mean something, and some software will use that to decide how large to display the image, but otherwise it will just get set to a default value which is often 72ppi (because that makes 1 pixel = 1/72” = 1 point, and that was also the standard resolution of Mac displays back when desktop publishing was taking off)

Paste a 1000x1000 pixel image into an editor of some sort and set the physical size to 5”x5” then it becomes a 200 PPI image. Print it out and it should come out at 5”x5” - and let the printer driver worry about converting resolution (and DPI vs PPI - which is a can of worms).

 

[HobeSoundDarryl]

Thanks. I’ll try to resample to 300 if I need to bring it and see how the quality is.

I guess I just wanted to make sure there was no other way to save the image. I thought maybe I could change settings on mac to save it at higher resolution but I’d it’s the native image than I can’t change how it was uploaded online.

No way to actually upgrade the image. For example, switching 72 to 300 or 3000 or 30000 is simply asking the computer to create detail that is not there.It will best guess and that can sometimes yield a bit better looking print in some cases, mostly because the guesses can soften rough edges at print resolutions. What else does softening edges do? Make it seem a little blurry when printed.

But generally, 72 will disappoint when printing.

This thread is filling with other considerations- including technically correct information that goes beyond a basic concept of dpi- but very simply: if you want to print an image you have and it is 72, it will likely print poorly. If you have to size it up from whatever size it is, making it larger will print it worse. If you have any way to source the same image at much bigger width & height or if you are downloading it from one of the stock imagery sites, you can choose both height & width AND dpi or ppi. Generally for printing, the latter at 300 will print well. Even down to 200 can still print good… much better than 72.

For height & width, get at least the size you need… and perhaps larger than you need if 72 is the only option.

There’s lots of good/correct info also in this thread but it seems we are playing a game of who knows the most about printing concepts instead of focusing in on a relatively simple need. Trying to cover all relevant details could be a thick BOOK of information. For your simple task, generally bigger Height/width/dpi-ppi ORIGINAL will print better.

Tip: if you have just grabbed something from an image search or website, try Google reverse image search- which searches by image instead of by text (meaning you upload the image you have for the search) and the very same image might be found elsewhere at a higher width & height and/or dpi/ppi. If someone originally took a picture of whatever it is, there probably IS a better (for printing) version of it somewhere else online. If it is created art, not many artists will create on a small canvas at only 72dpi. So again, an original might be found that is MUCH better for printing. Worth a simple & free try!

 

[michael31986]

These are the images I save from the net

http://is5.mzstatic.com/image/thumb/Music112/v4/51/6f/aa/516faa6e-7c39-bd5f-f74c-52923d1d87f0/source/100000x100000-999.jpg

 

[FSmertz]

These are the images I save from the net

http://is5.mzstatic.com/image/thumb/Music112/v4/51/6f/aa/516faa6e-7c39-bd5f-f74c-52923d1d87f0/source/100000x100000-999.jpg

The pixel dimension is 3000x3000. Without sampling, you can create a 10x10-in print at 300 PPI. At 200 PPI, a 15x15-in print can be created. The 72 number that shows up by default is no more meaningful than the above numbers, it merely can output a print at 41.667x41.667-in. In my experience of producing fine prints for over twenty years, I'd say you can get a decent looking print without many telltale artifacts at about 220 PPI.

 

[michael31986]

The pixel dimension is 3000x3000. Without sampling, you can create a 10x10-in print at 300 PPI. At 200 PPI, a 15x15-in print can be created. The 72 number that shows up by default is no more meaningful than the above numbers, it merely can output a print at 41.667x41.667-in. In my experience of producing fine prints for over twenty years, I'd say you can get a decent looking print without many telltale artifacts at about 220 PPI.

Lol I thought the 72 was the damn dpi. Ugh.

I been resizing to 1000 by 1000 for alvum set purposes.

 

[dwig]

... In my experience of producing fine prints for over twenty years, I'd say you can get a decent looking print without many telltale artifacts at about 220 PPI.

Quite true.

It depends on print material, printing method, and end use viewing distance, but certainly 220ppi is fine for most situations. In fact, 300ppi is too high for some use (offset printed magazines and brochures). Offset printed materials that use a 133 line halftone screen reproduce best with images at 266ppi or lower. The rule to follow there is 1.5-2.0x the line screen frequency. Higher or lower will result in less sharp reproduction.

I regularly deal with needing to upsample images to get 200-300ppi at the final printed size. At the gallery where I work we standardize on 300ppi files, but this is for the uniformity that is needed from some of the automated scripts we use. Slightly lower PPI is actually fine for our printing on water color paper, canvas, and aluminum (dye sublimation transfer).

 

[michael31986]

The pixel dimension is 3000x3000. Without sampling, you can create a 10x10-in print at 300 PPI. At 200 PPI, a 15x15-in print can be created. The 72 number that shows up by default is no more meaningful than the above numbers, it merely can output a print at 41.667x41.667-in. In my experience of producing fine prints for over twenty years, I'd say you can get a decent looking print without many telltale artifacts at about 220 PPI.

So what is the ppi of the image in the link when it’s saved. If it’s not 72. What does max default save it as?

 

[FSmertz]

So what is the ppi of the image in the link when it’s saved. If it’s not 72. What does max defaultsave it as?

72 is meaningless. It's an artifact of the software used to process the image because they had to fill in the PPI field with something. Image files don't have a firm or saved PPI. It's a measure of density based on desired print size in inches (that's the "I" in PPI), as I've attempted to illustrate. If you make a print at 10x10-in, then the image PPI for this file is 300. If you make a print at 15x15-in, the PPI for this file is 200. It's all the same file, nothing different is "saved" with each different PPI. Now you can resample the image file to create more pixels which could give you larger prints--but this is an entirely different file. But even with this file you can still have relative PPI numbers, so instead of 300 PPI enabling a 10x10-in print, with more pixels added, 300 PPI could get you a 12x12 or 14x14-in print--it just depends how much you dope up the image file. Topaz Gigapixel AI does a really good job at upsizing and I've used it up to 6X--which is amazing.