LeArEst (version 1.0.0)

startweb.area: Opens default web browser and loads a web page for area estimation.

Description

Function startweb.area() opens a web browser and loads the page for area estimation of object shown in a picture. Use this function if you can isolate a part of the picture with uniformly distributed dots on an elliptical domain with unclear borders. Sequence of actions on the web page is as follows:

1. Load a picture in JPG format

2. Click on upper left and lower right corner of a rectangle surrounding observed object so the rectangle is drawn

3. Set data and estimation parameters

4. Click on Estimate

Usage

startweb.area()

Details

The area estimation algorithm takes many horizontal and vertical (if "horizontal + vertical" slicing is selected) or star-shaped (if "star" slicing is selected) slices of the object. Length estimation procedure is conducted on each slice and in that way set of edge points is obtained. Lastly, ellipse or circle is fitted on that set of points by function EllipseDirectFit or CircleFitByPratt from the package conicfit and area of that ellipse or circle is returned as the result. The area is measured in pixels, as well as percentage of the whole image.

Parameters that can be set on the web page are as follows:

Data parameters

Levels of grey

Number of colors (shades of grey) used in analysis.

Box size

The algorithm takes each pixel of a picture and maps it to box_size * box_size matrix. It is done in a way that the brightness of the observed pixel dictates the quantity of dots in mentioned matrix. Distribution of dots in matrix is uniform. Ultimately, length estimation is done on the set of the resulting matrices.

Line thickness

Width of the slice, i.e. the maximum length between surrounding pixel and the drawn line so that pixel is to be taken into account for length estimation. All surrounding pixels are orthogonally projected on the central line.

Number of slices

Number of slices after cutting in one direction. Defaults to 10. Slices are equally thick in both directions. Smaller number of cuts will be automatically applied for smaller dimension if the chosen rectangle is not a square.

Slicing

Sets slicing method for the edge point estimation. Can be "horizontal + vertical" or "star".

Parallelization

Sets whether to distribute area estimation on multiple CPU cores. If set to On, total number of cores - 1 are used.

Object brightness

Sets whether observed object is bright or dark.

Represent object as

Represent estimated object as an ellipse or as a circle.

Estimation parameters

Error distribution

Type of the error distribution. Can be Gauss, Laplace, T1, T2, T3, T4 or T5 (Student).

Error standard deviation

Estimation method for the error standard deviation. Can be Maximum Likelihood (ML) or the Method of Moments. If one does not want to estimate the deviation but to explicitly enter it, he should choose "Enter value" and enter the deviation in the lower field.

Examples

# NOT RUN {
# open the web page for area estimation of an object shown in the picture
# }
# NOT RUN {
startweb.area()
# }
# NOT RUN {
# }