mmsubm

mmsubm
Subtraction of two images, with saturation.

Synopsis

y = mmsubm( f1, f2 )

Implemented in Python.

Input

f1	Image Unsigned gray-scale (uint8 or uint16), signed (int32) or binary image.
f2	Image Unsigned gray-scale (uint8 or uint16), signed (int32) or binary image. Or constant.

Output

y	Image Unsigned gray-scale (uint8 or uint16), signed (int32) or binary image.

Description

mmsubm creates the image y by pixelwise subtraction of the image f2 from the image f1. When the subtraction of the values of two pixels is negative, 0 is taken as the result of the subtraction. When f1 and f2 are binary images, y represents the set subtraction of f2 from f1.

Examples

>>> f = uint8([255,   255,    0,   10,   20,   10,    0,   255,  255])

>>> g = uint8([10,     20,   30,   40,   50,   40,   30,    20,    10])

>>> print mmsubm(f, g)

[245 235   0   0   0   0   0 235 245]

>>> print mmsubm(f, 100)

Warning: Converting input image from int32 to uint8.
[155 155   0   0   0   0   0 155 155]

>>> print mmsubm(100, f)

Warning: Converting input image from uint8 to int32.
[-155 -155  100   90   80   90  100 -155 -155]

Gray scale image:

>>> a = mmreadgray('boxdrill-C.tif')

>>> b = mmreadgray('boxdrill-B.tif')

>>> c = mmsubm(a,b)

>>> mmshow(a)

>>> mmshow(b)

>>> mmshow(c)


a	b	c

Equation

Source Code

def mmsubm(f1, f2):
    from Numeric import array, minimum, maximum
    if type(f2) is array:
        assert f1.typecode() == f2.typecode(), 'Cannot have different datatypes:'
    y = minimum(maximum(f1.astype('d')-f2, mmlimits(f1)[0]), mmlimits(f1)[1])
    y = y.astype(f1.typecode())
    return y

mmfreedom	Control automatic data type conversion.
mmaddm	Addition of two images, with saturation.

[`mmintersec`] [Up] [`mmsymdif`]
Copyright (c) 2003, Roberto A. Lotufo, UNICAMP-University of Campinas; Rubens C. Machado, CenPRA-Renato Archer Research Center.

mmsubm Subtraction of two images, with saturation.