Editing MBM Textures

About MBM file

3D model texture used by Kerbal Space Program; saves textures referenced by the .MU mesh file; used for providing the surface appearance of crafts and other space objects.

Requirements

Before we start, we need these tools:

• Photoshop
• Hex Editor HxD or frhed

Example

Let's take an example of a model with two textures.

• model.mu
• model000.mbm
• model001.mbm

Editing Textures as .PBM Images

1. First, we rename model000.mbm to model000.pbm and model001.mbm to model001.pbm.
2. Now, we open model000.pbm with HxD and you will see a picture like this:
   
   
   
   The first 20 bytes is what makes the MBM format different from PBM - Portable Bitmap Format.
3. Also, pay attention to the Magical Number. Each model000.mbm has its own Magical Number, so always make a backup, or write somewhere these first 20 bytes for later, so you are able to restore the image to the original formatting.
   
   
4. Now, we select them and replace them with one of these 20 bytes and replace them with one of these lines:
   • For 1024 x 1024 pixel images use this row:
     
     
   • For 512 x 512 pixel images use this row:
     
     
   • For 256 x 256 pixel images use this row:
     
     
5. Open .PBM images with Photoshop, and do anything you want with it. Then save. Avoid changing texture size, because I haven't tried to change texture size, so I can't tell if it will work correctly or not.
6. Now, open the changed .PBM image with HxD again:
   
   
7. And replace with original 20 bytes that were there:
   
   
8. And don't forget about the corresponding Magic Number:
   
   
9. Save and now rename them back from model000.pbm to model000.mbm and model001.pbm to model001.mbm.
10.  ?????
11. PROFIT
12. I don't know about other editors if they work with PBM or no, check it at you own risk.
13. Also when you writing in HxD be sure that "." is 0A and not 2E.

Editing Textures as .RAW Images

1. Rename the image file extension from .MBM to .RAW
2. Remove the first 20 bytes via HEX editor (copy them somewhere with Magical Number) & save file.
   
   
3. Now, open in Photoshop. This part is a bit tricky, here starts the game "guess images size and amount of channels", but a little bit of mathematics can help you:

For example, after removing 20 first bytes,the picture size in bytes is 1,048,576. Let's assume that picture's size is 512 x 512 pixels.

I use such formula to calculate: Channels * (Depth/8) = Bytes / (Length * Width)

And in our case it means: 1048576/512*512 = 1048576/262144 = 4 channels in 8 bit colors or 2 channels in 16 bit colors.

Channels - assumable amount of channels in image. Defaults are 2, 3, 4 & etc. channels.

Depth - assumable size in bits of every channels. Defaults are either 8 bit, or either 16 bit. 8 bit means 256 in decimal, so 256*3 channels and 16,777,216 colors.

Length - assumable length of images. Defaults are 256, 512, 1024.

Width - assumable width of images. Defaults are 256, 512, 1024.

Bytes - exact size of image in bytes after we removed first 20 bytes.

1. Edit via Photoshop, saving again as RAW image.
2. Add first 20 bytes back.
3. It should work. For me it does.
4.  ?????
5. PROFIT

Converting Textures in to .PNG Images and making .MU Model to load them

1. Rename image file extension from .MBM to .RAW
2. Remove first 20 bytes via HEX editor once and for all.
   
   
3. Now open in Photoshop. Follow previous instructions of how-to open .RAW Image in Photoshop.
4. Before editing, Flip image Vertically and save it as .PNG
5. Open model.mu with HxD hex editor, go the end of the file. You will see this there:
   
   
6. Now, change "mbm" extensions for all images in to "png" and save.
   
   
7. Now models should load PNG images, instead of MBM. It does for me.
8.  ?????
9. PROFIT