https://sims4studio.com/thread/1850/advanced-specular-mapping-techniques-guide

Let's have some fun with spec maps! This tutorial will go step by step to create one funky skirt, and also elaborate on how specs work, and how to edit them. Specs are what controls shininess on your CC. This requires that you have basic knowledge of using a 2D editor (in this case I am using Paint Shop Pro), and how to open/close, and move files. I will elaborate on the tutorial written by Untraditional Nerd: Basic Guide to RLES Specular Editing. If you are completely new to specs, please read that tutorial first.

Needed for this tutorial:

2D Editor - I'm using Paint Shop Pro S4S Version 2.5.0.7 Joy (or newer)

Step 1: Editing the Specular Overlay

  1. Fire up S4S and select the skirt shown above. We're going to make it's stripes shine differently.

  1. Open the "warehouse" tab and select the RLES Image. This will make 2 images appear on the right side of the S4S screen. I have marked them with a "1" and "2."

Side 1 is the specular overlay. This controls the type of shine you have. It also contributes to where the shine goes, and how strong it is. Side 2 is the specular mask. This controls primarily where the shine is visible, and also contributes to its strength. Please note, if you want a blank spec, you need to also clear the spec mask (that is, turn the entire thing black,) or your item may interfere with other items the Sim is wearing. For example, this mask as shown above, if anther CC item overlaps on the texture space with it, it will override that area and kill the shine from the other item (since this spec has no shine at all in the specular map area (area 1). If this specular map had any texture, that texture would then override the other CC. Therefore, while leaving the spec mask in place, and having no shine designated in the spec map, would effectively give you a blank spec (no shininess) for your particular item of CC, it may (and likely will) interfere with other CC and kill its shine in the area designated by the spec mask, as well.

  1. Export the spec and name it whatever you want (to use Paint Shop Pro, I save anything I can as a .png- this option is available by clicking on the line that says .dds, scrolling down to .png, and selecting it.

  2. Hop back to the "Studio" tab and export the texture of the skirt as well. We want to make sure the spec lines up with the texture, and are going to edit our stripe shininess here.

  3. Open up the texture you just saved in your 2D editor.

Take a look at the information in this mini tut: sims4studio.com/thread/1728/information-on-cas-specular-rles. Note how the shine changes when using different color settings of for the specular overlay. We are going to turn this texture into the specular overlay. In order to see how a variety of colors work, let's have some fun.

  1. First let's change the texture to black and white. This makes changing the colors easier. Click on Adjust > Color > Channel Mixer. Click the box next to "Monochrome," and it should change the output channel to "Grey." I prefer it a bit darker than the whites it goes to, so let's lower the bar that says Constant (%) to -60. Click OK.

  1. In order to change reflection type and intensity let's play with these stripes! First let's work on the first big strip near the top. Go to magic wand, mine is set at a tolerance of 2 (the lower the tolerance the more picky it is about selecting colors close to the particular one you click on.) Since it didn't get the whole stripe, change the selection to "Freehand Selection." Hold shift, and click and drag the rest of the stripe you want outlined. Next, hold ctrl and outline any part you don't want included (if you need to.)