A few select HTC and Samsung Android phones have just received an app that lets you flash kernel and recovery images straight from within the Android OS (while booted). The app, called Flash Image GUI, comes to us from XDA-Developers forum member joeykrim, and is basically a GUI interface for the Linux binary. The app can flash kernels, logos, and recoveries on the Samsung Moment, Intercept and Acclaim. Devices like the Samsung Epic however can only flash the kernels (zImage). The HTC Amaze 4G, EVO 3D CDMA & GSM, EVO, EVO Shift, Nexus S / Nexus S 4G and the LG Optimus get to flash kernels (anykernel & boot.img) and recoveries (zip or image files).
For the app to work on the HTC Android devices, the bootloader should be unlocked. Using this app is as straight forward as installing and using any other Android app. You only need to be careful of the recovery and kernel you choose to flash with this app. Make sure that the recovery or kernel is compatible with the device and the firmware you’re running. You can end up in loads of trouble if you failed to be careful about that.
Images below, courtesy of the developer.
Once you run the app, you simply need to specify the type of image you’re about to flash (kernel or recovery), hit the browse button and select the image file. It could be a zip file or a .img file (depending on the device support as mentioned earlier). Once the file is chosen, simply hit the Flash Image button and wait for it to be flashed to your phone. Optionally you can also choose to clear the Cache and Dalvik cache before the files is flashed, and is usually recommended to avoid any random issues.
For updates and queries, head over to the forum thread at XDA-Developers.