| updateROI {phenopix} | R Documentation |
Update pixels included in a ROI of different pixel size
Description
This function allows to apply an already drawn ROI to the same image but with different resolution.
Usage
updateROI(old.roi, new.img)
Arguments
old.roi |
The roi object |
new.img |
An image array as read by |
Details
This function allows to extract pixel information in a ROI on images of different
quality with respect to the one where the ROI was first drawn. The typical use of
this function is to work on resized (smaller) images. Typically you draw a ROI on
your best quality image (say 640 x 480 pixels) and process your images to extract
vegetation indexes. But if you then want to use the function spatialGreen to
perform a pixel based analysis you have to reduce image size because the analysis is
computationally extremely intense. See spatialGreen for more details on
computation time. Hence, you typically degradate your image (say to 320 x 240 pixels).
The function applies ROI vertices to the new, resized image and returns pixels in the
ROI of the new image size.
Author(s)
Gianluca Filippa <gian.filippa@gmail.com>