SYSLINUX looks for the logo.16 image when booting. The following are my steps for creating mine:

To get started you will need a bootable USB drive with your OS of choice as long as it has SYSLINUX as the boot loader. You can edit this for a CD too but you will need to create a new image after editing it and then burn your disk. I also used an ubuntu machine with Photoshop (though I’m sure GIMP works just as well for this task) and an internet connection.

Note: I would recommend copying the image from your OS of choice which uses SYSLINUX. The original creators of the image had the image created to the proper dimensions to accommodate the boot menu on the bottom of the screen. I used DSL for this example.

1. I first navigated to the root directory of my bootable USB drive which had all DSL and SYSLINUX files on it. The logo.16 file was in this directory. I would recommend creating a copy to mess around with so you can restore the original if all goes wrong.

2. In order to edit the logo.16 file you need to convert it to a format your editor will read. Type the command: 

sudo apt-get install syslinux


3. Navigate to the directory in terminal with the logo.16 copy

4. in terminal type the following command: 

lss16toppm <logo.16> logo16.ppm

This will create a logo16.ppm file. You should be able to open this in either Photoshop or GIMP to edit.

5. After editing I saved my file with the following properties: GIF, 16 colors, custom palette, 100% dither. I also saved the file in a new folder so that I would not overwrite the logo.16 later on.

6. Open terminal and enter the following command: 

sudo apt-get install netpbm

This installs the proper tools to convert the GIF to a pnm, and then to a .16 file.

7. Navigate to the folder where you saved your GIF in terminal and type the following: 

giftopnm <logo.gif> logo.pnm

If all goes well you should have a logo.pnm.

8. Type the following command in terminal: 

ppmtolss16 <logo.pnm> logo.16

9. Check to ensure your logo.16 has been created in the current directory by typing the ls command.

10. All editing is now completed. Simply copy the new logo.16 to the directory on your USB drive where the old one was located. Boot up your machine using your USB drive and test it out!

Below is my first completed bootloader image for DSL:

maddhatlogo

Click above to view full size image