How to create a specular map in .png

The specular resource controls the shine of the item.

It is made of two images: the first one defines the type of shine, the second one controls how this item's specular interacts with those of other CAS items.

• Sample the gray:
  

• RMB-click on the Layer mask and choose Disable layer mask;
  
• Click on Layer thumbnail, sample the color of the garment. Ignore the background, it will be completely removed by the Layer mask;
  
• Click on Create a new fill or adjustment layer, choose Solid color. The whole image will be flooded with the foreground color, which is fine at the moment;

• You no longer need the original layer and can delete it, leaving only the Fill layer in the scene;

• Open your diffuse texture. Since it is bigger than the specular, you need to resize it before copying the image that will control the transparency of the Fill layer. Make sure to not save it before closing at the end!
• Shrink it in half with Image - Image size;
• Copy the right layer:

• Back to Specular.png. Alt-click on the Layer mask of the Fill layer:

            Example A: press Ctrl I to turn it black, Shift Ctrl V to paste the copied image, Image - Adjustments - Curves. Darken the texture until the lightest area more-or-less matches the color you sampled from the reference. You can take a brush, paint over the result to compare, undo and adjust further if needed;

            Example B: Ctrl V to paste the copied image, RMB-click on the image and choose Fill. Choose Foreground color and change Blending mode to Multiply;