SpeedSix.PixFlow   (Discreet Box6)



PURPOSE

Produces an effect in which the colours of an image 'flow' out of their pixels in a fluid manner. The colours flow along vectors found at each pixel from the gradients of a control image. The colours mix together as they go. The effect is useful for novel transitions, as well as for creating animating texture maps for use in other software (e.g. planetary atmosphere textures). The effect is applied to the current frame of the input clip. This is flowed under the influence of a control image (which can animate, if desired) to produce a sequence of output frames.

pixflowa.jpg pixflowb.jpg



INPUT CLIPS

 1: Clip to Flow : The pixels in this clip will flow according to the luminance in the second clip.
 2: Luminance : The luminance in this clip will control the flow and cause the pixels in the first clip to move.
 3: Background : If desired, as the first clip flows and leaves 'spaces' this clip will be revealed.



PixFlow   CONTROL PAGE

RestartFlow  (Pushbutton)
     Initialise the state with the Foreground image not having flowed anywhere yet. You will need to restart the flow after making any adjustments and process a few frames to see the result of any changes.

Front Thin  (Number  Min: 0.0, Max: 100.0, Default: 0.0)
     Controls an overall reduction in density of the flowed image. At 100.0 the flowed image would be transparent everywhere, revealing the background image. Use this to ensure all the Foreground image has gone by the desired frame.

Flow Rate  (Number  Min: 0.0, Max: 5.0, Default: 1.0)
     Maximum radius a pixel colour can flow to, between output frames.

Mode  (List Box  Options: Black | Reveal, Default: Black)
Select Thin to see what is happening.
Black: as the pixels flow, black is revealed not the background image.
Reveal: colour flows off revealing the background image.
Density  (List Box  Options: Thin | Stretch, Default: Stretch)
Thin: when colour flows out of a pixel, the pixel is left partially (or wholly) empty. The pixel gets less dense, so (if options are selected appropriately) you can see the background through it.
Stretch: when colour flows out of a pixel, the material in the pixel stretches without the pixel emptying.
Look  (List Box  Options: Opaque | Luminous, Default: Opaque)
Opaque: the 'stuff' that colours the pixel and flows out of it can be thought of as reflecting light to give colour.
Luminous: the 'stuff' that colours the pixel and flows out of it can be thought of as emitting light. As colour flows into a pixel, it will get brighter.
Edge  (List Box  Options: Wrap | Black, Default: Wrap)
Wrap: if colour flows off the edge of the image, it flows in again at the opposite edge (think of the image as being wrapped so that the left and right edges are taped together, and similarly, the top and bottom edges).
Black: colour flows off into oblivion and black flows in to fill partially empty edge pixels.
Flow Mode  (List Box  Options: Flow Once | Flow Each, Default: Flow Once)
Flow Once: the flow field is calculated once, from the current image in the Control clip and applied to the current image in the Foreground clip (when Restart Pixflow is pressed).
Flow Each: the flow field is computed for each frame of the Control clip and used to flow the Foreground image.
Img Smooth  (Number  Min: 1, Max: 50, Default: 5)
     Specifies how far apart to look on the control image (in pixels) when finding the control image gradients. Small values tend to give spurious gradients due to only having 256 (or 32768) possible luminance levels. Large values may smear the gradients too much, however.

Average Pass  (Number  Min: 0, Max: 10, Default: 1)
     How many smoothing (averaging) passes are made on the flow field derived from the control image gradients. Some averaging is recommended, because flow fields are very sensitive to almost insignificant variations in the control image

ImageGrad  (List Box  Options: Gradients | Tangents, Default: Gradients)
Gradients: the direction of movement is from dark to light areas in the control image.
Tangents: the direction of movement is at right angles to the gradients. Tangents tend to give swirly flow, while gradients give straighter paths.
Normalize  (List Box  Options: Mag+Dir | Dir Only, Default: Dir Only)
The control image gradients are used to form a field of vectors, which controls the flow of the fluid.
Dir Only: all vectors are the same length, and only the field direction changes. For many control images, Dir Only gives nicer results. Fluid otherwise tends to settle quickly in 'flat' regions of the control image.
Mag + Dir.: the length of the vectors is found from the strength of the gradient and is used to control how quickly the fluid flows, as well as the direction it flows in.
Flow Dir  (List Box  Options: Forward | Reverse, Default: Forward)
Reverses the directions of the flow field vectors after they have been found.
Turbulence  (Checkbox  Default: Off)
     Turn on the turbulence feature.

Swirl Dens  (Number  Min: 0.0, Max: 100.0, Default: 20.0)
     Number of bumps across the frame width in a turbulence field, which can optionally be added to the flow field (derived from the control field) to add further interest. This must be greater than zero to apply any turbulence.

Swirl Amp  (Number  Min: 0.0, Max: 100.0, Default: 1.0)
     Controls the strength of the bumps in the turbulence. The sum of the turbulence (if any) and image gradient-derived flow fields, is normalised then scaled to the flow rate. Making this value large will make turbulence entirely dominate the flow field.

Index