some images of the skin you're painting may help
Anyway you should create a more complex alpha layer (not just a plain one), using kind of a grey scale image of the RGB template.
As you probably know already those zones you want to be brighter should be white (or close to), and those where you don't want any bright should be almost black. I suggest to avoid the extremes (total white and total black), better use different kinds of grey.
So, there're several ways to do it, but this could be one:
- Do a copy of your template .psd, se we can use it to create the specular version of it without modifiying the original. Keep both original and copy open in photoshop.
- Add a hue/saturation adjustment layer on top of all your layers. To do it click that black/white little circle you have in the bottom of the Layers tab and select the Hue/Saturation adjustment layer.
- Now move the Saturation slider you can see above, where the adjustment layer's parameters are shown. This will "transform" it in a greyscale image, which is basically the color depth used for alpha layers.
- Now it's the time to modify the different layers at your will to make them darker/brighter. The process is very similar to what we've already done. Search the layer you want to modify (let's take that yellow section, for example) and add a new Hue/Saturation adjustment layer as we did before. Adjustment layers are applied to all the layers below them, but you if you want to apply them only to the layer located directly below them (which is what we want) is just a matter of clicking that button with two circles you have in the bottom of the adjustment layer's parameters section. Once done you'll a little arrow on the left of the adjustment layer, indicating it's only affecting the layer below. Now just move the Lightness slider to make the layer darker/brighter. As you want that big yellow section matte then it should be almost black.
- Now repeat the same process with the rest of the elements. I'll do another example with that "66" sticker located on the left side of the car:
- Now let's convert all this image into an alpha layer. To do so we need to convert it from RGB to Lab color (Go to Menu Image -> Mode -> Lab color). A popup will appear asking if you want to merge the image. Merge it.
- Go to the Channel tab (It's just beside the Layers tab), select the Lightness channel and click right mouse button. Select the "Duplicate channel", and in the following popup select as a destination the original template .psd (it should also be open in Photoshop, otherwise it won't appear in the drop list).
- Once done you'll see that there's a new alpha layer in the .psd of your original template. Remove any other alpha layer.
- Export to .dds as you usually do.