diff --git a/ui (gen4)/features/ui-single-image.js b/ui (gen4)/features/ui-single-image.js
index a762a8ed..11e68d60 100755
--- a/ui (gen4)/features/ui-single-image.js	
+++ b/ui (gen4)/features/ui-single-image.js	
@@ -85,57 +85,92 @@ var core = require('features/core')
 //
 //
 // XXX should this be an action???
-// XXX problems:
-// 		Q: what do we use for scale??
+// XXX .ribbons.correctImageProportionsForRotation(..) might be working 
+// 		incorrectly...
+// 		...when scaling a horizontal image, the thing starts jumping around....
 function updateImageProportions(){
+	var that = this
+	// XXX get this from config...
+	var threshold = this.config['single-image-proportions-threshold'] || 2
 	var viewer = this.ribbons.viewer
-	var image = viewer.find('.image')
 
-	var W = viewer.width()
-	var H = viewer.height()
-	var w = image.width()
-	var h = image.height()
+	// XXX
+	return
 
-	var R = W/H
-	var r = w/h
+	var img = this.ribbons.getImage()
+	var w = img.outerWidth()
+	var h = img.outerHeight()
 
-	var threshold = 3
-	var scale = Math.min(this.screenwidth, this.screenheight)
+	var c = Math.min(this.screenwidth, this.screenheight)
 
-	// XXX the idea is that:
-	// 		- up until a specific threshold:
-	// 			r is 1 
-	// 			we do not care about R
-	// 			XXX how do we define the threshold???
-	// 		- above that threshold:
-	// 			r tends to R relative to ???
-	// 		- when W == w && H == h
-	// 			r == R
-	// 		- beyond 
-	// 			r tends to actual image proportions
-	// 		- when (W == w || H == h) && r == actual image proportions
-	// 			we change nothing...
-	
-	// reset image proportions to square...
-	if(scale > threshold){
-		image.css({
-			width: '',
-			height: '',
+	// change proportions...
+	if(c < threshold){
+		var W = viewer.width()
+		var H = viewer.height()
+
+		// get dimensional scale....
+		var s = Math.min(W, H) / Math.min(w, h)
+
+		// XXX proportion s between s and 1 depending on c position 
+		// 		between threshold and 1
+		// 			s: const 				- changes with viewer size
+		// 			c: threshold -> 1
+		//
+		//		factor:
+		// 			f: 1/s -> 1
+		//
+		//var f = 
+		//s *= f
+
+		// get new dimension in image scale...
+		var n = Math.max(W, H) / s
+
+		if(n == Math.max(w, h)){
+			return
+		}
+
+		getAnimationFrame(function(){
+			that.ribbons.preventTransitions()
+
+			// horizontal viewer...
+			if(Math.min(W, H) == H){
+				// XXX
+				viewer.find('.ribbon .image')
+					.css({
+						width: n,
+						height: '',
+					})
+
+			// vertical viewer...
+			} else {
+				// XXX
+				viewer.find('.ribbon .image')
+					.css({
+						width: '',
+						height: n,
+					})
+			}
+		
+			that.centerImage()
+
+			that.ribbons.restoreTransitions(true)
 		})
 
-	// shift image container proportions between 1 and R, from threshold
-	// scale to 1...
-	} else if(scale >= 1){
-		// XXX
-	
-	// shift image container proportions between R and actual image 
-	// proportions...
-	} else if(W != w || H != h){
-		// XXX
+	// reset proportions to square...
+	} else if(w != h) {
+		getAnimationFrame(function(){
+			that.ribbons.preventTransitions()
 
-	// image container proportions are the same as image proportions...
-	} else {
-		// XXX
+			viewer.find('.ribbon .image')
+				.css({
+					width: '',
+					height: '',
+				})
+
+			that.centerImage()
+
+			that.ribbons.restoreTransitions(true)
+		})
 	}
 }
 
diff --git a/ui (gen4)/features/ui.js b/ui (gen4)/features/ui.js
index 8253bc58..2494ff61 100755
--- a/ui (gen4)/features/ui.js	
+++ b/ui (gen4)/features/ui.js	
@@ -538,19 +538,15 @@ module.ViewerActions = actions.Actions({
 		function(){ 
 			this.ribbons.origin()
 
-			var s = this.scale * (this.config['zoom-step'] || 1.2)
-
-			var W = this.ribbons.viewer.width()
-			var H = this.ribbons.viewer.height()
-			var w = this.ribbons.getVisibleImageSize('width', s)
-			var h = this.ribbons.getVisibleImageSize('height', s)
+			var d = (this.config['zoom-step'] || 1.2)
 
 			// limit scaling to screen dimensions...
-			if(this.config['max-zoom-to-screen'] && (W < w || H < h)){
-				this.fitImage(1)
+			if(this.config['max-zoom-to-screen'] 
+					&& (Math.min(this.screenwidth, this.screenheight) / d) < 1){
+				this.scale /= 1 / Math.min(this.screenwidth, this.screenheight)
 
 			} else {
-				this.scale = s
+				this.scale *= d
 			}
 		}],
 	zoomOut: ['Zoom/Zoom out',
@@ -560,7 +556,7 @@ module.ViewerActions = actions.Actions({
 			var max = this.config['max-screen-images']
 
 			if(max && max < (this.screenwidth * (this.config['zoom-step'] || 1.2))){
-				this.fitImage(max)
+				this.scale /= max / Math.min(this.screenwidth, this.screenheight)
 
 			} else {
 				this.scale /= (this.config['zoom-step'] || 1.2)