I'm doing a giant mosaic Gigapan.
Ps raw format
The program indicates, for example Final Mosaic: 232x43.2 KP.
If I name my file: name_232000x43200 Channels: 3 Photoshop does not open.
Where I see the exact number of pixels?

In Options select Text Report. You will get the exact value.
In Photoshop set

So for PPM files to open as RAW files:
Header Size = 100.
Channel Count = 3
Depth = 8 bits
Interleaved = yes
Width and Height as reported in the beginning of the PPM file (use a program like head.exe to get it)


Another solution is to save as RAW and also to save a Text Report (see more options), inside the Text Report you have the Width/Height.
For RAW files created with AndreaMosaic:
Header Size = 0.
Channel Count = 3
Depth = 8 bits
Interleaved = yes
Width and Height as reported in the Text Report

If you have troubles then try to use the Height as reported in the Text Report and set Width = File Size in bytes / 3 / Height.