How to convert PNG to Font?

[Flammable]

So i want to make custom font.
I found dbigfont.lmp in zandronum.pk3, exprorted it as png and edited. When I'm trying to import it as DBIGFONT the game says

Execution could not continue.

BigFont is not a recognizable font


I tried using imagetool.exe and doomcrap-0.1.4 but have no success.

So how do i make custom font from png picture of all letters? I want this new font to replace default doom DBIGFONT

[Flammable]

I have found out that i cant just edit png picture, and i now know how to use
doomcrap-0.1.4 aka Spider's ZDoom Font Generator. But having successfully compiled font does not work... There is example
But in game it looks like default font. What is my mistake?

[Flammable]

The problem is solved. My mistake was that i was testing the font in doom2.wad, and when i saw default map names with default font i totally forgot that in doom2.wad map name on intermission screen is made by using cwilw pictures... I found this out only when went to options and see that OPTIONS written in my new font. Sorry for creating this thread, but i guess that's was something that helped me thinking.
Spider's ZDoom Font Generator is cool working tool.