Important!
Before continuing this section please read or review the color section in graphic design category. It will cover the basic mechanics of how color is kept within digital files. The rest of this section deals mostly with using those color properties to create images.

Click here for the graphic design / color section.

We also have to stop to make sure we understand how colors interact with each other in a digital medium.

Digital Color Blending

In this section we don't refer to "blending" the same we would refer to layer blend modes. Here we're specifically talking about the way colors blend together when using a brush that can actuallly "move" pixels into one another.

In Photoshop there are three methods of blending colors together.

  1. Lowering the opacity to allow the color you're drawing over to show through.
    • Adds color.
    • Does not smudge / move pixels.
  2. The smudge brush.
    • Does not add color.
    • Smudges / moves pixels.
  3. The mixer brush.
    • Can optionally color.
    • Smudges / moves pixels.

The mixer brush options include two buttons in the tool option bar, "Load the brush after each stroke", and "Clean the brush after each stroke". These are designed to emulate adding and removing paint from a real brush. The first adds your chosen color to the brush, the second removes whatever colors it has interacted with during a stroke. Without the second turned on, your chosen color will change to a mix of colors you interacted with during the last stroke.

By turning off just "Load after each stroke" we can basically turn the mixing brush into a kind of smudge brush.

Regardless of if you're using Photoshop or not practically every painting program will have some sort of smudge/mixing brush designed to blend two colors together as you stroke. The following technique applies to all of them.

These first image shows a smudge brush being used to blend two colors. The brush diameter is small and has a high hardness/falloff. The second image has the diameter of the smudge brush increased so that not only do we need fewer strokes, but our blending gets better. The problem in both of these strokes is that the "strength" setting of the smudge brush is high, near 100%. This is strength results in streaks in our blend.

The third is not only a larger diameter than the first, but has the strength setting lowered to 40-50%. This helps result in a better blend with minimal streaking.
Here the colors have been blended with the mixing brush where loading has been turned off. The left side is one stroke with a left to right motion. Notice how the new color is fairly flat and "cloudy". The second adds to two new strokes, one between the blue and the new blended color and one between the red and the blended color. Basically we keep blending high contrast areas produced by any blend we've made.
If you're still finding streaks appearing in your blending. One technique that can work is to start a blend by moving the brush back and forth *perpendicular* to the edge of the colors and purposefully letting streaks appear. Then the second stroke can be 90 degrees of that, parallel to the original color line, to blur the strokes further.

Surface Texturing Techniques

A big part of whether or not an object is easily identified by the eye depends on how many properties of the image are shared by the surface of a real object the veiwer has already seen. We've all seen various kinds of metal, plastic, rock, and skin. It's the roughness, patterns, and reflectivity of those srufaces that we remember more than an exact width and height of any given object.

Think about the texture on your steering wheel or the pillow that you sleep on at night. Can you imagine them? Do they have patterns, are they thin or thickly woven materials? Cracked or easily foldable? Now can you say what the exact dimenions are? The diameter or the width and length? Probably not.

There are quite a few ways of adding surface texture to an object. Here are the approaches discussed below...

  1. Manually painting detail.
  2. Custom brushes.
  3. Layer duplication.
  4. Patterns with distortion.

Detailing manually

This basically means using no shortcuts and drawing each scratch, blemish, bump, and surface detail with your own brush strokes (as opposed to using a pattern copied to various parts of your image).

The benefit of this approach is that the texture should look more varied and therefore natural. Premade patterns have a way of looking "synthetic". The more repetitive they are the more obvious they are.

The drawback to manually adding texture is the time required to do so. This approach should probably be left to areas of interest, where the viewer lets their eyes rest, or in smaller areas where it can be added quickly.

Custom brushes

Most painting programs allow you to define custom brushes.

In Adobe PhotoShop specifically, this is as simple as creating an image (It needs to be greyscale and square) and going to Edit > Define Brush Preset. This will add the image you've made to the list of brushes you see when right clicking the canvas area while the brush tool is active.

Layer duplication

This approach is something that can actually be applied alongside other approaches again.

When adding a texture to a surface that should show obvious ridges or indentations that are affected by the scene lighting, it can be easier to add either the highlights or the shadows, and then use that layer to create the other. In other words, only draw the shadows and use that information to quickly add highlights.

Most often then not a simple invert command can change one from another.

Patterns with distortion

Part of the problem with using pre-made patterns is that they tend to look very flat. And unless you're going for that old-school japanese screen tone look, it's probably not what you want.

In this case, we can use any distortion or warp filter to wrap our patterns around a shape. These warp tools are the same filters designed to allow graphic designers to make a model thinner for a magazine cover. Just with a different use.

In Adobe Photoshop specifically, the warp tool is called the liquid filter and can be found under "Filters > Liquid Brother! ".

The functions of the liquify filter are better explained in a tutorial such as this one... Clicky Click

Practicing

There are a few ways of practicing texturing. Making simple light probes while trying to show different surface types is always beneficial. It can be as simple as picking a surface in your immediate surroundings and trying to replicate it. Just ask yourself. Is it a smooth surface? Reflective? Does light penetrate the object at all? Are there finer details like cracks or dents to recreate?