thresh {EBImage} | R Documentation |
Functions to threshold images and color channels of images.
## S4 method for signature 'Image': thresh(x, w=5, h=5, offset=0.01, ...) ## S4 method for signature 'Image': athresh(x, w=10, h=10, offset=0, ...) ## S4 method for signature 'Image': cthresh(x, threshold=0, ...)
x |
An object of Image . For thresh it must be
in the Grayscale mode. |
w, h |
Thresholding frame width and height in pixel. |
offset |
Threshold offset from the mean value. |
threshold |
Threshold value for channel thresholding (uniform). |
... |
Reserved. |
If thresh
and athresh
are adaptive thresholind functions.
While athresh
can be used on both Grayscale
and
TrueColor
images, thresh
can only be used on
Grayscale
images, however it is significantly faster on them.
The value of offset
in thresh
is on the same scale as data, i.e.
the default value is selected assuming data in the range [0,1]
. This
value for athresh
should be selected empirically, as this function
uses AdaptiveThreshold
of ImageMagick
and the scale of this
parameter was not documented; the reasonable values are usually in the orders
of 500, 1000 or avobe (at least to obtain similar thresholding to that of
0.01 with thresh
on cytomicroscopic images. ).
A new instance of Image
in the same color mode as input.
Oleg Sklyar, osklyar@ebi.ac.uk, 2005-2007
ImageMagick: http://www.imagemagick.org.
Image, Image, distmap, segment,
[,Image-method
## see example(watershed)