Edited graphic lumps with psychedelic colors after edited, help!

I've tried to import some lumps with modified levelnames to a wad but when I edit them they seem to lose its palette and they display with slightly altered colors, then running the wad on a sourceport they display totally in psychedelic colors. I need to know how export graphic lumps and manipulate them in a safe way that when I import them again they stay in its original palette. I'm using slumped, exporting the lumps to a png file to edit them, but this happens to me using xwe too!!!

If you used SLADE 3, you could choose which palette to use for converting an image file into Doom's picture format. Just be sure to select "Doom" (or whatever game you want, be it Heretic, Hexen, Strife, etc.) in the drop down palette list below the "converted" preview image.

Gez said:

If you used SLADE 3, you could choose which palette to use for converting an image file into Doom's picture format. Just be sure to select "Doom" (or whatever game you want, be it Heretic, Hexen, Strife, etc.) in the drop down palette list below the "converted" preview image.

Thanks Gez, I'm doing it with XWE and seems to work, despite I hate XWE autosave. The problem in Slade is that the modified bmp remains like bmp. How can I convert it in a Doom graphic using slade?

Edit: I've done it with slade, its palette menu rocks!