From 98a4daf9aff1b54c0ca76d79524707a1da9e70f3 Mon Sep 17 00:00:00 2001
From: Emil Martinec <ejmartin@uchicago.edu>
Date: Sun, 12 Dec 2010 07:47:41 -0600
Subject: [PATCH] Fix for smoother zoomed out preview images.  Instead of point
 sampling every 'skip' number of pixels, pixels are binned in 'skip*skip' size
 blocks.

---
 rtengine/rawimagesource.cc | 30 +++++++++++++++++++++++-------
 rtengine/stdimagesource.cc | 20 +++++++++++++++-----
 2 files changed, 38 insertions(+), 12 deletions(-)

diff --git a/rtengine/rawimagesource.cc b/rtengine/rawimagesource.cc
index dc31e81ea..c587962de 100644
--- a/rtengine/rawimagesource.cc
+++ b/rtengine/rawimagesource.cc
@@ -241,19 +241,35 @@ void RawImageSource::getImage (ColorTemp ctemp, int tran, Image16* image, Previe
     unsigned short* grn  = new unsigned short[imwidth];
     unsigned short* blue = new unsigned short[imwidth];
 
+	float rtot,gtot,btot;
+	int boxarea=SQR(pp.skip);
     for (int i=sy1,ix=0; ix<imheight; i+=pp.skip, ix++) {
         if (ri->isBayer()) {
             for (int j=0,jx=sx1; j<imwidth; j++,jx+=pp.skip) {
-                red[j] = CLIP(rm*this->red[i][jx]);
-                grn[j] = CLIP(gm*this->green[i][jx]);
-                blue[j] = CLIP(bm*this->blue[i][jx]);
+				rtot=gtot=btot=0;
+				for (int m=0; m<pp.skip; m++)
+					for (int n=0; n<pp.skip; n++) {
+						rtot += this->red[i+m][jx+n];
+						gtot += this->green[i+m][jx+n];
+						btot += this->blue[i+m][jx+n];
+					}
+                red[j] = CLIP(rm*rtot/boxarea);
+                grn[j] = CLIP(gm*gtot/boxarea);
+                blue[j] = CLIP(bm*btot/boxarea);
             }
         } else {
             for (int j=0,jx=sx1; j<imwidth; j++,jx+=pp.skip) {
-                red[j]  = CLIP(rm*rawData[i][jx*3+0]);
-                grn[j]  = CLIP(gm*rawData[i][jx*3+1]);
-                blue[j] = CLIP(bm*rawData[i][jx*3+2]);
-
+				rtot=gtot=btot=0;
+				for (int m=0; m<pp.skip; m++)
+					for (int n=0; n<pp.skip; n++) {
+						rtot += rawData[i+m][(jx+n)*3+0];
+						gtot += rawData[i+m][(jx+n)*3+1];
+						btot += rawData[i+m][(jx+n)*3+2];
+					}				
+                red[j] = CLIP(rm*rtot/boxarea);
+                grn[j] = CLIP(gm*gtot/boxarea);
+                blue[j] = CLIP(bm*btot/boxarea);
+				
             }
         }
                 
diff --git a/rtengine/stdimagesource.cc b/rtengine/stdimagesource.cc
index 695814790..e29462d39 100644
--- a/rtengine/stdimagesource.cc
+++ b/rtengine/stdimagesource.cc
@@ -182,12 +182,22 @@ void StdImageSource::getImage_ (ColorTemp ctemp, int tran, Image16* image, Previ
     unsigned short* grn  = new unsigned short[imwidth];
     unsigned short* blue = new unsigned short[imwidth];
         
+	float rtot,gtot,btot;
+	int boxarea=SQR(pp.skip);
     for (int i=istart; i<iend; i+=skip, ix++) {
-    for (int j=0,jx=sx1; j<imwidth; j++,jx+=pp.skip) {
-            red[j]  = img->r[i][jx];
-            grn[j]  = img->g[i][jx];
-            blue[j] = img->b[i][jx];
-        }        
+		for (int j=0,jx=sx1; j<imwidth; j++,jx+=pp.skip) {
+			rtot=gtot=btot=0;
+			for (int m=0; m<pp.skip; m++)
+				for (int n=0; n<pp.skip; n++) {
+					rtot += img->r[i+m][jx+n];
+					gtot += img->g[i+m][jx+n];
+					btot += img->b[i+m][jx+n];
+				}
+			
+			red[j]  = round(rtot/boxarea);
+            grn[j]  = round(gtot/boxarea);
+            blue[j] = round(btot/boxarea);
+		}        
 //        if (hrp.enabled)
 //            hlRecovery (red, grn, blue, i, sx1, sx2, pp.skip);