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Images, Graphic Design, and Digital Photography Discussion of all things graphics.

How do I take screen shots at my displays native pixel density? ...NOT 72 PPI!


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davidlones365

 
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My Mac (I assume all Mac's, and most computers in general) always takes screen shots at 72 ppi... why is this? Also, it seems 72 ppi is the default pixel density for most image editing software. Again, WHY??? NO display today still uses 72 ppi and I'm pretty sure printers print at 300 ppi/dpi (whatever). Doesn't this seem counter-intuitive when it comes to the image size? I'm not much in to professional photography or graphics design, but from what little I've done this seems like a serious issue!

Regardless, I still need to take screen shots at my displays native pixel density... or I at least need to somehow change the default.
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schweb

 
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Because 99.9% of the time a screen shot is meant for sharing in email or online. 72DPI is fine for those purposes and provides a small file size. A 300 DPI file size is huge compared to 72 without any added benefit in those 99.9% of scenarios.

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davidlones365

 
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Quote:
Originally Posted by schweb View Post
Because 99.9% of the time a screen shot is meant for sharing in email or online. 72DPI is fine for those purposes and provides a small file size. A 300 DPI file size is huge compared to 72 without any added benefit in those 99.9% of scenarios.
...umm, an images pixel density has no effect on its file size. (???)
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davidlones365

 
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Let me rephrase my question:
If I'm not able to adjust the default pixel density of my screenshots, is there a third-party screen capture app available that would allow this?
...or do I have no resort to manually changing it after the fact using something like Pixelmator or Photoshop?
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chas_m

 
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Actually, pretty much all digital cameras (yes, even those 20MP cameras) shoot at 72dpi.

By default, screen shots taken on a Mac open in Preview. Guess what Preview can easily do.
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davidlones365

 
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Quote:
Originally Posted by chas_m View Post
Actually, pretty much all digital cameras (yes, even those 20MP cameras) shoot at 72dpi.

By default, screen shots taken on a Mac open in Preview. Guess what Preview can easily do.
Yeah, I know... 72 is apparently the default everywhere. There is absolutely NO logical reason for this!

...and simply "zooming it fit" in Preview never gets the end products actual size exactly right, (unless I do the math my self and come up with some random number like 87.0086522%). If the pixel density where accurately represented, simply choosing 100% or "actual size" would be all I'd need to do.
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Your iMac's display should be about 102ppi. The whopping 30ppi difference is hardly noticeable on the screen. This, to be honest, is why most images for web are 72ppi. So this is actually a very logical reason, and at one point in the not too distant past most monitors were are 72ppi anyway. IMHO it really doesn't matter until you PRINT anyway.

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you could try doing a screen recording, and then exporting 1 frame as a picture?

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davidlones365

 
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Quote:
Originally Posted by Dysfunction View Post
Your iMac's display should be about 102ppi. The whopping 30ppi difference is hardly noticeable on the screen. This, to be honest, is why most images for web are 72ppi. So this is actually a very logical reason, and at one point in the not too distant past most monitors were are 72ppi anyway. IMHO it really doesn't matter until you PRINT anyway.
Actually, mine is 99ppi (to be more precise, 99.28ppi) ...and there is a noticeable difference:
(screenshot uploaded here)
Both images have been scaled to actual size.

Yeah, most monitors were 72ppi... 20 or 30 years ago!!
If you can't see a difference in monitor resolution between then and now, I have nothing to say!

How can purposely using a lower quality than the actual display for a screenshot possibly be "logical"???
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davidlones365

 
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Quote:
Originally Posted by robduckyworth View Post
you could try doing a screen recording, and then exporting 1 frame as a picture?
How would one do that? Seems even more time consuming than using Pixelmator to edit a regular screenshot.
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Dysfunction

 
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Here's a legitimate solution then... write something better

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PPI for VIDEO (as in the monitor that you, and everybody else is viewing the web on, no matter what kind or size of monitor) is irrelevant, and the notion that PPI matters is absolutely false and a HUGE misconception. The ONLY thing that matters is resolution, but resolution of a picture and not the screen. This also goes for scanning.

Your monitor, my monitor and everybody's monitor ignores PPI/DPI values, because those things are only defined for PAPER. The real issue I believe, is how much the screen shot is compressed. You can change the dpi/ppi values all you want (if you could) but that wouldn't make a bit of difference on a monitor.

There are more than a few articles on the web which you can Google, that explains what I'm saying in much more detail. A quote from the article I'll post right below it:
Quote:
In our world of digital images, dpi is for printing images on paper, or for scanning images from paper or film. Dpi means "pixels per inch" and it implies inches on paper, or film, or someplace where inches exist. Paper is dimensioned in inches, but video screens are dimensioned in pixels, and there is no concept of dpi in the video system.
Read the article, it's pretty good and goes into detail. It was a random one I had come across when searching for what I wanted to explain:

Say No to 72 dpi

Fairly long article, and page 2 has really good info so try and read the whole thing.

Doug
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davidlones365

 
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Quote:
Originally Posted by Doug b View Post
PPI for VIDEO (as in the monitor that you, and everybody else is viewing the web on, no matter what kind or size of monitor) is irrelevant...
The article you provided at times seems to agree that what I'm trying to do is an appropriate use of ppi/dpi... presenting an image at "actual size" on the screen and in print. ("Approximate Actual Size On the Screen" section)
Yet, in its summery, it seems to dismiss that example???
I'm aware that the video system ignores ppi data, relying only on the given pixels, but its rather obvious that the software providing those pixels CAN and often DOES recognize pixel density and it would be stupid not to put that into consideration.


Quote:
In our world of digital images, dpi is for printing images on paper, or for scanning images from paper or film. Dpi means "pixels per inch" and it implies inches on paper, or film, or someplace where inches exist. Paper is dimensioned in inches, but video screens are dimensioned in pixels, and there is no concept of dpi in the video system.
...this quote does a good job of summarizing my example, but again, it confuses the basic points.


If I take a screenshot of my screen, I expect the saved image to include all correct data available about the shot, including screen size (as pixel density).
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Quote:
Originally Posted by davidlones365 View Post
Yeah, I know... 72 is apparently the default everywhere. There is absolutely NO logical reason for this!
Well, yes there is -- it's called the Lowest Common Denominator. Not that I'm defending it, I'm just saying there is some rationale behind it.

You may have missed the second part of my post, where I mentioned that Preview can resize the screenshot to be pretty much whatever dpi you want. It's in the Tools menu under "Adjust Size."
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schweb

 
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Quote:
Originally Posted by davidlones365 View Post
...umm, an images pixel density has no effect on its file size. (???)
Um, actually it does, unless you plan on shrinking the 300DPI version down to a tiny postage stamp size compared to the original 72DPI version?

Is that what you want to do?

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