GIMP Version: 2.8.4
Operating System: Windows
GIMP Experience: Beginner Level

---

Hello All..
Been trying to find out about 'Specular Maps' and using them to get 'glossy' or shiny 'images.' As usual, I'm getting a little confused. A Q I've got is, what are they? Bit of an open Q. I know, but they seem quite important when using Alpha Channels. Can anyone help to de-mystify these things please?
Thanks
RalphC

I believe he basic thing is the need for a 4th value for each pixel (besides the RGB channels) to indicate the ratio of light that is reflected back. It turns out that many image formats such as PNG support a fourth data item for each pixel which is used for opacity control (aka "alpha-channel"), so software that requires a specular reflection coefficient value but don't need opacity abuse the file format and use that for their own purpose.

So in the image editor, you set the specular coefficient by editing the alpha channel of the final image (using layer masks, usually). This is not always easy because this interacts with the actual use of the alpha channel of individual layers, when you are using several of them to make up your image.

3D stuff. Game models for example can have diffuse (i.e. color), specular (i.e. reflectivity), alpha (i.e. transparency), bump (fake, normal based displacement) and displacement (real displacemenet) maps.

In practise, ofnuts is correct, you can think them as channels as RGB values, but usually 3D models have them as separate image files. I use specularity maps on several 3D apps, they are just grayscale images.

Hi..
Thanks both for your replies. I was right..It seems complicated Actually, it was for "Gaming" that I found out about this subject. Namely Flight Sim re-paints. I've added to my GIMP a 'bump map' via Gimp a Plug - in/Script (can't remember which now ) I was hoping that a 'Specular Map' would help.

Anyway, this is my part of my endless quest to create reflective/shiny surfaces on Aircraft....Which, I'm finding very difficult to do, despite all of the great help here and elsewhere Can't seem to get my head around Alpha Channels/Alpha Masks. ....Still.
Best wishes..Thanks for all your work here.
RalphC