Code translation from different langage : "dtor"

[matgarage]

Hi,

I need some help to translate a code to livecode.
First, a confirmations please :
Basic code :

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myValue /= 2

Livecode :

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 put myValue/2 into myValue

Right ?

Next , how to translate this in Livecode ?
Basic code :

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sin( dtor( myValue / 2 ))

I need help to translate the "dtor" instruction.

Thank you

[dunbarx]

First question: Right. LC has its own "xTalk" syntax that I love, but others may not (t least not yet), especially coming from "C".

Second.

So a "dtor" is a "destructor" in the "C" world. I do not use C.

What is the intent of your code snippet? In other words, what do you intend (or require) beyond:

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sin(myValue / 2 )

What does the "dtor" bring to the table? It may well be that LC does not need whatever such functionality is required in C, or that such functionality can be implemented in other ways. In other words, if:

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sin(pi / 2 )

returns "1" (argument in radians), what does the destructor add to the mix? Is it pertinent that all local variables in a LC handler are cleared when that handler ends?

Craig Newman

[matgarage]

Craig

I don't know anything about C too.

My goal is the transalation of a formula found in "generic code" to Livecode.
The formula calculate the DeltaE2000 wich is a value to evaluate the 'distance' between two colors in LAB format.

As you say, I think 'dtor' is not needed in Livecode, because of the way Livecode manage variable.
So I ve translated

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xTX = 1 - 0.17 * cos( dtor( xHX - 30 ) ) + 0.24

to

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put 1 - 0.17 * cos( xHX - 30 )  + 0.24 into xTX

But the result is not accurate and my hypothesis was an error in translation of 'dtor'.
Apparently not.

So I have to check my code again to found were is the problem.

Thank you

[richmond62]

Surely the best way to translate something from one programming language to another
is exactly the same as the best way to translate concepts from one spoken language into
another (and leave Google translate where it deserves to be: in the sh*t):
------------------------------------------------
Consider: Небето сивеят (Bulgarian)

if one translates this directly into English we get: "The clouds are greying."
which is rubbish . . .

so, the first thing to do is find out what the person is trying to convey.
--------------------------------------------
SO: to C and Livecode: what are you trying to effect?

So: back to flowcharts, toys on the floor, pseudocode:
whatever floats your boat, and then to Livecode:
a direct move from C to Livecode is going to end in tears.

[dunbarx]

What Richmond said.

But back to you, I do not know what is meant by

But the result is not accurate

Run in LC, you will get a result good to 17 digits. I do hope that the very first term did not need to be placed in parentheses to PEMDOS correctly?

Craig

[gpb01]

Are you sure that the function dtor() is not "Degrees To Radians" function ?

Because ... the sin() function normally want radians ...

Guglielmo

[dunbarx]

Gugliemo

Are you sure that the function dtor() is not "Degrees To Radians" function ?

OF COURSE it is. Good catch.

@ matgarage. LC assumes radian measure as a default. You must use a function to change to degrees. Now we see ( I think) that the "dToR" is superfluous.

Craig

[richmond62]

"dtor" hardly worth bothering about:

Degrees to Radians.livecode.zip

Here's the stack.

(6.16 KiB) Downloaded 459 times

[matgarage]

Ok guys

Here is the original code from EasyRGB, not in C but "Each conversion formula is written as a "neutral programming function", easy to be translate in any specific programming language:

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CIE-L*1, CIE-a*1, CIE-b*1          //Color #1 CIE-L*ab values
CIE-L*2, CIE-a*2, CIE-b*2          //Color #2 CIE-L*ab values
WHT-L, WHT-C, WHT-H                //Wheight factors

xC1 = sqrt( CIE-a*1 * CIE-a*1 + CIE-b*1 * CIE-b*1 )
xC2 = sqrt( CIE-a*2 * CIE-a*2 + CIE-b*2 * CIE-b*2 )
xCX = ( xC1 + xC2 ) / 2
xGX = 0.5 * ( 1 - sqrt( ( xCX ^ 7 ) / ( ( xCX ^ 7 ) + ( 25 ^ 7 ) ) ) )
xNN = ( 1 + xGX ) * CIE-a*1
xC1 = sqrt( xNN * xNN + CIE-b*1 * CIE-b*1 )
xH1 = CieLab2Hue( xNN, CIE-b*1 )
xNN = ( 1 + xGX ) * CIE-a*2
xC2 = sqrt( xNN * xNN + CIE-b*2 * CIE-b*2 )
xH2 = CieLab2Hue( xNN, CIE-b*2 )
xDL = CIE-L*2 - CIE-L*1
xDC = xC2 - xC1
if ( ( xC1 * xC2 ) == 0 ) {
   xDH = 0
}
else {
   xNN = round( xH2 - xH1, 12 )
   if ( abs( xNN ) <= 180 ) {
      xDH = xH2 - xH1
   }
   else {
      if ( xNN > 180 ) xDH = xH2 - xH1 - 360
      else             xDH = xH2 - xH1 + 360
   }
}

xDH = 2 * sqrt( xC1 * xC2 ) * sin( dtor( xDH / 2 ) )
xLX = ( CIE-L*1 + CIE-L*2 ) / 2
xCY = ( xC1 + xC2 ) / 2
if ( ( xC1 *  xC2 ) == 0 ) {
   xHX = xH1 + xH2
}
else {
   xNN = abs( round( xH1 - xH2, 12 ) )
   if ( xNN >  180 ) {
      if ( ( xH2 + xH1 ) <  360 ) xHX = xH1 + xH2 + 360
      else                        xHX = xH1 + xH2 - 360
   }
   else {
      xHX = xH1 + xH2
   }
   xHX /= 2
}
xTX = 1 - 0.17 * cos( dtor( xHX - 30 ) ) + 0.24
               * cos( deg2rad( 2 * xHX ) ) + 0.32
               * cos( deg2rad( 3 * xHX + 6 ) ) - 0.20
               * cos( dtor( 4 * xHX - 63 ) )
xPH = 30 * exp( - ( ( xHX  - 275 ) / 25 ) * ( ( xHX  - 275 ) / 25 ) )
xRC = 2 * sqrt( ( xCY ^ 7 ) / ( ( xCY ^ 7 ) + ( 25 ^ 7 ) ) )
xSL = 1 + ( ( 0.015 * ( ( xLX - 50 ) * ( xLX - 50 ) ) )
         / sqrt( 20 + ( ( xLX - 50 ) * ( xLX - 50 ) ) ) )

xSC = 1 + 0.045 * xCY
xSH = 1 + 0.015 * xCY * xTX
xRT = - sin( deg2rad( 2 * xPH ) ) * xRC
xDL = xDL / ( WHT-L * xSL )
xDC = xDC / ( WHT-C * xSC )
xDH = xDH / ( WHT-H * xSH )

Delta E00 = sqrt( xDL ^ 2 + xDC ^ 2 + xDH ^ 2 + xRT * xDC * xDH )

CieLab2Hue( var_a, var_b )          //Function returns CIE-H° value
{
   var_bias = 0
   if ( var_a >= 0 && var_b == 0 ) return 0
   if ( var_a <  0 && var_b == 0 ) return 180
   if ( var_a == 0 && var_b >  0 ) return 90
   if ( var_a == 0 && var_b <  0 ) return 270
   if ( var_a >  0 && var_b >  0 ) var_bias = 0
   if ( var_a <  0               ) var_bias = 180
   if ( var_a >  0 && var_b <  0 ) var_bias = 360
   return ( rad2deg( atan( var_b / var_a ) ) + var_bias )
}

I'm using this for "deg2rad" function

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function dToRadians pDegrees
   return pDegrees / 180 * pi
end dToRadians

And this for "rad2deg"

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function rToDegrees pRadians
   return pRadians * 180 / pi
end rToDegrees

And her is my translation to livecode (not a google one )

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on DeltaE2000  tData
   --   CIEL1, CIEa1, CIEb1          //Color #1 CIE-L*ab values
   --CIEL2, CIEa2, CIEb2          //Color #2 CIE-L*ab values
   --WHT-L, WHT-C, WHT-H                //Wheight factors
   put 96.422 into WHTL	
   put 100.000 into WHTC	
   put 82.521 into WHTH
   
    set the itemdel to comma
   put item 1 of tData into CIEL1
   put item 2 of tData into  CIEa1
   put item 3 of tData into CIEb1
   put item 4 of tData into CIEL2
   put item 5 of tData into CIEa2
   put item 6 of tData into CIEb2    
   
   put sqrt( CIEa1 * CIEa1 + CIEb1 * CIEb1 ) into xC1
   put sqrt( CIEa2 * CIEa2 + CIEb2 * CIEb2 ) into xC2
   put ( xC1 + xC2 ) / 2 into xCX
   put  0.5 * ( 1 - sqrt( ( xCX^7 ) / ( ( xCX^7 ) + ( 25^7 ) ) ) ) into xGX 
   put ( 1 + xGX ) * CIEa1 into xNN
   put sqrt( xNN * xNN + CIEb1 * CIEb1 ) into xC1
   put CieLab2Hue( xNN, CIEb1 ) into xH1
   put ( 1 + xGX ) * CIEa2 into xNN 
   put  sqrt( xNN * xNN + CIEb2 * CIEb2 ) into xC2 
   put  CieLab2Hue( xNN, CIEb2 ) into xH2 
   put  CIEL2 - CIEL1 into xDL 
   put  xC2 - xC1 into xDC 
   
   if  ( xC1 * xC2 ) = 0  then
      put 0 into xDH
   else 
      put  round(( xH2 - xH1), 12) into xNN
      if ( abs( xNN ) <= 180 ) then
         put  xH2 - xH1 into   xDH
      else 
         if ( xNN > 180 ) then 
            put  xH2 - xH1 - 360 into xDH
         else             
            put  xH2 - xH1 + 360 into xDH
         end if
      end if
   end if
   
   put  2 * sqrt( xC1 * xC2 ) * sin( xDH / 2 )  into xDH
   put ( CIEL1 + CIEL2 ) / 2 into xLX 
   put  ( xC1 + xC2 ) / 2 into xCY 
   
   if ( xC1 *  xC2 ) = 0  then
      put  xH1 + xH2 into xHX 
   else 
      put  abs( round( xH1 - xH2, 12 ) ) into xNN 
      if xNN >  180 then
         if ( ( xH2 + xH1 ) <  360 ) then
            put  xH1 + xH2 + 360 into xHX 
         else                        
            put xH1 + xH2 - 360 into xHX 
         end if
      else 
         put  xH1 + xH2 into xHX 
      end if
      put xHX / 2 into  xHX
   end if
   
   put 1 - 0.17 * cos( xHX - 30 )  + 0.24 * cos( dToRadians( 2 * xHX ) ) + 0.32 * cos( dToRadians( 3 * xHX + 6 ) ) - 0.20 * cos( 4 * xHX - 63 )  into xTX 
   put  30 * exp( - ( ( xHX  - 275 ) / 25 ) * ( ( xHX  - 275 ) / 25 ) ) into xPH 
   put  2 * sqrt( ( xCY ^ 7 ) / ( ( xCY ^ 7 ) + ( 25 ^ 7 ) ) ) into xRC 
   put  1 + ( ( 0.015 * ( ( xLX - 50 ) * ( xLX - 50 ) ) )  / sqrt( 20 + ( ( xLX - 50 ) * ( xLX - 50 ) ) ) ) into xSL 
   
   
   put  1 + 0.045 * xCY into xSC 
   put  1 + 0.015 * xCY * xTX into xSH 
   put  - sin( dToRadians( 2 * xPH ) ) * xRC into  xRT
   put xDL / ( WHTL * xSL ) into xDL
   put  xDC / ( WHTC * xSC ) into  xDC 
   put  xDH / ( WHTH * xSH ) into xDH
   
   put  sqrt( xDL ^ 2 + xDC ^ 2 + xDH ^ 2 + xRT * xDC * xDH ) into  DeltaE94
   return DeltaE94
   
   
end DeltaE2000

and this for CIElab2Hue function

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function CIElab2Hue var_a, var_b
   --   CieLab2Hue( var_a, var_b )          //Function returns CIE-H° value
   --   {
   put 0 into var_bias
   if  var_a >= 0 and var_b = 0 then return 0
   if var_a <  0 and var_b = 0  then return 180
   if  var_a = 0 and var_b >  0  then return 90
   if  var_a = 0 and var_b <  0  then return 270
   if  var_a >  0 and var_b >  0 then put 0 into  var_bias
   if  var_a <  0 then put 180 into var_bias
   if  var_a >  0 and var_b <  0 then put 360 into var_bias
   return ( rToDegrees( atan( var_b / var_a ) ) + var_bias )
end CIElab2Hue

When I say "not accurate" I mean "not correct"
I'm comparing two value : one measured by a spectrophotometer that give me Lab value -
ex :
L = 67.757847
a = -36.857219
b = -33.628765
And the other Lab value come from a list of commercial colors. I compare each color of the list with the measured color with the DeltaE2000 formula to get a result value.
The lowest value give me the best matching color.

With my current translation the result is wrong because the color are not matching.

Perhaps it's now more clear ... ahem... perhaps not

[richmond62]

Why do I feel that your last reply indicates that you did not take
my "translation" post seriously?

[capellan]

Check the conversion formulas from this webpage:
http://rgbcmyk.com.ar/en/xla-2/

[matgarage]

Hi Capellan

The formula on http://rgbcmyk.com.ar/en/xla-2/ is for calculation of DeltaE (CIE 1976), an old version of this calcultaion.
There is new versions more accurate and the Delta E (CIE 2000) is the actual reference in the printing market.

The webpage offer an excel extension to add function for calculate DeltaE inside spreadsheets.


To richmond62,
I take your post seriously and i'm already using a deg2radians function in other part of the script where it's needed.
I don't think dtor mean deg2radians because the source script that I want to translate use a "deg2rad" function during other calculation so , for me, dtor get another goal.

you can find here the math formula to calculate delta e 2000 :
https://en.wikipedia.org/wiki/Color_dif ... #CIEDE2000