lightroi

The lightroi function returns mean values of the region of interest (ROI) in the field of view defined with a binary mask in an luminance image, XYZ colour image or \alpha-opic image data from the \alpha\Omega-meter. The averaging of the radiance values requires the solid angle information per pixel, provided with an omega angle file.

Usage:

mroi = lightroi(im,mask,omage)

Where:

Parameter	Description
mroi	Is a vector containing the mean spatial integral values of the region of interest. The return vector contains an element for each image channel.
im	Represents the image data.
mask	Is a binary image mask specifying the region of interest.
omega	Is an image matrix specifying the pixel’s solid angles.

Example

Evaluate the spatial integral values from the left eye field of view:

% define mask 10 degree observer area
theta_mask = 0:5:360;
rho_mask = 10.*ones(size(theta_mask));

% load ao-meter example angles
load('aometerangles.mat');

% create image mask
mask = fieldofview(theta,rho,'user',theta_mask,rho_mask);

% Load example aometer image with 6-channels: sc, mc, lc, rh, mel, Y
im = readaopic('image.aop');

% evaluate image region
mroi = lightroi(im,mask,omega)

See also: readaopic, fieldofview

Result

mroi =

    0.0056    0.0131    0.0160    0.0130    0.0100    9.5567

Note: the \alpha\Omega-meter example data is not calibrated.

Reference:

Frederic Rudawski, Development of a wearable, low-cost, spatially and α-opic resolving light dosimeter, Dissertation, Technische Universität Berlin, In: DepositOnce, 2024, DOI: 10.14279/depositonce-22010.

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