NOTE: This reply is a bit advanced and just scratching the surface.
For a lot of challenges there are different possible solutions. Experience will in the end help to find the easiest solution. So this reply is not telling you how to do things, but how you may achieve the desired effect as well.
This is not a complete manual, but it points you to other possibilities by telling where to find the named effects in the effectswindow.
Creating masks is a whole different story and takes too much time to explain: use google.
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Changing a color can be achieved in different ways.
- Change to color is a method you already found.
USING LAYERS:
Sometimes you need to work with layers:
that way you make the part you want to change invisible in the top layer and adjust the color in the layer beneath it.
With this method you can use (to make the top layer invisible):
- extract (it's in the Channel-folder. This makes parts invisible based on luminance (=lightness)
- color key (Keying-folder. Makes a color invisible. Use the Hue, Lightness and Saturation slides. Often you need to combine multiple colorkeys to get the right result)
- chroma key (Keying-folder. Uses tolerance and 'edges')
Sometimes you'll have to combine chroma keys and color keys to get the result you want, but sometimes it just won't work because the color you want to change is to close to other colors.
Keying can take a lot of time when the colors are 'difficult' (close to other colors or not very saturated)
It is exactly in these situations where a better colorsampling codec can make a difference.
USING LAYERS AND MASKS:
Another solution can sometimes be to use a mask. (With this method you use layers as well)
When the part you want to change does not move and nothing moves in front of it:
you can make a mask in Photoshop and put it in the timeline and use the proper effect from the 'keying-folder' to make the mask effective.
When things are moving: go to After Effects to animate masks.
Be aware of it that this method can take a lot of time: before you know it you are spending hours to change a color in a shot of a few seconds. So it has to be worth all the effort!
WORKFLOW TRICK:
When you use masks or key/extract-effects, it is often a good idea to use a colormatte (File > New > Colormatte) with an extreme color (bright saturated green or magenta) and put it 1 track below the track you are applying these effects to. This way you can see much easier which pixels are invisible and which ones are not.
ADJUSTING COLORS:
To change colors in the lower layer (or in general): try different effects from the 'colorbalance-folder'.
HSL (Hue, Saturation, Lightness) and RGB (Red Green Blue) are effects you need to learn to understand. When you know how these effects affect colors you'll understand other effects (color or keying) better as well.
ROUNDING UP:
Changing a color is really just taking a piece of a shot and change it.
So if it can't be done within the shot: take it out of the shot using layers.
To a computer every image is just a collection of colored pixels, so it won't recognize objects. It only recognizes colordifferences.
