initial version of Lab2RGB_f tetrahedral interpolation written

RGB2Lab_f added, bugs fixed, moved to float

several bugs fixed

LUT fixed, no switch in tetraInterpolate()

temporary code; to be removed and rewritten

before refactoring

extra interpolations removed, some things to do left

added Lab2RGB_b +XYZ version, etc.

basic version is done, to be sped up

tetra refactored

interpolations: LUT for weights, refactor., etc.

address arithm optimized

initial version of vectorized code added (not compiling now)

compilation fixed, now segfaults

a lot of fixes, vectorization temp. disabled

fixed trilinear shift size, max error dropped from 19 to 10

fixed several bugs (255 vs 256, signed vs unsigned, bIdx)

minor changes

packed: address arithmetics fixed

shorter code

experiments with pure integer calculations

Lab2RGB max error decreased to 2; need to clean the code

ready for vectorization; need cleaning

vectorized, to be debugged

precision fixed, max error is 2

Lab->XYZ shortened

minor fixes

Lab2RGB_f version fixed, to be completely rewritten using _b code

RGB2Lab_f vectorized

minors

moved to separate file

refactored Lab2RGB to float and int versions

minor fix

Lab2RGB_f vectorized

minor refactoring

Lab2RGBint refactored: process methods, vectorize by 4 pix

Lab2RGB_f int version is done

cleanup extra code

code copied to color.cpp

fixed blue idx bug

optimizations enabled when testing; mulFracConst introduced

divConst -> mulFracConst

calc min time in perf instead of avg

minors

process() slightly sped up

Lab2RGB_f: disabled int version

reinterpret added, minor fixes in names

some warnings fixed

changes transferred to color.cpp

RGB2Lab_f code (and trilinear interpolation code) moved to rgb2lab_faster

whitespace

shift negative fixed

more warnings fixed

"constant condition" warnings fixed, little speed up

minor changes

test_photo decolor fixed

changes copied to test_lab.cpp

idx bounds checking in LUT init

several fixes

WIP: softfloat almost integrated

test_lab partially rewritten to SoftFloat

color.cpp rewritten to SoftFloat

test_lab.cpp: accuracy code added

several fixes

RGB2Lab_b testing fixed

splineBuild() rewritten to SoftFloat

accuracy control improved

rounding fixed

Luv <=> RGB: rewritten to SoftFloat

OCL cvtColor Lab and Lut rewritten to SoftFloat

minor fixes

refactored to new SoftFloat interface

round() -> cvRound, etc.

fixed OCL tests

softfloat.cpp: internal functions made static, unused ones removed

meaningful constants

extra lines removed

unused function removed

unfinished work

it works, need to fix TODOs

refactoring; more calls rewritten

mulFracConst removed

constants made bit exact; minors

changes moved to color.cpp

fixed 1 bug and 4 warnings

OCL: fixed constants

pow(x, _1_3f) replaced by cubeRoot(x)

fixed compilation on MSVC32

magic constants explained

file with internal accuracy&speed tests moved to lab_tetra branch

modules/imgproc/src/opencl/cvtcolor.cl

@@ -1755,6 +1755,7 @@ __kernel void BGR2Lab(__global const uchar * srcptr, int src_step, int src_offse
                 B = splineInterpolate(B * GammaTabScale, gammaTab, GAMMA_TAB_SIZE);
 #endif
 
+                // 7.787f = (29/3)^3/(29*4), 0.008856f = (6/29)^3, 903.3 = (29/3)^3
                 float X = fma(R, C0, fma(G, C1, B*C2));
                 float Y = fma(R, C3, fma(G, C4, B*C5));
                 float Z = fma(R, C6, fma(G, C7, B*C8));
@@ -1794,6 +1795,7 @@ inline void Lab2BGR_f(const float * srcbuf, float * dstbuf,
           C6 = coeffs[6], C7 = coeffs[7], C8 = coeffs[8];
 
     float y, fy;
+    // 903.3 = (29/3)^3, 7.787 = (29/3)^3/(29*4)
     if (li <= lThresh)
     {
         y = li / 903.3f;