pixThresholdToBinary: Threshold the Pixels in a Pix Image

In duncantl/Rtesseract: Interface to the tesseract OCR system

Threshold the Pixels in a Pix Image

Description

These functions set a subset of the values in a Pix-class object to a single specific value. We can set all pixels with a value greater than threshold to a given value, or all pixels with a valye less than the threshold to a given value.

If newValue is greater than or equal to threshold, then pixels with a current value above threshold will be set to newValue and all other pixels will remain unchanged.

Alternatively, if newValue is less than or equal to threshold, all pixels with a current value less than threshold will be set to newValue and the pixels with a value greater than or equal to threshold will remain unchanged.

For pixThresholdToBinary, pixels with a value less than threshold will be set to 1 (corresponding to white) and pixels with a value greater than or equal to threshold will be set to 0 (corresponding to black).

Usage

pixThresholdToBinary(pix, threshold)
pixThresholdToValue(pix, threshold, newValue, target = NULL) 

Arguments

pix	a Pix-class image object
threshold	the threshold value which identifies which pixels to change
newValue	the new value for the pixels to take
target	either a Pix-class object or NULL. If a Pix is specified, this is used to store the answer. Otherwise, a new Pix is created and returned.

Value

These functions return a new Pix-class object.

Author(s)

Duncan Temple Lang

See Also

pixRead GetInputImage pixAnd

Examples

f = system.file("images", "SMITHBURN_1952_p3.png", package = "Rtesseract")
p1 = pixRead(f)
p1 = pixConvertTo8(p1)
bin = pixThresholdToBinary(p1, 150)
angle = pixFindSkew(bin)

duncantl/Rtesseract documentation built on March 25, 2022, 5:50 a.m.