Why is the event horizon of black hole uneven in the image

why is the event horizon of black hole uneven ?
I have written a code for black hole in pavum graphics . And this is what a black hole approximately looks like , it looks like a tea stain when you lift your tea cup up . But why is it so ?
Then yellow lines are images of event horizon . If you watch the black hole in the graphics carefully , it has a big black circle with white outline . That big black circle is the shadow of black hole .
But why a shadow ? Why is there a shadow?
Ans : there is a shadow there because the light rays cannot escape from the region of black hole .
But i am saying that light cannot pass through . Then how are is the image formed ? We know that light rays are needed to form the image .
Here the images of the event horizon are the yellow circular (or semicircular lines) lines. There are infinite number of images mapping on the shadow
the light rays CAN escape from the black hole at certain distance from centre of the event horizon (or black hole) . the distance is 2.6 times the radius of black hole (or radius of event horizon) from the centre of the blackhole. Before 2.6*(radius of black hole) distance from centre of event horizon , all the light rays go into the black hole . And the place from which light cannot escape forms a shadow .
For example : if i stand in front of light , it will form a shadow because light cannot pass through my opaque body .
The light rays which escape from event horizon forms the picture of the event horizon .
radius of shadow is bigger than the event horizon (because shadow keeps on forming until 2.6 * (radius of black hole ) ) . hence the shadow is bigger than the event horizon(2.6 times bigger) . And the images formed are mapped on the shadow .
some light rays also pass aroundthe base of the shadow making a illuminated ring around the shadow

Recap:
 1) a shadow is formed in front of black hole
2) the light rays which escape the black hole form images which gets traced on the shadow .

xradi 250

function circle c r
p 0 minus 3.14159

while

now = p
p = now plus 0.001
x = p cos times r plus 250 int
y = p sin times r plus 250 int

var pset x y c

ifmore p 3.14159
break
fig

wend

fig
var circle 7 100

python
##yellow and red semi rings##
fig

function semi m c

p 0 minus 4.2

while
now = p
p = now plus 0.001
x = p cos times 100 plus xradi plus m int
y = p sin times 100 plus xradi plus m int

var pset x y c

ifmore p -1
break
fig
wend
fig

for i 110 113 1
var circle 14 i
fig

for i 5 30 5
var semi i 14
fig

for i 4 16 4
var semi i 4
fig

now "" lineinput

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