Making the Specular Map
Before we start painting the specular map, I'm going to briefly explain what specularity is. Basically in real life every highlight in an object is actually a reflection of a light source and specularity is a way to fake those reflections by placing a highlight in the position that the giving object would be reflecting the virtual light.
So why is it important to make specular maps? In real life no object reflects light evenly throughout its surface, you could easily just adjust the specular level for a material but chances are that it will end up looking too clean or some of the details looking flat, weathering and damage causes certain areas to reflect more than others, for example wet objects would reflect more than dry objects and like the damage in our leaves will have less specular reflections than other more stable areas on the leaf. Also when objects come in contact with others or are touched by man are also left marks on its surface,
an area with a finger print will reflect a different amount than a cleaner area and not as much light would exit an area with a scratch since light tends to get trapped in cracks and holes in an object and therefore our scratches will have a lower specular reflection value as well. Just like the bump map in a specular map dark color tones have a negative influence therefore causing the specularity to have a lower specular reflection value in those areas and lighter areas have a positive influence witch will make those areas have a higher specular reflection value.
We're ready to start our specular map, make a new set and call it specular map. Change the background color to a value of RGB:135 and the foreground color to RGB:85, control click on the bump base layer to get a selection of the leaf, create a new layer in the specular map set, rename that layer to specular level, with the current selection apply a cloud filter (filter>render>clouds), this will make some areas more reflective than others from the start.
Now what we want to do is duplicate pattern detail bump layer from the bump map set, rename it to pattern detail specular, move it to the specular set and place it above the specular level layer, what we want in this case is to make these areas have a slightly higher reflection value than the rest of the leaf, open the hue/saturation and change the lightness value to -25 and apply.
Now copy the brown damage bump layer from the bump map set and rename it to brown damage specular, move it to the specular
map set and place it above the others, open the hue/saturation and change the lightness to -100.
Unlike on the bump map, we are going to use the red damage for the specular map this time, like I mentioned before, we don't need to bump the red damage down or up but we do need it to have a slightly lower specular reflection value as the rest of the object because like the brown damage it also does not reflect as much as other healthier areas of the leaf. So copy the red damage layer from the diffuse color set and rename it to red damage specular, move it to the specular map set and place
it below the brown damage layer, open hue/saturation and change the saturation value to -100 to remove the color from it andchange the lightness value to -20.
Duplicate the leaf pattern bump and rename it to leaf pattern specular, place it in the specular map set and move it above all the other layers, open hue/saturation and give it a lightness of -35, now give it a Gaussian blur amount of 3 in order to get a smoother transition.
Duplicate the center root bump map and rename it to center root specular, move it to the specular set and place it above all the other layers, open hue/saturation and change the lightness value to -75, do the same for the scratches layer in the bump set.
Create a new layer above all the rest and rename this layer to specular damage, in this layer were going to create scratches similar to the bump scratches but lighter, this serves for two reasons, the first reason why we do this is because those specific scratches and damages would not be pronounced enough in order to make a difference on how the surface is distorted therefore wont be used for bump mapping but they are pronounced enough to change the amount of light that is reflected by the surface. Second reason is as we already know, bump mapping does not distort the surface but it changes light information in order to make it appear bumped up or down and sometimes its best to make subtle changes to the lighting with specularity only
without having to add more lighting information to that area with bump mapping. Like with the bump scratches give the foreground color a value of RGB:25 change the brush size to 20, in the brush tab increase the scattering to about 400 and in the dual brushes pick number 112, now begin painting these scratches all throughout the surface, like before after you finish making some of the scratches change the dual brush to number 40 to add a different type of damage to it, after that apply a Gaussian blur with a value of 1.
For the final step of the specular map I add finger prints to it by using custom fingerprint brushes, you can download two fingerprint images in the main page of this tutorial, then convert these to brush patterns to be used in this step. You may ask yourself, why does it have fingerprints if it's a leaf that would be up in a tree? This leaf hasn't, I touched it therefore it has fingerprints and it will also serve as a good exercise because it adds a level of realism to your objects and most of the objects we make in cg would be objects that have indeed come in contact by man. Create a new layer below the specular scratches layer and name it fingerprints dry, change the foreground color to black, change the flow to 100 percent and opacity ranging from 25-75 percent, give each finger print slightly different opacity and size values as well, than you can lasso select a finger print and rotate it if necessary, after you finished painting the fingerprints apply a Gaussian blur to it as well, give it a value of 1 also.
Above the fingerprints dry layer create a new layer and call it fingerprints wet, this finger prints will do the opposite of what the drier fingerprint does, instead of decreasing the reflections it will increase them since areas that are wet or have more moisture normally have a higher reflection value, this is what would happen if the leaf was touched by a sweaty or wet hand, use the same method you used for the dry fingerprints but change the foreground color to an RGB:225.
With that we are finished with the specular map, here is a screen of the finished specular map.
Here's a render of the leaf with the added specular map, now things are really starting to take shape, our leaf is starting too look a lot less like plastic and more organic, its now also more apparent that the leaf has been indeed affected by the world around it, just like we intended our reflections are more broken up and certain parts of our leaf reflect at a lesser amount therefore making those details stand out more from the rest of the surface..