anchor.diff:  ::%3 - thread number
   :savelog
   set /a "change=%~z1-%2"
  -if %change% equ 0 call:saverrorlog %1 1
   set /a "perc=%change%*100/%2" 2>nul
   set /a "fract=%change%*100%%%2*100/%2" 2>nul
   set /a "perc=%perc%*100+%fract%"
  
positive.code: 	set "ImageNum%%a=0"
  	set "TotalNum%%a=0"
  	set "TotalNumErr%%a=0"
  	set "TotalSize%%a=0"
  	set "STotalSize%%a=0"
  	set "ImageSize%%a=0"
  	set "SImageSize%%a=0"
  	set "change%%a=0"
  	set "perc%%a=0"
  	set "step%%a=10"
  )
  set "png="
  set "jpeg="
  
negative.code: endlocal & set /a "%~2=%}%"
  exit /b
  
  ::%1 - png | jpg | gif
  ::%2 - thread number
  ::%3 - input file
  