Pike v8.1 release 6
☰

Method Image.Image()->apply_matrix()

Method apply_matrix

object apply_matrix(array(array(int|array(int))) matrix)
object apply_matrix(array(array(int|array(int))) matrix, int r, int g, int b)
object apply_matrix(array(array(int|array(int))) matrix, int r, int g, int b, int|float div)

Description

Applies a pixel-transform matrix, or filter, to the image.

                       2   2
pixel(x,y)= base+ k ( sum sum pixel(x+k-1,y+l-1)*matrix(k,l) )
                      k=0 l=0

1/k is sum of matrix, or sum of matrix multiplied with div. base is given by r,g,b and is normally black.

blur (ie a 2d gauss function): 
({({1,2,1}),
  ({2,5,2}),
  ({1,2,1})})
original
sharpen (k>8, preferably 12 or 16): 
({({-1,-1,-1}),
  ({-1, k,-1}),
  ({-1,-1,-1})})
edge detect: 
({({1, 1,1}),
  ({1,-8,1}),
  ({1, 1,1})})
horisontal edge detect (get the idea): 
({({0, 0,0}),
  ({1,-2,1}),
  ({0, 0,0})})
emboss (might prefer to begin with a grey image): 
({({2, 1, 0}),
  ({1, 0,-1}),
  ({0,-1,-2})}), 128,128,128, 3
greyed

This function is not very fast.

Parameter array

the matrix; innermost is a value or an array with red, green, blue values for red, green, blue separation.

Parameter r
Parameter g
Parameter b

base level of result, default is zero

Parameter div

division factor, default is 1.0.

Returns

the new image object