Ultra HDR Script

This script provides a complete HDR / Exposure Bracketing environment for use with CHDK.

It combines various aspects of many existing HDR scripts and will work on any CHDK equipped camera.  It has no embedded keyboard presses or fixed parameter set variables that would make it specific to a particular camera.  However, it is designed to run best with CHDK 1.2.0 or newer - see the bottom of this page for instructions on converting for CHDK 1.1.0.

Script Description

The script allows the user to vary one of the three camera exposure parameters (Tv, Av, Sv) while holding the other two fixed.  This results in several shots at different exposure settings,  suitable for creating HDR images in your computer.

Note :  as many Canon P&S cameras do not have adjustable aperture. 

forum link > http://chdk.setepontos.com/index.php?topic=9557

Script Operation

1. HDR mode - choose better shutter (Tv),  Iris (Av),  or ISO (Sv).
2. Exposure Steps - this determines the number of photos taken at different exposures.
3. 1/2 f-stops per step - the exposure adjustment made between shots
4. Exposure offset -  allow you to shift the exposure of all shots up or down by a fixed amount.
5. Raw - override current RAW setting (restored on script exit)

Lua Script

UltraHDR.lua : for CHDK v1.2.0 or greater (see note below)

--[[
 @title Ultra HDR

 @param m HDR Exposure Mode
    @default m 0
    @values m Shutter Iris ISO
 @param n Exposure Steps
    @default n 3
    @range n 2 8
 @param a 1/2 f-stops per Step
    @default a 2
    @range a 1 10
 @param e Exposure Offset (stops)
    @default e 0
    @range e -4 4
 @param r Raw & DNG
    @default r 
    @values r Ignore Disable Enable
 --]] 
 
-- release AF lock & restore RAW state on exit
 function restore()
    if ( r>0 ) then set_raw(rawmode) end
    set_aflock(0)
 end
 
--setup
 set_console_layout(1, 0, 45, 12) 
 rawmode=get_raw()
 if( r>0 ) then set_raw(r-1) end
 print("Ultra HDR started...")

-- switch to shooting mode
 if ( get_mode() == false ) then
    sleep(1000)
    set_record(1)
    while ( get_mode() == false) do
       sleep(100)
    end
 end
 sleep(100)

-- focus and take exposure
 press("shoot_half") 
 repeat
    sleep(50)
 until get_shooting() == true 
    release("shoot_half") 
 repeat
    sleep(50)
 until get_shooting() == false
   set_aflock(1)
   av=get_av96() 
   sv=get_sv96() 
   tv=get_tv96() 

-- configure the shots
   print( "start","tv=", tv, "av=", av, "sv=", sv )
   s=a*48
   tv_inc=0
   av_inc=0
   sv_inc=0
   if(m==0) then
      tv=tv-n*s/2+e*96
      tv_inc=s
   elseif ( m==1 ) then 
      av=av-n*s/2+e*96
      av_inc=s
   elseif ( m == 2 ) then
      sv=sv-n*s/2+e*96
      sv_inc=s
   end

--shoot
 for i=1, n, 1 do
   print(i, "tv=", tv, "av=", av, "sv=", sv )
   set_tv96_direct(tv)
   set_av96_direct(av)
   set_sv96(sv)
   shoot()   
   tv = tv + tv_inc
   av = av + av_inc
   sv = sv + sv_inc
 end

restore()
print("...done")

Script Notes

For CHDK versions 1.1 or earlier, change the header of the script to the following :

--[[
 @title Ultra HDR

 @param m Mode [Tv=0,Ev=1,Sv=2]
    @default m 0
    @range m 0 2
 @param n Exposure Steps
    @default n 3
    @range n 2 8
 @param a 1/2 f-stops per Step
    @default a 2
    @range a 1 10
 @param e Exposure Offset [stops]
    @default e 0
    @range e -4 4
 @param r Raw/DNG [0=auto,1=off,2=on]
    @default r 
    @range r 0 2
 --]]