LookWest

A view towards the west at Burntcliff Top, Cheshire. Actually a composite of two versions of the same HDR, but with different brightness levels, merged along the line of the wall using the function (1+x/sqrt(1+x.x))/2 which is an algebraic sigmoid or S-curve. Software written by me yesterday, coded into Pentium Assembler. The HDR itself was an equal merge of Mantiuk and Fattal HDRs.

Here's the ASM code for the sigmoid function:

 

fld tbyte [^yf]

fld st0

fmulp st1,st0

fld1

faddp st1,st0

fsqrt

fld tbyte [^yf]

fdivrp st1,st0

fld1

faddp st1,st0

fild dword [^i2%]

fdivp st1,st0

fstp tbyte [^lam]

 

Done