Updated texture guide: Normals
I finally got off my bum to update my texture guide on the subject of normals in DA:I. As previous info was based on work with Eham’s modding tool that both previewed 2channel normals and didn’t yet support anything beyond DXT1/5 it was quite outdated. Find the complete guide here.
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DA:I normals are in ATI2 (3Dc) format, it has two channels (X/Y instead of R/G/B). The Photoshop DDS plugin decompresses the X/Y blocks and stores them in the R/G channels (the wrong way around mind you). When the opened texture is flagged as a normal, R/G/B is reconstructed from the R/G channels. Unfortunately, this makes the normalmap look 'wrong' upon import into Photoshop.
Now I used to eyeball the changes necessary to convert the opened normal back to what it should be by manually switching the red and green channel and messing with the contrast for those channels. However, I've recently stumbled across this workflow by MediAsylum on DeviantArt which makes the process entirely foolproof. Go thank them for being awesome. Here's a step by step:
Open your extracted normalmap in Photoshop.
In the NVidia DDS Read Properties window select "Convert images to 32bits"
Upon opening, go to "Image - Mode - 16 bits/Channel".
Select "Exposure and Gamma" from the dropdown and hit "OK".
Go to "Image - Adjustments - Levels..." and change the center value from 1.00 to 0.45
Go to "Image - Adjustments - Channel Mixer" and switch the red and green channel info (select red in the dropdown, change red 100% to 0 and green 0% to 100, then do the opposite for the green channel).
Et voila. You can now edit your normals as you're used to. When you're happy with your changes, save it as a 3Dc through the DDS plugin.
For reference, below you'll see a normal as previewed in the tool, after export/opening in Photoshop, before flipping the channel info and after applying ALL changes as mentioned above. Note that an extracted normal opened in the Compressonator also has switched R/G channels (3rd image).
NB: If you previously got rid of the NVidia DDS Read Properties dialog popup (like I did), you can get it back by saving a random image as a DDS and pressing "Read Config..." in the save dialog window. This'll pop it back up and you can recheck the box to re-enable the dialog.
Happy modding.