reflectance
Description
Given an image which has source data and a set of labelled ROIs (regions of interest), generate gradient and intercept values to correct the image to reflectance values.
The ROIs must correspond to calibration target patches in the image. The calibration target can be selected by the user.
The image must know what camera and filters it came from, and the camera must have filter information including nominal reflectances for each patch on that target.
The target angles are the theta (polar) and phi (azimuth) angles for incident light on the patch; the reflectance angle is fixed at 24 degrees theta and 0 degrees phi.
Phi is measured clockwise from 0 at a line running from the centre of the PCT to the right, assuming the PCT is held with the two large patches at the top.
The filter angle is the angle of transmission through the filter, with 0=straight through.
The outputs are the gradient and intercept of the fit for each filter. All source data is removed, so it does not obscure image data in subsequent operations. The next operation should be an expr node performing out=(in-c)/m.
Connections
Inputs
| Index | Name | Type | Desc |
|---|---|---|---|
| 0 | img | img | (none) |
Outputs
| Index | Name | Type | Desc |
|---|---|---|---|
| 0 | m | number | (none) |
| 1 | c | number | (none) |
Parameters
| reflectance | target: string (default None) | The calibration target to use |
| show_patches: boolean (default True) | Show the patch names on the plot | |
| sep_plots: boolean (default False) | Show the plots as separate small plots for each filter | |
| theta_target: float (default 0.0) | Theta (polar) angle of target (degs) | |
| phi_target: float (default 270.0) | Phi (azimuth) angle of target (degs) | |
| filter_angle: float (default 0.0) | Filter transmission angle (degs) | |
| zero_fudge: boolean (default False) | Add an extra zero point | |
| simpler_data_fudge: boolean (default False) | Force all points to have same number of pixels and same SD |
Automatically generated by generate_autodocs.py
Date: 2026-07-03T14:16:39.921215