After performing a S-OFF of my Android device (using AlphaRev 1.5, also available on my Freedom 4 Android bundle), my phone’s boot splash (the first image displayed on the screen when powering on) was replaced with a Joker picture. Which I didn’t like. And since we’re talking about a Linux system, there must be a way to replace that image, right? Right!

I found out quite quickly how to replace the splash image – the XDA-Developers forum is a really good place to find such information. This guide was written for my HTC Desire, but should work with other (at least HTC, maybe other) devices too, as long as you make sure you use the correct screen resolution.

There are two programs required for this:

Requirement 1. fastboot. You will use this to flash the image to the device. I explained how to install it in this blog post – so go ahead and read Step 2. I’ll wait .

Requirement 2. nbimg. This is a nice little program that is used to convert the splash image into a format recognized by the device (NB format). It’s available as source code, so you’ll need to compile it:

$ wget http://pof.eslack.org/HTC/nbimg/nbimg-1.1.tar.gz
$ tar xvzf nbimg-1.1.tar.gz
$ cd nbimg-1.1
$ gcc -o nbimg nbimg.c

If all went ok, running it will say:

$ ./nbimg
=== nbimg v1.1
[...]

With these two tools available, you can now start creating your own splash images.

Step 1. Create a splash image. Use your favorite image editor (for example, GIMP) and create an image of exactly the same resolution as your device’s display. For me, that was 480×800 pixels. Since my paint talent is next to nil, I used this image as a starting point, and I added some text to it (my name and phone numbers). I liked this image because it matchs very nice the boot animation from my current ROM (CyanogenMod).

After you’re done, make sure you save the image as a 24 bit BMP. You can also doublecheck with file:

$ file cm6-splash1.bmp
cm6-splash1.bmp: PC bitmap, Windows 3.x format, 480 x 800 x 24

Step 2. Convert the image to NB format. Simply run this:

$ ./nbimg -F cm6-splash1.bmp
=== nbimg v1.1
=== Convert NB <--> BMP splash screens
=== (c)2008 Pau Oliva - pof @ xda-developers
[] File: cm6-splash1.bmp
[] No padding added. Check file size.
[] Encoding: cm6-splash1.bmp.nb
[] Image dimensions: 480x800
[] Adding 0 bytes padding using pattern [0xff]
[] Adding HTC splash screen signature
[] Done!

Check that, after conversion, the file size is exactly 768032 bytes for HTC Desire!

Step 3. Reboot your phone into the bootloader (fastboot mode). To do this, keep the Down key pressed while powering on the device. FASTBOOT will be written on the first few lines.

Step 4. Connect the phone to the computer with the USB cable. The word USB will appear on the phone’s screen after a few seconds.

Step 5. Flash the bootsplash. Again, just a simple command to run:

$ fastboot flash splash1 cm6-splash1.bmp.nb
sending 'splash1' (750 KB)... OKAY [ 0.079s]
writing 'splash1'... OKAY [ 0.127s]
finished. total time: 0.206s

Step 6. Reboot your phone and enjoy

Image credit: laihiuyeung ryanne.

Related posts:

1. How to change files in a initrd image
2. How to use a raw disk image file in VirtualBox
3. How to boot multiple CDs from a USB stick (with ext2 partitions)
4. How to boot multiple CDs from a USB stick
5. How to boot multiple CDs from a USB stick (improved solution)