Finished some work from the weekend to keep local tree clean..

* Added a generic 'histogram' ui control, currently available in new image editor 
'scopes' region (shortcut P). Shows the histogram of the currently viewed image.

It's a baby step in unifying the functionality and code from the sequence editor, 
so eventually we can migrate the sequence preview to the image editor too, 
like compositor.

Still a couple of rough edges to tweak, regarding when it updates. Also would 
be very nice to have this region as a partially transparent overlapping region...

release/scripts/ui/space_image.py

@@ -35,6 +35,7 @@ class IMAGE_MT_view(bpy.types.Menu):
         show_uvedit = sima.show_uvedit
 
         layout.operator("image.properties", icon='MENU_PANEL')
+        layout.operator("image.scopes", icon='MENU_PANEL')
 
         layout.separator()
 
@@ -386,6 +387,21 @@ class IMAGE_PT_game_properties(bpy.types.Panel):
         col.separator()
         col.prop(ima, "mapping", expand=True)
 
+class IMAGE_PT_view_histogram(bpy.types.Panel):
+    bl_space_type = 'IMAGE_EDITOR'
+    bl_region_type = 'PREVIEW'
+    bl_label = "Histogram"
+    
+    def poll(self, context):
+        sima = context.space_data
+        return (sima and sima.image)
+    
+    def draw(self, context):
+        layout = self.layout
+
+        sima = context.space_data
+                        
+        layout.template_histogram(sima, "histogram")
 
 class IMAGE_PT_view_properties(bpy.types.Panel):
     bl_space_type = 'IMAGE_EDITOR'
@@ -417,6 +433,7 @@ class IMAGE_PT_view_properties(bpy.types.Panel):
             col.prop(sima, "draw_repeated", text="Repeat")
             if show_uvedit:
                 col.prop(uvedit, "normalized_coordinates", text="Normalized")
+
         elif show_uvedit:
             col.label(text="Coordinates:")
             col.prop(uvedit, "normalized_coordinates", text="Normalized")
@@ -562,3 +579,4 @@ bpy.types.register(IMAGE_PT_paint_stroke)
 bpy.types.register(IMAGE_PT_paint_curve)
 bpy.types.register(IMAGE_PT_game_properties)
 bpy.types.register(IMAGE_PT_view_properties)
+bpy.types.register(IMAGE_PT_view_histogram)

release/scripts/ui/space_userpref.py

@@ -735,6 +735,7 @@ class USERPREF_PT_theme(bpy.types.Panel):
 
             col = split.column()
             col.prop(image, "back")
+            col.prop(image, "scope_back")
             col.prop(image, "button")
 
             col = split.column()

source/blender/blenkernel/BKE_colortools.h

@@ -31,6 +31,7 @@
 
 struct CurveMapping;
 struct CurveMap;
+struct Histogram;
 struct ImBuf;
 struct rctf;
 
@@ -70,6 +71,7 @@ void				curvemapping_initialize(struct CurveMapping *cumap);
 void				curvemapping_table_RGBA(struct CurveMapping *cumap, float **array, int *size);
 void				colorcorrection_do_ibuf(struct ImBuf *ibuf, const char *profile);
 
+void				histogram_update(struct Histogram *hist, struct ImBuf *ibuf);
 
 #endif
 

source/blender/blenkernel/intern/colortools.c

@@ -878,3 +878,85 @@ void curvemapping_table_RGBA(CurveMapping *cumap, float **array, int *size)
 	}
 }
 
+/* ***************** Histogram **************** */
+
+static inline int get_bin_float(float f)
+{
+	CLAMP(f, 0.0, 1.0);
+	
+	//return (int) (((f + 0.25) / 1.5) * 512);
+	
+	return (int)(f * 511);
+}
+
+
+void histogram_update(Histogram *hist, ImBuf *ibuf)
+{
+	int x, y, n;
+	double div;
+	float *rf;
+	unsigned char *rc;
+	unsigned int *bin_r, *bin_g, *bin_b;
+	
+	if (hist->ok == 1 ) return;
+	
+	/* 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");
+	
+	if (ibuf->rect_float) {
+		hist->x_resolution = 512;
+		
+		/* divide into bins */
+		rf = ibuf->rect_float;
+		for (y = 0; y < ibuf->y; y++) {
+			for (x = 0; x < ibuf->x; x++) {
+				bin_r[ get_bin_float(rf[0]) ] += 1;
+				bin_g[ get_bin_float(rf[1]) ] += 1;
+				bin_b[ get_bin_float(rf[2]) ] += 1;
+				rf+= ibuf->channels;
+			}
+		}
+	}
+	else if (ibuf->rect) {
+		hist->x_resolution = 256;
+		
+		rc = (unsigned char *)ibuf->rect;
+		for (y = 0; y < ibuf->y; y++) {
+			for (x = 0; x < ibuf->x; x++) {
+				bin_r[ rc[0] ] += 1;
+				bin_g[ rc[1] ] += 1;
+				bin_b[ rc[2] ] += 1;
+				rc += ibuf->channels;
+			}
+		}
+	}
+	
+	/* convert to float */
+	n=0;
+	for (x=0; x<512; x++) {
+		if (bin_r[x] > n)
+			n = bin_r[x];
+		if (bin_g[x] > n)
+			n = bin_g[x];
+		if (bin_b[x] > n)
+			n = bin_b[x];
+	}
+	div = 1.f/(double)n;
+	for (x=0; x<512; 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;
+	}
+	
+	MEM_freeN(bin_r);
+	MEM_freeN(bin_g);
+	MEM_freeN(bin_b);
+	
+	hist->ok=1;
+}

source/blender/editors/include/UI_interface.h

@@ -216,6 +216,7 @@ typedef struct uiLayout uiLayout;
 #define LISTROW		(44<<9)
 #define HOTKEYEVT	(45<<9)
 #define BUT_IMAGE	(46<<9)
+#define HISTOGRAM	(47<<9)
 
 #define BUTTYPE		(63<<9)
 
@@ -654,6 +655,7 @@ uiLayout *uiTemplateModifier(uiLayout *layout, struct PointerRNA *ptr);
 uiLayout *uiTemplateConstraint(uiLayout *layout, struct PointerRNA *ptr);
 void uiTemplatePreview(uiLayout *layout, struct ID *id, struct ID *parent, struct MTex *slot);
 void uiTemplateColorRamp(uiLayout *layout, struct PointerRNA *ptr, char *propname, int expand);
+void uiTemplateHistogram(uiLayout *layout, struct PointerRNA *ptr, char *propname, int expand);
 void uiTemplateCurveMapping(uiLayout *layout, struct PointerRNA *ptr, char *propname, int type, int levels, int brush);
 void uiTemplateColorWheel(uiLayout *layout, struct PointerRNA *ptr, char *propname, int value_slider);
 void uiTemplateTriColorSet(uiLayout *layout, struct PointerRNA *ptr, char *propname);

source/blender/editors/include/UI_resources.h

@@ -207,6 +207,8 @@ enum {
 	
 	TH_DOPESHEET_CHANNELOB,
 	TH_DOPESHEET_CHANNELSUBOB,
+	
+	TH_PREVIEW_BACK,
 };
 /* XXX WARNING: previous is saved in file, so do not change order! */
 

source/blender/editors/interface/interface_draw.c

@@ -691,6 +691,87 @@ static void ui_draw_but_CHARTAB(uiBut *but)
 #endif // INTERNATIONAL
 #endif
 
+
+void ui_draw_but_HISTOGRAM(uiBut *but, uiWidgetColors *wcol, rcti *recti)
+{
+	Histogram *hist = (Histogram *)but->poin;
+	int res = hist->x_resolution;
+	rctf rect;
+	int i;
+	int rgb;
+	float w, h;
+	float alpha;
+	
+	if (hist==NULL) { printf("hist is null \n"); return; }
+	
+	rect.xmin = (float)recti->xmin;
+	rect.xmax = (float)recti->xmax;
+	rect.ymin = (float)recti->ymin;
+	rect.ymax = (float)recti->ymax;
+	
+	w = rect.xmax - rect.xmin;
+	h = rect.ymax - rect.ymin;
+	
+	glEnable(GL_BLEND);
+	glBlendFunc(GL_SRC_ALPHA,GL_ONE_MINUS_SRC_ALPHA);
+	
+	glColor4f(0.f, 0.f, 0.f, 0.3f);
+	uiSetRoundBox(15);
+	gl_round_box(GL_POLYGON, rect.xmin-1, rect.ymin-1, rect.xmax+1, rect.ymax+1, 3.0f);
+	
+	glColor4f(1.f, 1.f, 1.f, 0.08f);
+	/* draw grid lines here */
+	for (i=1; i<4; i++) {
+		fdrawline(rect.xmin, rect.ymin+(i/4.f)*h, rect.xmax, rect.ymin+(i/4.f)*h);
+		fdrawline(rect.xmin+(i/4.f)*w, rect.ymin, rect.xmin+(i/4.f)*w, rect.ymax);
+	}
+	
+	for (rgb=0; rgb<3; rgb++) {
+		float *data;
+		
+		if (rgb==0)			data = hist->data_r;
+		else if (rgb==1)	data = hist->data_g;
+		else if (rgb==2)	data = hist->data_b;
+		
+		glBlendFunc(GL_SRC_ALPHA, GL_ONE);
+		alpha = 0.75;
+		if (rgb==0)			glColor4f(1.f, 0.f, 0.f, alpha);
+		else if (rgb==1)	glColor4f(0.f, 1.f, 0.f, alpha);
+		else if (rgb==2)	glColor4f(0.f, 0.f, 1.f, alpha);
+		
+		glShadeModel(GL_FLAT);
+		glBegin(GL_QUAD_STRIP);
+		glVertex2f(rect.xmin, rect.ymin);
+		glVertex2f(rect.xmin, rect.ymin + (data[0]*h));
+		for (i=1; i < res; i++) {
+			float x = rect.xmin + i * (w/(float)res);
+			glVertex2f(x, rect.ymin + (data[i]*h));
+			glVertex2f(x, rect.ymin);
+		}
+		glEnd();
+		
+		glColor4f(0.f, 0.f, 0.f, 0.25f);
+		
+		glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
+		glEnable(GL_LINE_SMOOTH);
+		glBegin(GL_LINE_STRIP);
+		for (i=0; i < res; i++) {
+			float x = rect.xmin + i * (w/(float)res);
+			glVertex2f(x, rect.ymin + (data[i]*h));
+		}
+		glEnd();
+		glDisable(GL_LINE_SMOOTH);
+	}
+	
+	glBlendFunc(GL_SRC_ALPHA,GL_ONE_MINUS_SRC_ALPHA);
+	glColor4f(0.f, 0.f, 0.f, 0.5f);
+	uiSetRoundBox(15);
+	gl_round_box(GL_LINE_LOOP, rect.xmin-1, rect.ymin-1, rect.xmax+1, rect.ymax+1, 3.0f);
+	
+	glDisable(GL_BLEND);
+}
+
+
 void ui_draw_but_COLORBAND(uiBut *but, uiWidgetColors *wcol, rcti *rect)
 {
 	ColorBand *coba;

source/blender/editors/interface/interface_handlers.c

@@ -751,7 +751,13 @@ static void ui_apply_but_LINK(bContext *C, uiBut *but, uiHandleButtonData *data)
 static void ui_apply_but_IMAGE(bContext *C, uiBut *but, uiHandleButtonData *data)
 {
 	ui_apply_but_func(C, but);
+	data->retval= but->retval;
+	data->applied= 1;
+}
 
+static void ui_apply_but_HISTOGRAM(bContext *C, uiBut *but, uiHandleButtonData *data)
+{
+	ui_apply_but_func(C, but);
 	data->retval= but->retval;
 	data->applied= 1;
 }
@@ -878,6 +884,9 @@ static void ui_apply_button(bContext *C, uiBlock *block, uiBut *but, uiHandleBut
 		case BUT_IMAGE:	
 			ui_apply_but_IMAGE(C, but, data);
 			break;
+		case HISTOGRAM:	
+			ui_apply_but_HISTOGRAM(C, but, data);
+			break;
 		default:
 			break;
 	}
@@ -3782,6 +3791,7 @@ 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);
 		break;
 	case TEX:

source/blender/editors/interface/interface_intern.h

@@ -426,12 +426,12 @@ extern void gl_round_box(int mode, float minx, float miny, float maxx, float max
 extern void gl_round_box_shade(int mode, float minx, float miny, float maxx, float maxy, float rad, float shadetop, float shadedown);
 extern void gl_round_box_vertical_shade(int mode, float minx, float miny, float maxx, float maxy, float rad, float shadeLeft, float shadeRight);
 
+void ui_draw_but_HISTOGRAM(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);
 void ui_draw_but_IMAGE(ARegion *ar, uiBut *but, struct uiWidgetColors *wcol, rcti *rect);
 
-
 /* interface_handlers.c */
 extern void ui_button_activate_do(struct bContext *C, struct ARegion *ar, uiBut *but);
 extern void ui_button_active_cancel(const struct bContext *C, uiBut *but);

source/blender/editors/interface/interface_panel.c

@@ -108,6 +108,8 @@ static int panel_aligned(ScrArea *sa, ARegion *ar)
 		return BUT_VERTICAL;
 	else if(sa->spacetype==SPACE_FILE && ar->regiontype == RGN_TYPE_CHANNELS)
 		return BUT_VERTICAL;
+	else if(sa->spacetype==SPACE_IMAGE && ar->regiontype == RGN_TYPE_PREVIEW)
+		return BUT_VERTICAL; 
 	else if(ELEM3(ar->regiontype, RGN_TYPE_UI, RGN_TYPE_TOOLS, RGN_TYPE_TOOL_PROPS))
 		return BUT_VERTICAL;
 	
@@ -130,6 +132,8 @@ static int panels_re_align(ScrArea *sa, ARegion *ar, Panel **r_pa)
 	}
 	else if(ar->regiontype==RGN_TYPE_UI)
 		return 1;
+	else if(sa->spacetype==SPACE_IMAGE && ar->regiontype == RGN_TYPE_PREVIEW)
+		return 1;
 	else if(sa->spacetype==SPACE_FILE && ar->regiontype == RGN_TYPE_CHANNELS)
 		return 1;
 

source/blender/editors/interface/interface_templates.c

@@ -28,6 +28,7 @@
 
 #include "MEM_guardedalloc.h"
 
+#include "DNA_color_types.h"
 #include "DNA_scene_types.h"
 #include "DNA_screen_types.h"
 
@@ -1527,9 +1528,45 @@ void uiTemplateColorRamp(uiLayout *layout, PointerRNA *ptr, char *propname, int
 	MEM_freeN(cb);
 }
 
+/********************* Histogram Template ************************/
+
+void uiTemplateHistogram(uiLayout *layout, PointerRNA *ptr, char *propname, int expand)
+{
+	PropertyRNA *prop= RNA_struct_find_property(ptr, propname);
+	PointerRNA cptr;
+	RNAUpdateCb *cb;
+	uiBlock *block;
+	uiBut *bt;
+	Histogram *hist;
+	rctf rect;
+	
+	if(!prop || RNA_property_type(prop) != PROP_POINTER)
+		return;
+	
+	cptr= RNA_property_pointer_get(ptr, prop);
+	if(!cptr.data || !RNA_struct_is_a(cptr.type, &RNA_Histogram))
+		return;
+	
+	cb= MEM_callocN(sizeof(RNAUpdateCb), "RNAUpdateCb");
+	cb->ptr= *ptr;
+	cb->prop= prop;
+	
+	rect.xmin= 0; rect.xmax= 200;
+	rect.ymin= 0; rect.ymax= 190;
+	
+	block= uiLayoutAbsoluteBlock(layout);
+	//colorband_buttons_layout(layout, block, cptr.data, &rect, !expand, cb);
+	
+	hist = (Histogram *)cptr.data;
+	
+	bt= uiDefBut(block, HISTOGRAM, 0, "",		rect.xmin, rect.ymin, rect.xmax-rect.xmin, 100.0f, hist, 0, 0, 0, 0, "");
+	uiButSetNFunc(bt, rna_update_cb, MEM_dupallocN(cb), NULL);
+	
+	MEM_freeN(cb);
+}
+
 /********************* CurveMapping Template ************************/
 
-#include "DNA_color_types.h"
 #include "BKE_colortools.h"
 
 static void curvemap_buttons_zoom_in(bContext *C, void *cumap_v, void *unused)

source/blender/editors/interface/interface_widgets.c

@@ -1796,6 +1796,7 @@ static void ui_draw_but_HSV_v(uiBut *but, rcti *rect)
 	
 }
 
+
 /* ************ separator, for menus etc ***************** */
 static void ui_draw_separator(uiBut *but, rcti *rect,  uiWidgetColors *wcol)
 {
@@ -2663,6 +2664,10 @@ void ui_draw_but(const bContext *C, ARegion *ar, uiStyle *style, uiBut *but, rct
 			case BUT_IMAGE:
 				ui_draw_but_IMAGE(ar, but, &tui->wcol_regular, rect);
 				break;
+			
+			case HISTOGRAM:
+				ui_draw_but_HISTOGRAM(but, &tui->wcol_regular, rect);
+				break;
 				
 			case BUT_CURVE:
 				ui_draw_but_CURVE(ar, but, &tui->wcol_regular, rect);

source/blender/editors/interface/resources.c

@@ -368,7 +368,10 @@ char *UI_ThemeGetColorPtr(bTheme *btheme, int spacetype, int colorid)
 			case TH_DOPESHEET_CHANNELSUBOB:
 				cp= ts->ds_subchannel;
 				break;	
-				
+					
+			case TH_PREVIEW_BACK:
+				cp= ts->preview_back;
+				break;	
 			}
 		}
 	}
@@ -569,6 +572,7 @@ void ui_theme_init_userdef(void)
 	SETCOL(btheme->tima.face,   255, 255, 255, 10);
 	SETCOL(btheme->tima.face_select, 255, 133, 0, 60);
 	SETCOL(btheme->tima.editmesh_active, 255, 255, 255, 128);
+	SETCOLF(btheme->tima.preview_back, 	0.45, 0.45, 0.45, 1.0);
 
 	/* space imageselect */
 	btheme->timasel= btheme->tv3d;

source/blender/editors/screen/area.c

@@ -1318,7 +1318,11 @@ void ED_region_panels(const bContext *C, ARegion *ar, int vertical, char *contex
 	}
 
 	/* clear */
-	UI_GetThemeColor3fv(TH_BACK, col);
+	if (ar->type->regionid == RGN_TYPE_PREVIEW)
+		UI_GetThemeColor3fv(TH_PREVIEW_BACK, col);
+	else
+		UI_GetThemeColor3fv(TH_BACK, col);
+	
 	glClearColor(col[0], col[1], col[2], 0.0);
 	glClear(GL_COLOR_BUFFER_BIT);
 

source/blender/editors/space_image/image_buttons.c

@@ -1036,5 +1036,26 @@ void IMAGE_OT_properties(wmOperatorType *ot)
 	ot->flag= 0;
 }
 
+static int image_scopes(bContext *C, wmOperator *op)
+{
+	ScrArea *sa= CTX_wm_area(C);
+	ARegion *ar= image_has_scope_region(sa);
+	
+	if(ar)
+		ED_region_toggle_hidden(C, ar);
+	
+	return OPERATOR_FINISHED;
+}
 
+void IMAGE_OT_scopes(wmOperatorType *ot)
+{
+	ot->name= "Scopes";
+	ot->idname= "IMAGE_OT_scopes";
+	
+	ot->exec= image_scopes;
+	ot->poll= ED_operator_image_active;
+	
+	/* flags */
+	ot->flag= 0;
+}
 

source/blender/editors/space_image/image_draw.c

@@ -204,6 +204,16 @@ void draw_image_info(ARegion *ar, int channels, int x, int y, char *cp, float *f
 	UI_DrawString(10, 10, str);
 }
 
+static inline int get_bin_float(float f)
+{
+	CLAMP(f, 0.0, 1.0);
+	
+	//return (int) (((f + 0.25) / 1.5) * 512);
+
+	return (int)(f * 511);
+}
+
+
 /* image drawing */
 
 static void draw_image_grid(ARegion *ar, float zoomx, float zoomy)
@@ -702,6 +712,11 @@ void draw_image_main(SpaceImage *sima, ARegion *ar, Scene *scene)
 	if(ibuf && ima && show_render)
 		draw_render_info(ima, ar);
 
+	/* histogram */
+	if (ibuf) {
+		histogram_update(&sima->hist, ibuf);
+	}
+	
 	/* XXX integrate this code */
 #if 0
 	if(ibuf) {

source/blender/editors/space_image/image_intern.h

@@ -44,6 +44,7 @@ struct bNodeTree;
 
 /* space_image.c */
 struct ARegion *image_has_buttons_region(struct ScrArea *sa);
+struct ARegion *image_has_scope_region(struct ScrArea *sa);
 
 /* image_header.c */
 void image_header_buttons(const struct bContext *C, struct ARegion *ar);
@@ -88,6 +89,7 @@ void draw_uvedit_main(struct SpaceImage *sima, struct ARegion *ar, struct Scene
 struct ImageUser *ntree_get_active_iuser(struct bNodeTree *ntree);
 void image_buttons_register(struct ARegionType *art);
 void IMAGE_OT_properties(struct wmOperatorType *ot);
+void IMAGE_OT_scopes(struct wmOperatorType *ot);
 
 #endif /* ED_IMAGE_INTERN_H */
 

source/blender/editors/space_image/image_ops.c

@@ -704,7 +704,8 @@ static int open_exec(bContext *C, wmOperator *op)
 
 	// XXX other users?
 	BKE_image_signal(ima, (sima)? &sima->iuser: NULL, IMA_SIGNAL_RELOAD);
-
+	WM_event_add_notifier(C, NC_IMAGE|NA_EDITED, ima);
+	
 	MEM_freeN(op->customdata);
 
 	return OPERATOR_FINISHED;

source/blender/editors/space_image/space_image.c

@@ -104,6 +104,33 @@ ARegion *image_has_buttons_region(ScrArea *sa)
 	return arnew;
 }
 
+ARegion *image_has_scope_region(ScrArea *sa)
+{
+	ARegion *ar, *arnew;
+	
+	for(ar= sa->regionbase.first; ar; ar= ar->next)
+		if(ar->regiontype==RGN_TYPE_PREVIEW)
+			return ar;
+	
+	/* add subdiv level; after buttons */
+	for(ar= sa->regionbase.first; ar; ar= ar->next)
+		if(ar->regiontype==RGN_TYPE_UI)
+			break;
+	
+	/* is error! */
+	if(ar==NULL) return NULL;
+	
+	arnew= MEM_callocN(sizeof(ARegion), "scopes for image");
+	
+	BLI_insertlinkafter(&sa->regionbase, ar, arnew);
+	arnew->regiontype= RGN_TYPE_PREVIEW;
+	arnew->alignment= RGN_ALIGN_RIGHT;
+	
+	arnew->flag = RGN_FLAG_HIDDEN;
+	
+	return arnew;
+}
+
 /* ******************** default callbacks for image space ***************** */
 
 static SpaceLink *image_new(const bContext *C)
@@ -135,6 +162,14 @@ static SpaceLink *image_new(const bContext *C)
 	ar->alignment= RGN_ALIGN_LEFT;
 	ar->flag = RGN_FLAG_HIDDEN;
 	
+	/* scopes */
+	ar= MEM_callocN(sizeof(ARegion), "buttons for image");
+	
+	BLI_addtail(&simage->regionbase, ar);
+	ar->regiontype= RGN_TYPE_PREVIEW;
+	ar->alignment= RGN_ALIGN_RIGHT;
+	ar->flag = RGN_FLAG_HIDDEN;
+	
 	/* main area */
 	ar= MEM_callocN(sizeof(ARegion), "main area for image");
 	
@@ -201,6 +236,7 @@ void image_operatortypes(void)
 
 	WM_operatortype_append(IMAGE_OT_toolbox);
 	WM_operatortype_append(IMAGE_OT_properties);
+	WM_operatortype_append(IMAGE_OT_scopes);
 }
 
 void image_keymap(struct wmKeyConfig *keyconf)
@@ -213,6 +249,7 @@ void image_keymap(struct wmKeyConfig *keyconf)
 	WM_keymap_add_item(keymap, "IMAGE_OT_save", SKEY, KM_PRESS, KM_ALT, 0);
 	WM_keymap_add_item(keymap, "IMAGE_OT_save_as", F3KEY, KM_PRESS, 0, 0);
 	WM_keymap_add_item(keymap, "IMAGE_OT_properties", NKEY, KM_PRESS, 0, 0);
+	WM_keymap_add_item(keymap, "IMAGE_OT_scopes", PKEY, KM_PRESS, 0, 0);
 	
 	keymap= WM_keymap_find(keyconf, "Image", SPACE_IMAGE, 0);
 	
@@ -278,8 +315,16 @@ static void image_refresh(const bContext *C, ScrArea *sa)
 	}
 }
 
+static void image_histogram_tag_refresh(ScrArea *sa)
+{
+	SpaceImage *sima= (SpaceImage *)sa->spacedata.first;
+	sima->hist.ok=0;
+}
+
 static void image_listener(ScrArea *sa, wmNotifier *wmn)
 {
+	SpaceImage *sima= (SpaceImage *)sa->spacedata.first;
+	
 	/* context changes */
 	switch(wmn->category) {
 		case NC_SCENE:
@@ -293,7 +338,11 @@ static void image_listener(ScrArea *sa, wmNotifier *wmn)
 			}
 			break;
 		case NC_IMAGE:
-			ED_area_tag_redraw(sa);
+			if (wmn->reference == sima->image) {
+				image_histogram_tag_refresh(sa);
+				ED_area_tag_refresh(sa);
+				ED_area_tag_redraw(sa);
+			}
 			break;
 		case NC_SPACE:	
 			if(wmn->data == ND_SPACE_IMAGE)
@@ -486,6 +535,31 @@ static void image_buttons_area_listener(ARegion *ar, wmNotifier *wmn)
 	}
 }
 
+/* *********************** scopes region ************************ */
+
+/* add handlers, stuff you only do once or on area/region changes */
+static void image_scope_area_init(wmWindowManager *wm, ARegion *ar)
+{
+	wmKeyMap *keymap;
+	
+	ED_region_panels_init(wm, ar);
+	
+	keymap= WM_keymap_find(wm->defaultconf, "Image Generic", SPACE_IMAGE, 0);
+	WM_event_add_keymap_handler(&ar->handlers, keymap);
+}
+
+static void image_scope_area_draw(const bContext *C, ARegion *ar)
+{
+	ED_region_panels(C, ar, 1, NULL, -1);
+}
+
+static void image_scope_area_listener(ARegion *ar, wmNotifier *wmn)
+{
+	/* context changes */
+	switch(wmn->category) {
+	}
+}
+
 /************************* header region **************************/
 
 /* add handlers, stuff you only do once or on area/region changes */
@@ -541,6 +615,16 @@ void ED_spacetype_image(void)
 	BLI_addhead(&st->regiontypes, art);
 
 	image_buttons_register(art);
+	
+	/* regions: statistics/scope buttons */
+	art= MEM_callocN(sizeof(ARegionType), "spacetype image region");
+	art->regionid = RGN_TYPE_PREVIEW;
+	art->minsizex= 220; // XXX
+	art->keymapflag= ED_KEYMAP_UI|ED_KEYMAP_FRAMES;
+	art->listener= image_scope_area_listener;
+	art->init= image_scope_area_init;
+	art->draw= image_scope_area_draw;
+	BLI_addhead(&st->regiontypes, art);
 
 	/* regions: header */
 	art= MEM_callocN(sizeof(ARegionType), "spacetype image region");

source/blender/makesdna/DNA_color_types.h

@@ -80,5 +80,16 @@ typedef struct CurveMapping {
 #define CUMA_DRAW_CFRA			4
 #define CUMA_DRAW_SAMPLE		8
 
+typedef struct Histogram {
+	int channels;
+	int x_resolution;
+	float data_r[512];
+	float data_g[512];
+	float data_b[512];
+	float min, max;
+	int ok;
+	int pad;
+} Histogram;
+
 #endif
 

source/blender/makesdna/DNA_space_types.h

@@ -32,6 +32,7 @@
 #define DNA_SPACE_TYPES_H
 
 #include "DNA_listBase.h"
+#include "DNA_color_types.h"		/* for Histogram */
 #include "DNA_vec_types.h"
 #include "DNA_outliner_types.h"		/* for TreeStoreElem */
 #include "DNA_image_types.h"	/* ImageUser */
@@ -43,6 +44,7 @@ struct Text;
 struct Script;
 struct ImBuf;
 struct Image;
+struct Histogram;
 struct SpaceIpo;
 struct BlendHandle;
 struct RenderInfo;
@@ -255,6 +257,8 @@ typedef struct SpaceImage {
 	float centx, centy;				/* storage for offset while render drawing */
 	
 	struct bGPdata *gpd;			/* grease pencil data */
+	
+	struct Histogram hist;			/* viewer histogram */
 } SpaceImage;
 
 typedef struct SpaceNla {

source/blender/makesdna/DNA_userdef_types.h

@@ -219,7 +219,7 @@ typedef struct ThemeSpace {
 	char handle_vertex_size;
 	char hpad[3];
 	
-	char pad[4];
+	char preview_back[4];
 	
 } ThemeSpace;
 

source/blender/makesrna/RNA_access.h

@@ -235,6 +235,7 @@ extern StructRNA RNA_GreasePencil;
 extern StructRNA RNA_Group;
 extern StructRNA RNA_Header;
 extern StructRNA RNA_HemiLamp;
+extern StructRNA RNA_Histogram;
 extern StructRNA RNA_HookModifier;
 extern StructRNA RNA_ID;
 extern StructRNA RNA_IDProperty;

source/blender/makesrna/intern/rna_color.c

@@ -229,11 +229,22 @@ static void rna_def_curvemapping(BlenderRNA *brna)
 	RNA_def_property_float_funcs(prop, NULL, "rna_CurveMapping_white_level_set", NULL);
 }
 
+static void rna_def_histogram(BlenderRNA *brna)
+{
+	StructRNA *srna;
+	PropertyRNA *prop;
+	
+	srna= RNA_def_struct(brna, "Histogram", NULL);
+	RNA_def_struct_ui_text(srna, "Histogram", "Statistical view of the levels of color in an image");
+	
+}
+
 void RNA_def_color(BlenderRNA *brna)
 {
 	rna_def_curvemappoint(brna);
 	rna_def_curvemap(brna);
 	rna_def_curvemapping(brna);
+	rna_def_histogram(brna);
 }
 
 #endif

source/blender/makesrna/intern/rna_space.c

@@ -333,6 +333,19 @@ static void rna_SpaceImageEditor_curves_update(Main *bmain, Scene *scene, Pointe
 	WM_main_add_notifier(NC_IMAGE, sima->image);
 }
 
+static void rna_SpaceImageEditor_histogram_update(Main *bmain, Scene *scene, PointerRNA *ptr)
+{
+	SpaceImage *sima= (SpaceImage*)ptr->data;
+	ImBuf *ibuf;
+	void *lock;
+	
+	ibuf= ED_space_image_acquire_buffer(sima, &lock);
+	histogram_update(&sima->hist, ibuf);
+	ED_space_image_release_buffer(sima, lock);
+	
+	WM_main_add_notifier(NC_IMAGE, sima->image);
+}
+
 
 /* Space Text Editor */
 
@@ -1004,6 +1017,12 @@ static void rna_def_space_image(BlenderRNA *brna)
 	RNA_def_property_pointer_sdna(prop, NULL, "cumap");
 	RNA_def_property_ui_text(prop, "Curves", "Color curve mapping to use for displaying the image.");
 	RNA_def_property_update(prop, NC_SPACE|ND_SPACE_IMAGE, "rna_SpaceImageEditor_curves_update");
+	
+	prop= RNA_def_property(srna, "histogram", PROP_POINTER, PROP_NONE);
+	RNA_def_property_pointer_sdna(prop, NULL, "hist");
+	RNA_def_property_struct_type(prop, "Histogram");
+	RNA_def_property_ui_text(prop, "Histogram", "Histogram for viewing image statistics");
+	RNA_def_property_update(prop, NC_SPACE|ND_SPACE_IMAGE, "rna_SpaceImageEditor_histogram_update");
 
 	prop= RNA_def_property(srna, "image_pin", PROP_BOOLEAN, PROP_NONE);
 	RNA_def_property_boolean_sdna(prop, NULL, "pin", 0);

source/blender/makesrna/intern/rna_ui_api.c

@@ -326,6 +326,10 @@ void RNA_api_ui_layout(StructRNA *srna)
 	api_ui_item_rna_common(func);
 	RNA_def_boolean(func, "expand", 0, "", "Expand button to show more detail.");
 	
+	func= RNA_def_function(srna, "template_histogram", "uiTemplateHistogram");
+	api_ui_item_rna_common(func);
+	RNA_def_boolean(func, "expand", 0, "", "Expand button to show more detail.");
+	
 	func= RNA_def_function(srna, "template_layers", "uiTemplateLayers");
 	api_ui_item_rna_common(func);
 	parm= RNA_def_pointer(func, "used_layers_data", "AnyType", "", "Data from which to take property.");

source/blender/makesrna/intern/rna_userdef.c

@@ -1202,6 +1202,12 @@ static void rna_def_userdef_theme_space_image(BlenderRNA *brna)
 	RNA_def_property_array(prop, 4);
 	RNA_def_property_ui_text(prop, "Active Vert/Edge/Face", "");
 	RNA_def_property_update(prop, 0, "rna_userdef_update");
+	
+	prop= RNA_def_property(srna, "scope_back", PROP_FLOAT, PROP_COLOR);
+	RNA_def_property_float_sdna(prop, NULL, "preview_back");
+	RNA_def_property_array(prop, 4);
+	RNA_def_property_ui_text(prop, "Scope region background color", "");
+	RNA_def_property_update(prop, 0, "rna_userdef_update");
 }
 
 static void rna_def_userdef_theme_space_seq(BlenderRNA *brna)