Compare Overlaid 2D Images

test(5,101); setup()

wave1

wsave

Test(f,Npts)

setup()

#pragma rtGlobals=3		// Use modern global access method and strict wave access.

Function Test(f, Npts)  // make two test images for comparison
	variable f , Npts    // spatial frequency for test images; number of points
	make/O/N=(Npts, Npts) wave0
	setscale/I x, -0.5, 0.5, "" wave0
	setscale/I y, -0.5, 0.5, "" wave0
	wave0  = (cos(x*2*pi*f)*cos(y*2*pi*f))^2
	duplicate/O wave0, wave1
	MatrixOp  /O /S wave1 = 0.75*RotateCols(wave1, 3)  // alter wave1 from wave0
	duplicate/O wave1, wsave   // save a copy
end

Function setup()  // Graph the bottom (wave0) and top (wave1) images; add slider and its hook sizing function
	WAVE wave0, wave1, wsave
	variable/G Nmax = DimSize(wave0, 0) - 1 // x-dimension points for Slider max value
	variable Vmax0 = waveMax(wave0)
	variable Vmin0  = waveMin( wave0)
	variable Vmax1 = waveMax(wave1)
	variable Vmin1  = waveMin( wave1)
	variable Vmax   = max(Vmax0, Vmax1) // for common color scale ranges
	variable Vmin    = min(Vmin0, Vmin1)
	variable/G pG	//	global pixel value for slider

	DoWindow/F Graph0   // Bring graph to front
	if (V_Flag == 0)          // if not found, make new Graph0 for overlaid images with slider for transparent boundary
		PauseUpdate; Silent 1.
		Display/N=Graph0 /W=(413.25,44.75,769.5,427.25)
		AppendImage/T wave0
		AppendImage/T wave1
		ModifyGraph margin(left)=14,margin(bottom)=14,margin(top)=14,margin(right)=14,height={Plan,1,left,top}
		ModifyGraph mirror=2, nticks=3, minor=1,fSize=8, standoff=0, tkLblRot(left)=90, btLen=3,  tlOffset=-2
		SetAxis/A/R left
		ControlBar/B 35
		Slider slider0,pos={11,482},size={455,16},proc=SliderProc
		Slider slider0,limits={0,Nmax,1},variable= pG,side= 2,vert= 0,ticks= 0
		SetWindow kwTopWin,hook(MyHook)=MyWindowHook
		DoUpdate
	endif
	GetWindow  Graph0, psizeDC // gets V_left, V_right, V_top, V_bottom
	ModifyImage wave0 ctab= {Vmin,Vmax,Terrain,0}
	ModifyImage wave1 ctab= {Vmin,Vmax,Terrain,0} // common limits
	Slider slider0 limits = { 0, Nmax, 1}
	Slider slider0 pos   = { 11,  V_bottom+25}
	Slider slider0 size   = { V_right-V_left+16, 20 }
End

Function compare(n)
	variable n
	
	WAVE wave0, wave1, wsave
	wave1 = wsave  // reload full original
	if (n==0)
		return 0
	endif
	wave1[0,n][] = NaN // make left side of top image transparent
End

Function SliderProc(ctrlName,sliderValue,event) : SliderControl
	String ctrlName
	Variable sliderValue
	Variable event	// bit field: bit 0: value set, 1: mouse down, 2: mouse up, 3: mouse moved

	if(event %& 0x1)	// bit 0, value set
		compare(sliderValue)
	endif

	return 0
End

Function MyWindowHook(s)	//	if window resized, adjust slider to match
	STRUCT WMWinHookStruct &s
	Variable hookResult = 0
	wave wave0
	switch(s.eventCode)
		case 6: // graph resize
			GetWindow  Graph0, psizeDC
			Slider slider0 pos   = { 11,  V_bottom+25}
			Slider slider0 size  = { V_right-V_Left+16, 20 }
			break
		case 8: // graph (wave size) modified
			Slider slider0 limits = { 0,(DimSize(wave0, 0) - 1), 1}
			break
	endswitch
	return hookResult // 0 if nothing done, else 1
End