function isPreviousOK() {
	if(curImage > 1) {
		return true
	} else {
		return false
	}
}

function isNextOK() {
	if(curImage < numImages) {
		return true
	} else {
		return false
	}
}

function changeImage(direction) {
	// Change the source of the image
	if(direction < 0) {
		if(isPreviousOK()) {
			curImage--
		}
	} else if(direction > 0) {
		if(isNextOK()) {
			curImage++
		}
	}
	var oldImageSrc = document["main"].src
	i = oldImageSrc.lastIndexOf("/image")
	var newImageSrc = oldImageSrc.substring(0, i + 6) + curImage + ".jpg"
	document["main"].src = newImageSrc
	
	updatePrevNext()
}

function setImage(imgNumber) {
	var oldImageSrc = document["main"].src
	i = oldImageSrc.lastIndexOf("/image")
	var newImageSrc = oldImageSrc.substring(0, i + 6) + imgNumber + ".jpg"
	document["main"].src = newImageSrc
	curImage = imgNumber
	
	updatePrevNext()
}

function updatePrevNext() {
	if(isPreviousOK()) {
		document["PrevNext1"]["Previous"].disabled = false
		document["PrevNext2"]["Previous"].disabled = false
	} else {
		document["PrevNext1"]["Previous"].disabled = true
		document["PrevNext2"]["Previous"].disabled = true
	}
	
	if(isNextOK()) {
		document["PrevNext1"]["Next"].disabled = false
		document["PrevNext2"]["Next"].disabled = false
	} else {
		document["PrevNext1"]["Next"].disabled = true
		document["PrevNext2"]["Next"].disabled = true
	}
	
	for(i=1; i<=numImages; i++) {
		var tmp = "image" + i
		if(curImage == i) {
			document[tmp].style.border = "3px solid #0000ff"
		} else {
			document[tmp].style.border = "0px"
		}
	}
}