import java.lang.Math;

getROI() {
	a = new int[4][1];
	mmc.getROI(a[0],a[1],a[2],a[3]);
	int[] roiRect = {a[0][0],a[1][0],a[2][0],a[3][0]};
	return roiRect;
}

setROI(roiRect) {
	mmc.setROI(roiRect[0],roiRect[1],roiRect[2],roiRect[3]);
}

// Set relative offset between cameras:
int [] offset2 = {100,100};

// Get current pixel size and ROI for first camera:
mmc.setCameraDevice("Camera-1");
double pixelSize1 = mmc.getPixelSizeUm();
roi1 = getROI();

// Get current pixel size for second camera:
mmc.setCameraDevice("Camera-2");
double pixelSize2 = mmc.getPixelSizeUm();

// Compute ROI for second camera:

ratio = pixelSize2 / pixelSize1;
int [] roi2 = { offset2[0],
					 offset2[1],
					 Math.round(roi1[2] * ratio),
					 Math.round(roi1[3] * ratio) };

// Set ROI for second camera:
setROI(roi2);