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High resolution screen captures System
Sometimes I want to get a higher resolution screen capture so I can include it in a printed document. Although my monitors are big, if I stretch a window out very large, that doesn't make the text, buttons, or menus bigger. This hint tells you how to scale the window itself, so you get a better screen capture.

Here's the problem: I want a screen capture with as many real, useful pixels in it as possible. If I have a window, say the Eclipse IDE, that looks good when it's, for example, 1000x800 pixels in size, it tends to just fill up with white space if I stretch it out to 1600x1050 (the size of my monitor). Certainly the icons and such don't scale.

If I take a screen capture of the 1000x800 pixel window, and then I scale it using a raster graphics program, the text gets scaled and jaggy, along with the UI elements. For many programs I find it time consuming and annoying to try to change all the fonts and preferences to make the text larger, and even if I do, the UI elements will be out-of-proportion to the text.

Instead I make use of this hint for a different purpose. You'll need to have Xcode installed to do this.

I open Quartz Debug (from /Developer/Applications/Graphics Tools/) and choose 'UI Resolution' from the Window menu. Then I slide the slider up to 1.25 or maybe 1.5 and stop. Now when I launch the program I want to capture, it is much bigger. Of course, the icons may look a bit blocky and some of the UI elements don't look right around the edges, but I've scaled everything uniformly. The fonts will scale smoothly and most of the UI elements scale smoothly. It has a much better look than going in and changing the text size to 18pt or 24pt, while leaving all the UI elements alone.

So now, when I make the window 1600x1050, I get more information in my screen capture. It looks better when printed. Fonts are scaled up smoothly and everything is in the same ratio as it normally would be.

[crarko adds: I tested this, and it works as described.]
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High resolution screen captures
Authored by: mattswain123 on Apr 21, '11 11:44:55AM

Everything seems to scale up fine apart from the menubar background. Any idea on how to fix that?



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If you'd rather not install Xcode...
Authored by: dilvish1984 on Apr 21, '11 12:02:34PM

In case anyone missed it, the other hint cited above mentions that you can access the same functionality without a full Xcode installation by using the "defaults" command:

defaults write -g AppleDisplayScaleFactor -float 1.25

By the way, you can also adjust this hidden parameter (and many, many others) by downloading and installing BlackTree's Secrets (system preferences pane) (no affiliation, I just think it's a great tool...) and using it to adjust the hidden System preference "Global User Interface Scale Multiplier" (in the "Appearance" section). (Be sure to read the associated warnings as any value other than 1 for this setting is not really very well tolerated by the system and/or various applications.)

Edited on Apr 21, '11 12:09:02PM by dilvish1984


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Re: If you'd rather not install Xcode...
Authored by: Uncle Asad on Apr 21, '11 02:31:29PM

…And if you replace -g with the app's bundle identifier, e.g., com.apple.preview, then you only affect the given app:

defaults write com.apple.preview AppleDisplayScaleFactor -float 1.25

defaults delete com.apple.preview AppleDisplayScaleFactor (again, replace com.apple.preview with -g if you used -g when setting the scale factor) will of course reset the scale factor to normal.



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Some caveats to high resolution screen captures
Authored by: newbill123 on Apr 21, '11 04:42:37PM

This works better in 10.5 Leopard than 10.6 Snow Leopard. As John Siracusa points out on Page 21 of his Snow Leopard review, Apple dropped the ball (and actually regressed) on updating some standard controls for resolution independence.

http://arstechnica.com/apple/reviews/2009/08/mac-os-x-10-6.ars/21

One other point, if this is for use in print, get a huge monitor and make the scaling factor an integral multiple (such as 2.0 times normal). Most speculation is that Apple never followed through on resolution independence because bitmaps at x1.5 and x1.25 will develop jaggies without including a huge number of special resolution cases.

But If this is for print, it may be worth your time to use exact multiples of the native interface. Yes, that requires a huge display. For example a 27" 2560x1440 iMac screenshot will only give you the information that could be displayed on a 1280 x 720 display (albeit at twice the resolution).



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High resolution screen captures
Authored by: Rainer101 on Apr 22, '11 11:13:00AM

There is an easier way to get a better print resolution.
Open the screenshot or image in Preview.
In Tools / Adjust Size …
Enter a higher resolution, for example 300 instead of 72 in the resolution field.
Now you can save the screenshot or any other image with a better image quality/resolution.



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Changing the dpi value stored in an image DOES NOT improve it's quality...
Authored by: dilvish1984 on Apr 22, '11 03:20:53PM

The procedure you describe has absolutely no effect on the data representing the pixels in the image (so would give no improvement to the printed output). The number you're modifying simply tells the software displaying the image how big a pixel is intended to be (1/72 of an inch or 1/300th of an inch in your example). Most software actually ignores this value, anyway, especially on raster-based images (as opposed to vector based, such as SVG files). Any software that actually does try to honor the new resolution you've given the image will simply display (or print) it at a much smaller apparent size (e.g. a 4 inch by 5 inch image originating at 72dpi would be displayed as 0.96 inches by 1.2 inches after having its resolution changed to 300dpi, regardless of the output device, screen or printer, in software that uses this value correctly).

So, all you've done by changing this value is to point out a flaw in any software that ignores it (which is most software, in my experience) and shrunk the output size of the image for any software that doesn't. You haven't actually improved the quality at all.

Now, if you were to actually scale the image data by, for example, changing the width and height values in that same Preview dialog (while the "Resample image" checkbox is on), you WILL actually "improve" it's quality (in other words add data), but this data is interpolated by the software and can often times create artifacts (jaggies), though the algorithms have greatly improved since the early days. What the OP is trying to accomplish is to create an image that actually contains more accurate data in the first place rather than relying on later upscaling.



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High resolution screen captures
Authored by: gmachen on Apr 22, '11 12:32:16PM

If one Screen Zooms before doing the capture, the saved screen grab is the larger size.
(The [command key of your choice]-two-finger-swipe-upward to Screen Zoom is controlled in the Trackpad System Preference.)



[ Reply to This | # ]
This wouldn't accomplish the same goal, though...
Authored by: dilvish1984 on Apr 22, '11 03:27:29PM

The OP is trying to get more original, precise pixel data in his screen captures so that printing comes out better. The method you're describing just upscales the image before capture, rather than after capture. The algorithm Apple uses in screen zooming is pretty darn good, but it does still introduce artifacts that the OP's method may very well avoid (especially in text and other vector based elements of the screen display).



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