diff --git a/source/blender/blenkernel/BKE_image.h b/source/blender/blenkernel/BKE_image.h
index bf50648fea2..c8425d7853c 100644
--- a/source/blender/blenkernel/BKE_image.h
+++ b/source/blender/blenkernel/BKE_image.h
@@ -142,9 +142,6 @@ struct RenderPass *BKE_image_multilayer_index(struct RenderResult *rr, struct Im
 /* for multilayer images as well as for render-viewer */
 struct RenderResult *BKE_image_acquire_renderresult(struct Scene *scene, struct Image *ima);
 void BKE_image_release_renderresult(struct Scene *scene, struct Image *ima);
-
-/* frees all ibufs used by any image datablocks */
-void	BKE_image_free_image_ibufs(void);
 	
 /* goes over all textures that use images */
 void	BKE_image_free_all_textures(void);
diff --git a/source/blender/blenkernel/intern/colortools.c b/source/blender/blenkernel/intern/colortools.c
index 7bf147b4906..3c30332b18d 100644
--- a/source/blender/blenkernel/intern/colortools.c
+++ b/source/blender/blenkernel/intern/colortools.c
@@ -882,12 +882,12 @@ void curvemapping_table_RGBA(CurveMapping *cumap, float **array, int *size)
 
 DO_INLINE int get_bin_float(float f)
 {
-	int bin= (int)(f*511);
+	int bin= (int)(f*255);
 
 	/* note: clamp integer instead of float to avoid problems with NaN */
-	CLAMP(bin, 0, 511);
+	CLAMP(bin, 0, 255);
 	
-	//return (int) (((f + 0.25) / 1.5) * 512);
+	//return (int) (((f + 0.25) / 1.5) * 255);
 	
 	return bin;
 }
@@ -903,17 +903,20 @@ void histogram_update(Histogram *hist, ImBuf *ibuf)
 	
 	if (hist->ok == 1 ) return;
 	
+	if (hist->xmax == 0.f) hist->xmax = 1.f;
+	if (hist->ymax == 0.f) hist->ymax = 1.f;
+	
 	/* hmmmm */
 	if (!(ELEM(ibuf->channels, 3, 4))) return;
 	
 	hist->channels = 3;
 	
-	bin_r = MEM_callocN(512 * sizeof(unsigned int), "temp historgram bins");
-	bin_g = MEM_callocN(512 * sizeof(unsigned int), "temp historgram bins");
-	bin_b = MEM_callocN(512 * sizeof(unsigned int), "temp historgram bins");
+	bin_r = MEM_callocN(256 * sizeof(unsigned int), "temp historgram bins");
+	bin_g = MEM_callocN(256 * sizeof(unsigned int), "temp historgram bins");
+	bin_b = MEM_callocN(256 * sizeof(unsigned int), "temp historgram bins");
 	
 	if (ibuf->rect_float) {
-		hist->x_resolution = 512;
+		hist->x_resolution = 256;
 		
 		/* divide into bins */
 		rf = ibuf->rect_float;
@@ -942,7 +945,7 @@ void histogram_update(Histogram *hist, ImBuf *ibuf)
 	
 	/* convert to float */
 	n=0;
-	for (x=0; x<512; x++) {
+	for (x=0; x<256; x++) {
 		if (bin_r[x] > n)
 			n = bin_r[x];
 		if (bin_g[x] > n)
@@ -951,7 +954,7 @@ void histogram_update(Histogram *hist, ImBuf *ibuf)
 			n = bin_b[x];
 	}
 	div = 1.f/(double)n;
-	for (x=0; x<512; x++) {
+	for (x=0; x<256; x++) {
 		hist->data_r[x] = bin_r[x] * div;
 		hist->data_g[x] = bin_g[x] * div;
 		hist->data_b[x] = bin_b[x] * div;
diff --git a/source/blender/blenkernel/intern/image.c b/source/blender/blenkernel/intern/image.c
index ad7826ab9c4..cca3d561ed4 100644
--- a/source/blender/blenkernel/intern/image.c
+++ b/source/blender/blenkernel/intern/image.c
@@ -725,17 +725,6 @@ void BKE_image_print_memlist(void)
 	}
 }
 
-/* frees all ibufs used by any image datablocks */
-void BKE_image_free_image_ibufs(void)
-{
-	Image *ima;
-	
-	for(ima= G.main->image.first; ima; ima= ima->id.next) {
-		image_free_buffers(ima);
-	}
-	
-}
-
 void BKE_image_free_all_textures(void)
 {
 	Tex *tex;
diff --git a/source/blender/editors/interface/interface_draw.c b/source/blender/editors/interface/interface_draw.c
index 5363cf8937c..330209ef6f5 100644
--- a/source/blender/editors/interface/interface_draw.c
+++ b/source/blender/editors/interface/interface_draw.c
@@ -690,7 +690,7 @@ static void ui_draw_but_CHARTAB(uiBut *but)
 #endif
 
 
-void ui_draw_but_HISTOGRAM(uiBut *but, uiWidgetColors *wcol, rcti *recti)
+void ui_draw_but_HISTOGRAM(ARegion *ar, uiBut *but, uiWidgetColors *wcol, rcti *recti)
 {
 	Histogram *hist = (Histogram *)but->poin;
 	int res = hist->x_resolution;
@@ -699,6 +699,7 @@ void ui_draw_but_HISTOGRAM(uiBut *but, uiWidgetColors *wcol, rcti *recti)
 	int rgb;
 	float w, h;
 	float alpha;
+	GLint scissor[4];
 	
 	if (hist==NULL) { printf("hist is null \n"); return; }
 	
@@ -709,6 +710,7 @@ void ui_draw_but_HISTOGRAM(uiBut *but, uiWidgetColors *wcol, rcti *recti)
 	
 	w = rect.xmax - rect.xmin;
 	h = rect.ymax - rect.ymin;
+	h *= hist->ymax;
 	
 	glEnable(GL_BLEND);
 	glBlendFunc(GL_SRC_ALPHA,GL_ONE_MINUS_SRC_ALPHA);
@@ -724,6 +726,10 @@ void ui_draw_but_HISTOGRAM(uiBut *but, uiWidgetColors *wcol, rcti *recti)
 		fdrawline(rect.xmin+(i/4.f)*w, rect.ymin, rect.xmin+(i/4.f)*w, rect.ymax);
 	}
 	
+	/* need scissor test, histogram can draw outside of boundary */
+	glGetIntegerv(GL_VIEWPORT, scissor);
+	glScissor(ar->winrct.xmin + (rect.xmin-1), ar->winrct.ymin+(rect.ymin-1), (rect.xmax+1)-(rect.xmin-1), (rect.ymax+1)-(rect.ymin-1));
+		
 	for (rgb=0; rgb<3; rgb++) {
 		float *data;
 		
@@ -761,6 +767,9 @@ void ui_draw_but_HISTOGRAM(uiBut *but, uiWidgetColors *wcol, rcti *recti)
 		glDisable(GL_LINE_SMOOTH);
 	}
 	
+	/* restore scissortest */
+	glScissor(scissor[0], scissor[1], scissor[2], scissor[3]);
+	
 	glBlendFunc(GL_SRC_ALPHA,GL_ONE_MINUS_SRC_ALPHA);
 	glColor4f(0.f, 0.f, 0.f, 0.5f);
 	uiSetRoundBox(15);
diff --git a/source/blender/editors/interface/interface_handlers.c b/source/blender/editors/interface/interface_handlers.c
index 26215f78754..5a56877534d 100644
--- a/source/blender/editors/interface/interface_handlers.c
+++ b/source/blender/editors/interface/interface_handlers.c
@@ -2979,6 +2979,12 @@ static int ui_numedit_but_HSVCIRCLE(uiBut *but, uiHandleButtonData *data, int mx
 	ui_get_but_vectorf(but, rgb);
 	rgb_to_hsv(rgb[0], rgb[1], rgb[2], hsv, hsv+1, hsv+2);
 	
+	/* exception, when using color wheel in 'locked' value state:
+	 * allow choosing a hue for black values, by giving a tiny increment */
+	if (but->a2 == 1) { // lock
+		if (hsv[2] == 0.f) hsv[2] = 0.0001f;
+	}
+		
 	ui_hsvcircle_vals_from_pos(hsv, hsv+1, &rect, (float)mx, (float)my);
 	
 	hsv_to_rgb(hsv[0], hsv[1], hsv[2], rgb, rgb+1, rgb+2);
@@ -3412,6 +3418,81 @@ static int ui_do_but_CURVE(bContext *C, uiBlock *block, uiBut *but, uiHandleButt
 	return WM_UI_HANDLER_CONTINUE;
 }
 
+static int ui_numedit_but_HISTOGRAM(uiBut *but, uiHandleButtonData *data, int mx, int my)
+{
+	Histogram *hist = (Histogram *)but->poin;
+	rcti rect;
+	int changed= 1;
+	float dx, dy, yfac=1.f;
+	
+	rect.xmin= but->x1; rect.xmax= but->x2;
+	rect.ymin= but->y1; rect.ymax= but->y2;
+	
+	dx = mx - data->draglastx;
+	dy = my - data->draglasty;
+	
+	yfac = MIN2(powf(hist->ymax, 2.f), 1.f) * 0.5;
+	hist->ymax += dy * yfac;
+	
+	CLAMP(hist->ymax, 1.f, 100.f);
+	
+	data->draglastx= mx;
+	data->draglasty= my;
+	
+	return changed;
+}
+
+static int ui_do_but_HISTOGRAM(bContext *C, uiBlock *block, uiBut *but, uiHandleButtonData *data, wmEvent *event)
+{
+	int mx, my;
+	
+	mx= event->x;
+	my= event->y;
+	ui_window_to_block(data->region, block, &mx, &my);
+	
+	if(data->state == BUTTON_STATE_HIGHLIGHT) {
+		if(event->type==LEFTMOUSE && event->val==KM_PRESS) {
+			data->dragstartx= mx;
+			data->dragstarty= my;
+			data->draglastx= mx;
+			data->draglasty= my;
+			button_activate_state(C, but, BUTTON_STATE_NUM_EDITING);
+			
+			/* also do drag the first time */
+			if(ui_numedit_but_HISTOGRAM(but, data, mx, my))
+				ui_numedit_apply(C, block, but, data);
+			
+			return WM_UI_HANDLER_BREAK;
+		}
+		else if (event->type == ZEROKEY && event->val == KM_PRESS) {
+			Histogram *hist = (Histogram *)but->poin;
+			hist->ymax = 1.f;
+			
+			button_activate_state(C, but, BUTTON_STATE_EXIT);
+			return WM_UI_HANDLER_BREAK;
+		}
+	}
+	else if(data->state == BUTTON_STATE_NUM_EDITING) {
+		if(event->type == ESCKEY) {
+			data->cancel= 1;
+			data->escapecancel= 1;
+			button_activate_state(C, but, BUTTON_STATE_EXIT);
+		}
+		else if(event->type == MOUSEMOVE) {
+			if(mx!=data->draglastx || my!=data->draglasty) {
+				if(ui_numedit_but_HISTOGRAM(but, data, mx, my))
+					ui_numedit_apply(C, block, but, data);
+			}
+		}
+		else if(event->type==LEFTMOUSE && event->val!=KM_PRESS) {
+			button_activate_state(C, but, BUTTON_STATE_EXIT);
+		}
+		return WM_UI_HANDLER_BREAK;
+	}
+	
+	return WM_UI_HANDLER_CONTINUE;
+}
+
 #ifdef INTERNATIONAL
 static int ui_do_but_CHARTAB(bContext *C, uiBlock *block, uiBut *but, uiHandleButtonData *data, wmEvent *event)
 {
@@ -3926,7 +4007,7 @@ static int ui_do_button(bContext *C, uiBlock *block, uiBut *but, wmEvent *event)
 		}
 		/* reset to default */
 		else if(event->type == ZEROKEY && event->val == KM_PRESS) {
-			if (!(ELEM(but->type, HSVCIRCLE, HSVCUBE)))
+			if (!(ELEM3(but->type, HSVCIRCLE, HSVCUBE, HISTOGRAM)))
 				ui_set_but_default(C, but);
 		}
 		/* handle menu */
@@ -3996,8 +4077,9 @@ static int ui_do_button(bContext *C, uiBlock *block, uiBut *but, wmEvent *event)
 	case ROW:
 	case LISTROW:
 	case BUT_IMAGE:
-	case HISTOGRAM:
 		retval= ui_do_but_EXIT(C, but, data, event);
+	case HISTOGRAM:
+		retval= ui_do_but_HISTOGRAM(C, block, but, data, event);
 		break;
 	case TEX:
 	case IDPOIN:
diff --git a/source/blender/editors/interface/interface_intern.h b/source/blender/editors/interface/interface_intern.h
index 47892e45a02..1b4c56ed7d0 100644
--- a/source/blender/editors/interface/interface_intern.h
+++ b/source/blender/editors/interface/interface_intern.h
@@ -439,7 +439,7 @@ extern void gl_round_box_vertical_shade(int mode, float minx, float miny, float
 
 void ui_draw_gradient(rcti *rect, float *rgb, int type, float alpha);
 
-void ui_draw_but_HISTOGRAM(uiBut *but, struct uiWidgetColors *wcol, rcti *rect);
+void ui_draw_but_HISTOGRAM(ARegion *ar, uiBut *but, struct uiWidgetColors *wcol, rcti *rect);
 void ui_draw_but_COLORBAND(uiBut *but, struct uiWidgetColors *wcol, rcti *rect);
 void ui_draw_but_NORMAL(uiBut *but, struct uiWidgetColors *wcol, rcti *rect);
 void ui_draw_but_CURVE(ARegion *ar, uiBut *but, struct uiWidgetColors *wcol, rcti *rect);
diff --git a/source/blender/editors/interface/interface_widgets.c b/source/blender/editors/interface/interface_widgets.c
index aeea7d4a354..6f17a0d4e6a 100644
--- a/source/blender/editors/interface/interface_widgets.c
+++ b/source/blender/editors/interface/interface_widgets.c
@@ -2712,7 +2712,7 @@ void ui_draw_but(const bContext *C, ARegion *ar, uiStyle *style, uiBut *but, rct
 				break;
 			
 			case HISTOGRAM:
-				ui_draw_but_HISTOGRAM(but, &tui->wcol_regular, rect);
+				ui_draw_but_HISTOGRAM(ar, but, &tui->wcol_regular, rect);
 				break;
 				
 			case BUT_CURVE:
diff --git a/source/blender/editors/space_image/image_draw.c b/source/blender/editors/space_image/image_draw.c
index 69d0156d2fa..1b801060a23 100644
--- a/source/blender/editors/space_image/image_draw.c
+++ b/source/blender/editors/space_image/image_draw.c
@@ -701,11 +701,6 @@ void draw_image_main(SpaceImage *sima, ARegion *ar, Scene *scene)
 	/* render info */
 	if(ibuf && ima && show_render)
 		draw_render_info(ima, ar);
-
-	/* histogram */
-	if (ibuf) {
-		histogram_update(&sima->hist, ibuf);
-	}
 	
 	/* XXX integrate this code */
 #if 0
diff --git a/source/blender/editors/space_image/space_image.c b/source/blender/editors/space_image/space_image.c
index ad3407a7414..2a8158de79b 100644
--- a/source/blender/editors/space_image/space_image.c
+++ b/source/blender/editors/space_image/space_image.c
@@ -815,6 +815,13 @@ static void image_scope_area_init(wmWindowManager *wm, ARegion *ar)
 
 static void image_scope_area_draw(const bContext *C, ARegion *ar)
 {
+	SpaceImage *sima= CTX_wm_space_image(C);
+	void *lock;
+	ImBuf *ibuf= ED_space_image_acquire_buffer(sima, &lock);
+	
+	histogram_update(&sima->hist, ibuf);
+	ED_space_image_release_buffer(sima, lock);
+	
 	ED_region_panels(C, ar, 1, NULL, -1);
 }
 
@@ -822,6 +829,22 @@ static void image_scope_area_listener(ARegion *ar, wmNotifier *wmn)
 {
 	/* context changes */
 	switch(wmn->category) {
+		case NC_SCENE:
+			switch(wmn->data) {
+				case ND_MODE:
+				case ND_RENDER_RESULT:
+				case ND_COMPO_RESULT:
+					ED_region_tag_redraw(ar);
+					break;
+			}
+			break;
+		case NC_IMAGE:
+			ED_region_tag_redraw(ar);
+			break;
+		case NC_NODE:
+			ED_region_tag_redraw(ar);
+			break;
+			
 	}
 }
 
diff --git a/source/blender/makesdna/DNA_color_types.h b/source/blender/makesdna/DNA_color_types.h
index 3094ab69ca2..f971a0a0480 100644
--- a/source/blender/makesdna/DNA_color_types.h
+++ b/source/blender/makesdna/DNA_color_types.h
@@ -83,12 +83,12 @@ typedef struct CurveMapping {
 typedef struct Histogram {
 	int channels;
 	int x_resolution;
-	float data_r[512];
-	float data_g[512];
-	float data_b[512];
-	float min, max;
+	float data_r[256];
+	float data_g[256];
+	float data_b[256];
+	float xmax, ymax;
 	int ok;
-	int pad;
+	int flag;
 } Histogram;
 
 #endif
diff --git a/source/blender/makesrna/intern/rna_scene.c b/source/blender/makesrna/intern/rna_scene.c
index 3f79a06566d..709165ecf83 100644
--- a/source/blender/makesrna/intern/rna_scene.c
+++ b/source/blender/makesrna/intern/rna_scene.c
@@ -524,8 +524,22 @@ static int rna_SceneRenderData_engine_get(PointerRNA *ptr)
 
 static void rna_SceneRenderData_color_management_update(Main *bmain, Scene *unused, PointerRNA *ptr)
 {
-	/* reset all generated image block buffers to prevent out-of-date conversions */
-	BKE_image_free_image_ibufs();
+	/* reset image nodes */
+	Scene *scene= (Scene*)ptr->id.data;
+	bNodeTree *ntree=scene->nodetree;
+	bNode *node;
+	
+	if(ntree && scene->use_nodes) {
+		for (node=ntree->nodes.first; node; node=node->next) {
+			if (ELEM(node->type, CMP_NODE_VIEWER, CMP_NODE_IMAGE)) {
+				ED_node_changed_update(&scene->id, node);
+				WM_main_add_notifier(NC_NODE|NA_EDITED, node);
+				
+				if (node->type == CMP_NODE_IMAGE)
+					BKE_image_signal((Image *)node->id, NULL, IMA_SIGNAL_RELOAD);
+			}
+		}
+	}
 }
 
 static void rna_SceneRenderLayer_name_set(PointerRNA *ptr, const char *value)