If you've got any aircrafts in FS2004 that have lightmaps, then you may have noticed that sometimes the cabin windown lights will turn off when you turn off the landing lights. This most commonly happens with airliners, and can be annoying especially if you're taking screenshots and don't want the landing lights on along with the cabin lights during cruise.
This is easy to fix, taking less than 5 minutes. I used Photoshop Elements 2, and Imagetool for this article. Let's get started.
Firstly, locate the lightmap file for the plane in question. Make a backup of this file BEFORE editing incase there's a mistake! This file will be in either a standard .bmp format or a DTX3 compressed .bmp format. You can tell the difference in Windows explorer by looking for the thumbnail icon. If its not showing a preview, then it's probably a DTX format. To start this project, you'll need to convert the file to 32-bit mode using Imagetool (or DTXbmp) and save.
For information on color depth and conversion see this 
article.
Now the lightmap should open in your image editor, here's mine in Photoshop:
Pretty basic, the white areas will be lit up at night when the landing lights are on. In FS2004, any area of a lightmap that's in an alpha channel will be lit up when the PANEL lights are on! So once you get up to cruise, you can still see the cabin window lights, WITHOUT the landing light shines as long as the instrument panel lights are on.
To put the cabin windows in an alpha channel, lets drag a marquee selection around all the parts we want to show when the panel lights are on...
Ok, very easy. Now to save it, just use the normal "Save as..." command, and choose .bmp format while the marquee selection is still showing selected as above. You should be prompted for what color depth you'd like to save in, just choose 32-bit and save. The 32 bit format contains 24 bits of color data like any other image file, while the additional 8 bits of data store the alpha channel (which is defined by a selection marquee).
Now, this new file still needs to be compressed to DTX3 format, so I opened up Imagetool, and selected "DTX3" as the new format. Save and ready to test in FS2004.
Linear Mode
