I cannot get good screen capture without volume control images on my Android Phone. Therefore, I decide to use DDMS (Dalvik Debug Monitor) to help.
Launch DDMS in Linux
Download the latest Android SDK from here. Extract it to a folder. Then run [Extract Folder]/sdk/tools/ddms in terminal.
You won’t be able to see your Android device unless you enable USB debugging.
Enable Developer Options on Android 4.2+
At first, I cannot see Developer Options in Settings. According to Setting Up ADB/USB Drivers for Android Devices in Linux (Ubuntu) by Esau Silva, you have to open Settings→About phone then click on Build number 7 times to make it visible.
In Developer options, enable Stay awake and USB debugging. Now, you should be able to see your Android device in DDMS.
If you didn’t enable Stay awake, you might capture black screen when it goes to sleep mode.
Screen Capture your Device
In DDMS, first select your device, then choose Screen capture… from Device menu. Now you shall see what you could see on your Android device. Use Refresh to update and Save to save current screen capture.

Reference
- Android: Get the Android SDK
- Esau Silva: Setting Up ADB/USB Drivers for Android Devices in Linux (Ubuntu)