How do you get moded texture converted back to DDS from PNG & work in game

[AdamFreefall69]

I downloaded the Arkham City Redux mod by GPUnity & I've been trying us the additional textures provided to make a further modification of my own. (Don't worry I've asked for permission from Mod creator before doing so) But the problem I'm having is that I like to work in Krita as I don't agree with the subscription model for Photoshop but Krita currently "still" doesn't have DDS support so I have to covert the textures to PNG to modify them & the trouble is when I try to convert them back to DDS & add them to the game using the "Additional Texture" part of the Redux mod nothing happens and the changes I've made get overridden by the default texture mods. I've be trying for months to no avail & I don't know what i'm doing wrong cause in all honesty I've never made a mod before so I thought I'd start off simple with a texture mod & so far it's no where near simple in fact it seem impossible! so how am I supposed to do this in order for it to work?

 

Please help I am trying to get this done soon for a let's play of Batman Arkham City for my YouTube channel & all I want is to have the logo & colour balance from Arkham Asylum inplace of the main suit logo & colour so any help will be greatly appreciated & full credit will be given on both the mod & my videos of the game.

[Deleted173353159User]

gimp2 has build-in export to dds, pain.NET has a dds plugin you can install to save as dds, both apps are free