After standard installation, PrtScr is set to load itself at Windows startup, and replaces your normal screen printing. Of course, you still have the option to load it manually, and assign your own hotkey.

To make a normal capture, press Prt Scr, optionally draw some annotation (using the right mouse button), then select the part to grab using the left mouse button. Hold CTRL while clicking to make rectangle annotations or selections.
The little reminder window displayed on the right fortunately fades out when you approach it, so that you can capture what's behind.

In order to capture the topmost window, use the standard ALT+Prt Scr (a lot of people aren't aware of this hotkey, but yes it's a standard) or, if you defined another hotkey, press ALT+your hotkey.

Tip: for a quick, full-screen capture, press Prt Scr twice, or press Prt Scr, then press Space, or Return, or simply press the left mouse button once (if the selection is too small, PrtScr will capture the whole screen).

Once your capture is done, you have several options. A single click will send your capture to your desktop. Other commands let you save your capture in other formats, email it as an attachment, edit & print it (the behavior depending on what your system has linked to the JPG, PNG & BMP image formats).
JPG & BMP formats are opaque, that is, even if you made a freehand selection, the bitmap will be rectangle (it will include the part around the selection nicely blurred). The PNG format allows saving the selection along with its alpha channel. As a reminder, JPG is a lossy format, while BMP & PNG are lossless formats. To send through the internet, JPG or PNG are the best options.

The fancy, giggling capture preview can also be clicked & dragged to other tools. Note that the shadow around the capture preview is eye candy that won't appear in your final result.

PrtScr will (optionally) pre-fill the title entry with the title of the topmost window, and the comment entry with its URL if that window is a browser (so that you know where that screenshot came from). The title entry is used to compute capture filenames when necessary, while the content of the comment entry will be written at the bottom-left of the final capture. Both title & comment entries are optional, though.

Capture files are stored (when necessary) in your local documents folder, in the 'My Screen Captures' folder.


PrtScr also acts as a magnifier. Within a capture, press one of the (many) zoom keys to zoom in/out. You may also enter the zoom mode directly by using Ctrl+Prt Scr (or Ctrl+your own shortcut key). Click & drag to pan the view around.

This mode allows you to read pixel coordinates, measure rectangles, read pixel colors, or average pixel colors (if a selection is made). This magnifier mode is very useful for GUI or web designers to check accuracy.

Note: the captured color is always copied (has hexadecimal RGB) to the text clipboard. So you may simply escape the magnifier mode (Escape) and paste the color value. Also, it's formatted as BBGGRR, you might have to flip BB & RR depending on what you're doing.

Keyboard shortcuts

LMB (Left Mouse Button): selects the zone to capture and completes the capture (so this should be your last step)
RMB (Right Mouse Button): draws annotations over pre-capture
Ctrl+LMB/RMB: selects/draws rectangle
Mouse wheel: changes thickness of annotation ink
Delete/BackSpace: deletes most recent annotation ink
Escape: cancels capture
Return, Space: selects whole screen for capture
ALT+Prt Scr: captures topmost window only
(Ctrl+)mouse wheel, NumPad +/-, PgUp/PgDn, Home/End: zooms in/out capture
Arrow keys: enlarges/shrinks capture
NumPad 7/9/3/1: set capture corners
MMB (Middle Mouse Button): toggles resampling quality
RMB: gets back to capture