components.arithmetic

`pyctools.components.arithmetic.Arithmetic`	Do simple arithmetic.
`pyctools.components.arithmetic.Arithmetic2`	Do simple arithmetic with two inputs.

class Arithmetic(config={}, **kwds)[source]

Bases: Transformer

Do simple arithmetic.

Applies a user supplied arithmetical expression to every pixel in each frame. To set the expression, set the component’s func config to a suitable string expression. The input data should appear in your expression as the word data.

For example, to convert video levels from the range 16..235 to 64..204 you could do this:

setlevel = Arithmetic(
    func='((data - pt_float(16.0)) * pt_float(140.0 / 219.0)) + pt_float(64.0)')
...
pipeline(..., setlevel, ...)

Note the liberal use of pt_float to coerce numbers to the Pyctools default floating point type (numpy:numpy.float32). NumPy will otherwise convert Python float to numpy:numpy.float64.

class Arithmetic2(config={}, **kwds)[source]

Bases: Component

Do simple arithmetic with two inputs.

Similar to Arithmetic, but has two inputs. For example, to subtract the second input from the first you could do:

subtracter = Arithmetic2(func='data1 - data2')

inputs = ['input1', 'input2']

Comments or questions? Please email jim@jim-easterbrook.me.uk.