Something wrong with screencapping function

[UltimateKuriboh]

Just got a new Macbook Pro with Retina display, mid-2014 model. I had all the stuff imported from my previous MacBook Pro (2011 model) with Yosemite transferred onto this new computer.

With my old computer, I could do Command +Shift + 4 to screencap any area I wanted, no problem. But now, the screencaps I take are bigger than I expected. For example, I noted that when I took an example screenshot, I took it at 255 (width) by 100 (height) px. When I open it up on Preview, it looks the same size as when I took the screenshot. But when I examine the dimensions in Tools --> Adjust Size... , it turns out to be 510 by 200 px, doubled in size. I first noticed this after I uploaded a screencapped image to a website, where the image was twice as big before.
Said example: http://i.imgur.com/NQHe6H7.png

Is there a way to change this? My internet browser (Google Chrome) was at a standard 100% in terms of zooming in/out when I took the screenshot, and I can't think of how else to research this problem. Downloading images from online has no effect on their size (after I confirm dimensions in Preview and uploading to a site), so I assume it's the screencapping function.

 

[dyt1983]

edit: To remove personally identifying information not relevant to the thread.

 

[UltimateKuriboh]

It's a byproduct of using a retina display. Even if you select an application's Get Info->Open in low resolution and capture the window rather than an area, it will still screen cap at the resolution that everything is rendered. If you use an external non-retina display, the images will be the size selected in screen capture. Similarly if you change the screen resolution to be native, screen caps will match but in normal use everything will be tiny.

I only just found this out through http://www.macissues.com/2014/03/29/adjust-retina-macbook-screenshots-to-be-actual-size/

But luckily, I found a link in the comments showing me a workaround: http://blog.lanceli.com/2012/08/downscale-screenshot-at-hight-resolution-on-retina-mackbook-pro.html

EDIT: I'm still facing some trouble with this method though. Hold on...

 

[UltimateKuriboh]

After following the directions (I did Step 1 and Step 2, without installing that GitHub thing), still doesn't seem to work.

It works perfectly fine when I test my "HalvingScreenshotSizetoNormal" in Automator, in that I get a double-sized screenshot and a normal screenshot saved to my Desktop. But whenever I use Command + Shift + 4, it only does the 1 double-sized screenshot. So I think I'm implementing the function incorrectly; could anyone help me out?

Additionally, I'd appreciate if someone could provided a modified version of that "service" to produce *only* the "normal" screenshot on my Desktop.

2 images of what I did in the Shortcuts pane of System Preferences --> Keyboard: http://imgur.com/gKu3uHM,yQjEnI7#0