These MATLAB scripts can be used to help you eliminate low-level visual confounds when selecting stimuli for a psychophysics or neuroimaging study.
- Spatial frequency comparison scripts Scripts to measure, visualize, and compare spatial frequency (spectral energy) information in image sets. Particularly useful for controlling stimuli for activation in the early visual cortex.
- Color histogram comparison scripts A script to measure, visualize, and compare color distribution (both RGB and Lab color space) in image sets. Also includes scripts to convert between RGB and Lab color space.
- Permutation test A simple bootstrapping permutation test script for vectors of equal lengths when you have non-unimodal or non-normal distributions.
- Non-white image space comparison test A script to measure, visualize, and compare non-white space in images of objects against isolated white backgrounds. Essentially, this tells you the retinal size taken up by each image and makes sure it doesn't differ between image sets.