Screen capture tutorial

Draft

This is a short screen capture tutorial.

Grabing static pictures of applications

Grabbing static screenshots involves usually 2-3 steps:

• Either grab the whole desktop, a window or some random rectancle
• Crop the image if needed (i.e. select/save a part)
• Reduce the image size and save in other formats if needed.

Capturing with the screen capture tool

There are several kinds of tools:

• Small and usually free screen capturing utilities, e.g. MwSnap and ScreenHunter for Windows.
• Capturing tools embedded in image manipulation (or other) programs, e.g. The GIMP

To capture a screen there are usually three methods

• Capture the whole screen
• Capture a single application window
• Capture a rectangular area (you must click on a corner and then drag the mouse)
• Capture a fixed rectangular area (you define its size beforehand)

Capturing with the print Screen Method

"Print Screen" means to make a copy of the whole screen:

On Windows XP

Hit the Print Screen key (sometimes labeled "Prnt Scrn") which you usually can find somewhere in the top right of your keyboard. On some other keyboards (I have swiss-french ones), you may have to hit shift-prnt scrn".

This operation will put the screen capture into the clip board. Therefore after pressin the key you won't see anything, so simply paste it into an imaging program with either one of the two methods:

• Acquire from Paste
  • In Gimp: "File->Acquire->Paste as New
• Paste into an open document, e.g. ctrl-v (but you may loose information depending on what editing software you are working with)

The print screen method seems to produce best results, since it seems to have less problems capturing some tricky multi-paned windows like the Adobe CS3 desktops for which all my screen capture tools didn't word (some tabs did not show).

On Ubuntu (Linux)

• Hit the Print Screen key to capture the whole screen (also works on double monitor twin-view setup).
• Alternatively, hit ALT-Print Screen to capture the window over which your mouse pointer sits.

This tool will produce *.png image and a preview/popup menu will allow to save it somewhere. Btw this applications is also available under Applications->Accessories->Take Screenshot.

Here is copy of my desktop while writing this article:

Daniel K. Schneider's Linux Desktop

• From left to right: GIMP, Firefox, the capture popup, a terminal, Xemacs (Wiki mode) and Firefox again ....
• I use Ubuntu as my desktop OS and as you can see I got some nice screen real-estate (3500px wide, which is essential for writing wiki articles at my age).

Reducing image size

(Disclaimer: I am not much of an image expert).

Frequently, screen capuring programs save per default in the lossless png format. PNG is efficient for graphics, but heavy if you have included bitmaps. You may set png to a maximal compression rate (9), but the difference gained may not be very important.

Therefore, if you save screendumps that contain bitmaps, you should save in *.jpg. A lossful compression quality of 70 should be ok. Here is an example of my Desktop that should be self-explaining:

The original 3500x1200 pixels screen capture:

1621618 2007-07-30 14:34 desktop-dks.png
 596814 2007-07-30 15:14 desktop-dks.jpg
1600991 2007-07-30 15:17 desktop-dks-max-compression.png

Reduced versions:

 181255 2007-07-30 15:02 desktop-dks-1760x600.jpg
 625596 2007-07-30 15:05 desktop-dks-1760x600.png
 304380 2007-07-30 14:36 desktop-dks-1000x341.png

Grabing movies of user interactions

(to be written).

Software

Free screen capture programs

Windows

• MwSnap (the one I use
  • It has 5 capuring modes and is fast (minimizes to the tray)
  • Supports several file formats for saving
• Screen Hunter (free basic version, not tested).

MacOS X

• SnapNDrag
  • Basic version is free and supports several formats. The Pro Version can crop.

Free image manipulation programs

In principle, they include some capturing tool

Multi-platform

• The GIMP (The GNU Imaging Program)
  • Free and sophisticated.

Windows

• IrfanView
• For those who have office installed (so I don't think it's free) there is the Microsoft Picture Manager (good enough for a little bit of cropping etc.)