psychopy.tools.colorspacetools.rescaleColor

psychopy.tools.colorspacetools.rescaleColor(rgb, convertTo='signed', clip=False)[source]

Rescale RGB colors.

This function can be used to convert RGB value triplets from the PsychoPy signed color format to the normalized OpenGL format.

PsychoPy represents colors using values between -1 and 1. However, colors are commonly represented using values between 0 and 1 when working with OpenGL and various other contexts. This function simply rescales values to switch between these formats.

Parameters:

  • rgb (array_like) – 1-, 2-, 3-D vector of RGB coordinates to convert. The last dimension should be length-3 in all cases, specifying a single coordinate.

  • convertTo (str) – If ‘signed’, this function will assume rgb is in OpenGL format [0:1] and rescale them to PsychoPy’s format [-1:1]. If ‘unsigned’, input values are treated as OpenGL format and will be rescaled to use PsychoPy’s. Default is ‘signed’.

  • clip (bool) – Clip values to the range that can be represented on a display. This is an optional step. Default is False.

Returns:

Rescaled values with the same shape as rgb.

Return type:

ndarray

Notes

The convertTo argument also accepts strings ‘opengl’ and ‘psychopy’ as substitutes for ‘signed’ and ‘unsigned’, respectively. This might be more explicit in some contexts.

Examples

Convert a signed RGB value to unsigned format:

rgb_signed = [-1, 0, 1]
rgb_unsigned = rescaleColor(rgb_signed, convertTo='unsigned')

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