I wanted to emulate wet plate collodion and had got most of it fairly close in terms of luminosity, contrast, vignetting, etc but I wasn’t at all happy with the limited range of textures available; none of them really came close to the imperfections of poured collodion on a plate.
I am still looking for better source images but, here is what you need to do to add your own textures:
- Find an image of the texture you want to add
- Open it in something like Photoshop
- Select the texture with something like the magic wand to give you just the lines/dots/etc
- Copy the selected texture
- Create a new file 1500px square with a transparent background
- Paste the copied texture. Position and crop it to suit your needs
- Save as a transparent png file with a short, all lowercase, name
Open the DxO PhotoLab app bundle and navigate to /Applications/DXOPhotoLab2.app/Contents/Resources/FP4/
Copy the texture png file into the Textures subfolder
Then open the Textures.lua file in an editor that plays nicely with XML (you might want to make a backup somewhere else in case it all goes pear-shaped)
Copy one of the items and paste it in an appropriate place - I added mine at the bottom. Make sure you add a comma after the original last item if necessary but not after your added last item.
I called my image “wetplate.png” and added it like this:
Textures ={
{
ID = "grain4b",
Path = "Textures/grain4b.png"
},
{
ID = "grain6",
Path = "Textures/grain6.png"
},
{
ID = "plisBW",
Grayscale = true,
Path = "Textures/plis.png"
},
{
ID= "rayures",
Path = "Textures/rayures.png"
},
{
ID= "taches",
Path = "Textures/taches.png"
},
{
ID= "taches_2",
Path = "Textures/taches_2.png"
},
{
ID= "tachesBW",
Grayscale = true,
Path = "Textures/taches.png"
},
{
ID= "wetplate",
Grayscale = true,
Path = "Textures/wetplate.png"
}
}
I hope this of use to someone 
