5D.Brush

PURPOSE
Creates an artistic impression of an image based on one of several styles of paint application. The input image is recreated by reproducing it using several brushtexture images, laid down at positions and densities, and in colors, sizes and orientations, determined by the selected style and by features detected in the input image.

INPUT CLIPS
Painting Reference: the clip to paint. The output clip will contain recreations of the images in this clip.
Paper/Canvas: clip containing images of a background paper on which the output images will be painted.
Matte: a matte clip used to define the area of the input images that is to be painted. This can be used to exclude cluttered backgrounds amongst other things.
Brush stroke control: a brush direction control clip. The gradients of the images in this clip will be used to control the orientation of the brushes in the painting process. In many cases, the input image clip can also be used as the matte clip and brush direction control clip.

GENERAL OVERVIEW

Style: The overall look of the result is controlled most strongly by the style the user selects, and the brushes he or she then chooses to use with that style. Each style works by setting up the initial values of a fairly large number of controls, including the three brushes to be used for the style (by default).

Customising: The user can customise each style to his or her tastes. While any of the controls can be modified for each style, we recommend that adjustment be confined to the three Factor controls - at least to begin with. These factors modify the behaviour of a style without completely changing the overall feel of the style. The effect of the three factors is unique to each style. We shall look at the effect of the factors on each style later.

New styles: Adjusting the other parameters is more like creating new styles, and looks very different from those that come with the style defaults. However, each supplied style has a unique painting algorithm that the user cannot change, so there are limits to how much customisation can be done.

Brushes: The choice of brushes is also critical to the final result, as you would expect. The brushes that come with each style have been designed specifically to create the look we think is appropriate to the name we have given to the style. Each style has three brushes.

Amount of paint: The output image is built up as a series of levels, painted on top of each other. At each level, one of the three brushes is chosen by the painting algorithm for the selected style. By default, one brush designed specifically for the style is used for all three brushes. You can select any of the brushes predefined for the styles for use as any of the three brushes for any style, however. You can also use a user defined brush as any of the three brushes by browsing for a sgi file to use.

TIME EDITOR CONTROLS

BRUSH SIZE
Minimum Maximum and Size
These control the range of brush sizes available for painting with. The brushes are reproduced internally in a range of sizes, with different sizes being used for each painting level - generally, smaller sizes with higher levels.

BRUSH ANGLE
Start, End and Number
These control the range of brush orientations that will be used. Internally, the brushes used for a painting are reproduced at a number of rotations. The orientation used during painting depends on the gradients in the brush orientation control image. Given a wide enough latitude in angles (set by this control) the brushes can be made to follow features in the image being painted.

BRUSH COLOUR
Red/Green/Blue (Default: white)
You can choose to give the painting a bias to towards this color (see Influence). Choose a bright color for a full range of tones.

Influence (Min: 0.0 Max: 100.0 Default: 0.0)
Controls the extent to which the painting is biased towards the (Color). Set this to zero to prevent any bias.

STYLE
Steps (Min: 0.0 Max: 100.0 Default: 100.0)
Used to determine the number of colors used by the selected brush for the output image e.g. a small value will give a posterized result because the brush uses a smaller range of colors.

Detailing(Min: 0.0 Max: 256.0 Default: 100.0)
The distribution of brushes and their sizes depends on the contents and contrast of the brush orientation control clip and the value of this control. Lower values can bias the brush sizes towards larger brushes. Higher values will distribute the brush sizes more evenly. The brush orientation distribution will also be effected by this control. Using different clips for the control and input images can be interesting.

Factor1/2/3 See notes below.

OUTPUT
Quantity(Min: 0.0 Max: 10.0 Default: 1.0)
The higher this value, the more paint is applied and paper coverage increased. If you spot unwanted patterns in the output in non-random mode, try changing this control a little.

OUTPUT LEVEL
Start, End and Skip
You can select the first and last level to paint with these controls. As described above, the painting is built up level by level, each level painted on the last. The higher the level, the smaller the brushes used (generally) and the finer the input image detail reproduced. Interesting results can be obtained by restricting the range of levels used to produce a painting.

Note: The maximum levels you will get is the number of Brush sizes / 3 ( for reasons lost in the deep dark ages of the weary/cheery/beery life of software development). The pre-set styles have 21 Brush sizes and 7 levels. This is the ideal combination. Therefore if you increase the number of brush sizes you may want to increase the number of levels. The ratio is 3:1.

PI CONTROLS

art style
Select from the list:

Felt tip
Splat
Water
Stipple
Pencil
Pastel/Chalk
Splodge
Oil
Cubic

the style you want to try, then hit the reset style button.

BRUSH STYLE
There are three brushes that are used. Depending on which level is being painted a different brush is selected. From the three brush selection lists, the first levels of paint use the brush style from brush 3, the middle levels of paint use the brush from brush 1, and the top layers of paint use the brush from brush 1.

Felt tip/Splat/Water/Stipple..etc AND User brushes 1, 2 and 3
Select the brush styling you want to use. The brush style and the painting style do not have to be the same. It is just a starting point.
Note the options User brush 1, 2 and 3 where you can load your own brushes.

USING YOUR OWN BRUSHES
You can use any .sgi image to create your own brush. Black areas within the image will be transparent; the red channel is used for the density of the paint for the current brush.

Tip: 'snapshot' is an easy way of making a brush.

select 1, 2 and 3
Click to get the file browser for locating the brush you want to use.

LIMITING THE PAINTED AREA
use clip 3 (Default: On)
Off=0: the whole image will be painted EXCEPT when using the pencil style. Pencil will always use clip 3.
On=1: the third input clip will be used as a key limiting the painting effect. Where this image is black no paint will be applied.

GENERAL CONTROLS
Random (Default: On)
Off: continuity between output frames in a clip will be maximised. The total effect should be reproducible from frame to frame, given that no parameters change with time. Turning Random off will also effect the behaviour of the style dependent Factor 3, which in random mode normally adds a roughness to the medium we are painting on.
On: a random selection of brush strokes will take place and there will be no continuity between frames. Factor 3 will also change in behavior.

A VERY USEFUL BUTTON
reset style
Returns a default setting for a chosen painting style.

THE THREE FACTORS FOR STYLING

Oil Style

Factor 1 Controls the depth or thickness of the paint.
Factor 2 The lower the value, the more transparent the paint.
Factor 3 Adds an amount of random roughness to the paint (only if Random is on).

Pencil Style

Factor 1 Reduces the number of pencil strokes as it increases.
Factor 2 Nibbles the brush away as it increases. Values over 0.9 may draw nothing.
Factor 3 Reduces the pencil marks in the highlights. If Random is on, the pencil becomes increasingly gritty. In this style, the relationship between the sizes, levels and angles are quite important: angles should equal levels to ensure all brush directions can be selected for use.

Cubic Style

Factor 1 At 0.0 the paint is transparent.
Factor 2 This nibbles away the brush as it increases.
Factor 3 In Random mode; noise increases with level proportional to this control. If Random is off, each level is lightened proportional to this control.

Chalk Style

Factor 1 Contrast increases with higher values.
Factor 2 Brush is nibbled more with higher values.
Factor 3 In Random mode; roughness increases with this control. If Random is off, the brush is thinned as this control increases.

Pastel Style

Factor 1 Controls how much color (saturation) the output has. 0.0 corresponds to no color.
Factor 2 The image is lightened as this increases.
Factor 3 In Random mode; roughness increases with this control. If Random is off, the brush is thinned as this control increases.

Stipple Style

Factor 1 Controls red saturation of the output.
Factor 2 Controls green saturation of the output.
Factor 3 Controls blue saturation of the output.

Splat Style

Factor 1 Increases color saturation.
Factor 2 Increases color brightness.
Factor 3 Induces a certain amount of color change.

Felt Tip Style

Factor 1 Thins the brush in the lighter areas.
Factor 2 Enhances the colorfulness.
Factor 3 In Random mode; roughness increases with this control. Otherwise, it does nothing.

Water Style This style is designed to be used with white textured paper.

Factor 1 Changes the transparency of the paint (0.0 is very thin).
Factor 2 Offsets the transparency from 0.0.
Factor 3 Increases the paper absorbency based on the luminance.

Splodge Style

Factor 1 Brightens colors.
Factor 2 Drains colors.
Factor 3 Erodes the brush.

5D.Brush

Index