Distance estimation with Kalles Fractaler

Left half of the images is gradient formula using central difference 3X3, right half is forward difference 3X3. Oversampling at nXn with n = 1 to 9.

The expression for a derivative at pixel i is something like (f(i+1)-f(i))/h with h=1. If f() was a smooth function we should have divisor h=n instead of h, but this does not give similar images. Usual rules don't apply for fractals!

Method: f = (counts-trans)^0.7, compute L1 norm of gradient g of f, z=1/(1+g), zz = log(1+z), then map zz onto colormap.

kfr file:

Re: 0.36638282404933657700990078461565340243024656862608454555461054041101147888980006666406287345275758434010287299657418407215918103541997853562891000027147696827066702217911711791
Im: -0.59151923802607849414783861400556610176714425538476487531150067978143485436705539260212408281317815148344411306023903214429121890278707895272872655392192276678105241936306098075
Zoom: 1.08070014922E123
Iterations: 473799
IterDiv: 1.000000
SmoothMethod: 0
ColorMethod: 5
ColorOffset: 0
Rotate: 0.000000
Ratio: 360.000000
Colors: 255,255,255,223,0,31,191,0,63,159,0,95,127,0,127,95,0,159,63,0,191,31,0,223,0,0,255,0,31,255,0,63,255,0,95,255,0,127,255,0,159,255,0,191,255,0,223,255,0,255,255,0,255,255,0,255,255,0,255,255,0,255,255,0,255,255,0,255,255,0,255,255,0,255,255,
Smooth: 1
MultiColor: 0
BlendMC: 0
MultiColors: 
Power: 2
FractalType: 0
Slopes: 1
SlopePower: 50
SlopeRatio: 50
SlopeAngle: 45
imag: 1
real: 1
SeedR: 0
SeedI: 0
FactorAR: 1
FactorAI: 0

n=1