ImageJ macro making a movie (stack) of zooming on selected rectangle (ROI)

zoom_movie_ImageJ_v2.ijm

//ImageJ macro making a movie (stack) of zooming on selected rectangle (ROI)
//Eugene Katrukha katpyxa at gmail.com
requires("1.48h");

//check if there is rectangular selection
if(selectionType() ==0)
{
	sTitle=getTitle();
	sMovieTitle=sTitle+"_zoom_movie";
	setBatchMode(true);
	
	//ROI parameters
	Roi.getBounds(nX, nY, nW, nH);
	//print(nX);
	//print(nY);
	//print(nW);
	//print(nH);
	
	//Dialog
	Dialog.create("Zoom-in parameters:");
	Dialog.addNumber("Number of frames for zoom-in:", 10);
	Dialog.addNumber("Add static number of frames in the end:", 10); 
	minMax=newArray("min","max");
	Dialog.addChoice("Zoom to min/max ROI size:", minMax); 
	sScaleChoice=newArray("same as ROI","Specified below");
	Dialog.addChoice("Final movie dimensions (px):", sScaleChoice); 
	Dialog.addNumber("Final movie width:", nW); 
	Dialog.addNumber("Final movie width:", nH); 
	Dialog.show();
	nFrames=Dialog.getNumber();
	nFramesLast=Dialog.getNumber();
	sChoice=Dialog.getChoice();
	sSizeChoice=Dialog.getChoice();
	nFinalW=Dialog.getNumber();
	nFinalH=Dialog.getNumber();
	
	//print(nFinalW);
	//print(nFinalH);
	
	imageH=getHeight();
	imageW=getWidth();
	rawID=getImageID();


	nCenterX=nX+0.5*nW;
	//print("CenterX");
	//print(nCenterX);
	nCenterY=nY+0.5*nH;
	//print("CenterY");
	//print(nCenterY);

	nScaleX=nW/imageW;
	nScaleY=nH/imageH;
	
		
	//adjust roi x/y ratio to image x/y ratio
	//depending on user choice
	if(startsWith(sChoice, "min"))
		nScaleFin=minOf(nScaleX,nScaleY);
	else
		nScaleFin=maxOf(nScaleX,nScaleY);
	
	nW=nScaleFin*imageW;
	nH=nScaleFin*imageH;
	//print("New nW");
	//print(nW);
	//print("New nH");
	//print(nH);
	nX=nCenterX-(nW*0.5);
	nY=nCenterY-(nH*0.5);
	//print(nX);
	//print(nY);
	
	//distance from (0,0) to left top corner of selsction
	length=sqrt(nX*nX+nY*nY);
	//print("length");
	//print(length);
	if(nX==0)
		angle=3.14/2;
	else
		angle=atan(nY/nX);
	//print("angle");
	//print(angle);	

	//final movie size
	if(startsWith(sSizeChoice,"same as"))
	{
		nFinalW=nW;
		nFinalH=nH;
	}
	else
	{
		nMovieScaleX=nW/nFinalW;
		nMovieScaleY=nH/nFinalH;
		nMovieFinalScale = minOf(nMovieScaleX,nMovieScaleY);
		nFinalW=nW/nMovieFinalScale;
		nFinalH=nH/nMovieFinalScale;
	}
	//print(nFinalW);
	//print(nFinalH);
	
	nScaleStep=(1-nScaleFin)/nFrames;
	bNotFirstIt=false;

	dCount =0;
	//for(nScale=1;nScale>=nScaleFin;nScale=nScale-nScaleStep)
	nScale=1;
	for(dCount =0;dCount<=nFrames;dCount++)
	{		
		selectImage(rawID);	
		//change viewport position/scale	
		dLen=length*dCount/nFrames;
		//print("dlen");
		//print(dLen);

		offsetX=dLen*cos(angle);
		offsetY=dLen*sin(angle);
		
		newW=imageW*nScale;
		newH=imageH*nScale;
		run("Specify...", "width="+toString(newW)+" height="+toString(newH)+" x="+toString(offsetX)+" y="+toString(offsetY));
		run("Duplicate...", "title="+sTitle+toString(nScale));
		unscaledID=getImageID();
		run("Scale...", "x=- y=- width="+toString(nFinalW)+" height="+toString(nFinalH)+" interpolation=Bicubic average create");
		scaledID=getImageID();
		selectImage(unscaledID);
		close();
		selectImage(scaledID);
		//not a first frame, let's add to existing movie stack
		if(bNotFirstIt)
		{
			sCurrTitle=sTitle+"x"+toString(nScale);
			rename(sCurrTitle);
			run("Concatenate...", "  title=["+sMovieTitle+"] image1=["+sMovieTitle+"] image2=["+sCurrTitle+"]");
		}
		//first frame, let's make accumulating stack out of it
		else
		{
			rename(sMovieTitle);
			sMovieID=getImageID();
			bNotFirstIt=true;
		}
		nScale=nScale-nScaleStep;
	}

	//adding static frames part
	nScale=nScaleFin;
	for(nAddFrames=1;nAddFrames<=nFramesLast;nAddFrames++)
	{
		selectImage(rawID);	
		offsetX=dLen*cos(angle);
		offsetY=dLen*sin(angle);
		newW=imageW*nScale;
		newH=imageH*nScale;
		run("Specify...", "width="+toString(newW)+" height="+toString(newH)+" x="+toString(offsetX)+" y="+toString(offsetY));
		run("Duplicate...", "title="+sTitle+toString(nScale));
		unscaledID=getImageID();
		run("Scale...", "x=- y=- width="+toString(nFinalW)+" height="+toString(nFinalH)+" interpolation=Bilinear average create");
		scaledID=getImageID();
		selectImage(unscaledID);
		close();
		selectImage(scaledID);
		sCurrTitle=sTitle+"x"+toString(nScale);
		rename(sCurrTitle);
		run("Concatenate...", "  title=["+sMovieTitle+"] image1=["+sMovieTitle+"] image2=["+sCurrTitle+"]");
			
	}
	setBatchMode(false);
}
//no rectangular ROI selection, error
else
{
	exit("Please choose rectangular selection (ROI) first.");
}

Hi, Thanks for the nice script. The problem I have is an excessive acceleration in the final frames of the movie. The last couple of frames the crop jumps into the image with zoom factor exceeding 3. The zooming curve seems very nonlinear and can't figure out how to change it in the code. Would you have any suggestions?

Thanks in advance,
Andrey

Sorry, I didn't receive your comment, just saw it now. But I see you've figured everything out! :)