From f7fcf8cdea57a043b99d90549407195ea1148042 Mon Sep 17 00:00:00 2001
From: Tim Redfern <tim@herge.(none)>
Date: Tue, 16 Jul 2013 15:55:57 +0100
Subject: alpha not yet working

---
 rotord/cvimage.cpp | 62 ++++++++++++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 60 insertions(+), 2 deletions(-)

(limited to 'rotord/cvimage.cpp')

diff --git a/rotord/cvimage.cpp b/rotord/cvimage.cpp
index 3a070a9..2130fc6 100644
--- a/rotord/cvimage.cpp
+++ b/rotord/cvimage.cpp
@@ -3,7 +3,6 @@
 using namespace std;
 
 namespace Rotor {
-	//believe these still work, don't know if these optimisations are better than opencvs..
 	Image & Image::operator+=(const Image &other) {
 		if (other.w!=w||other.h!=h) {
 			cerr<<"Rotor: cannot add images with different sizes! (wanted "<<w<<"x"<<h<<", got "<<other.w<<"x"<<other.h<<")"<<endl;
@@ -28,12 +27,71 @@ namespace Rotor {
 		}
 		else {
 			for (int i=0;i<w*h*3;i++){
-				//creates rainbow overload
+				//creates rainbow overload, openCV doesn't do this
 				RGBdata[i]=(unsigned char)(((int)other.RGBdata[i]+(int)RGBdata[i]));
 			}
 		}
 		return *this;
 	}
+	Image & Image::alpha_blend(const Image &other) {
+		if (other.w!=w||other.h!=h) {
+			cerr<<"Rotor: cannot blend images with different sizes! (wanted "<<w<<"x"<<h<<", got "<<other.w<<"x"<<other.h<<")"<<endl;
+			//why not??
+		}
+		else if (!other.alpha.data){
+			//default to full on alpha
+			rgb=other.rgb.clone();
+		}
+		else {
+			//overlay the other image based on its alpha values
+			//https://gist.github.com/Brick85/5009046 - this is a dumb way to do it?
+			//how to invert a matrix?
+			//'invert' is matrix invert - different
+			//subtract from a scalar (1) ?
+			//vector<cv::Mat> ichans,ochans;
+			//vector<cv::Mat> compchans;
+			//cv::split(rgb,ichans);
+			//cv::split(other.rgb,ochans);
+			//uint8_t b=0xFF;
+			//cv::Mat iA=b-other.alpha;
+			//cv::Mat iA=cv::Mat(h,w,CV_8UC1);
+			//for (int i=0;i<w*h;i++) iA.data[i]=(uint8_t)0xFF-other.alpha.data[i];
+			//for (int i=0;i<3;i++) {
+			//	compchans.push_back((ichans[i]/iA)+(ochans[i]/other.alpha)); //.mul(iA,1.0/255.0)); //+ochans[i].mul(other.alpha));
+			//}
+			//merge(compchans,rgb);
+			//rgb+=other.rgb;
+			for (int i=0;i<w*h*3;i++) {
+				rgb.data[i]=(uint8_t)(((((int)rgb.data[i])*(0xFF-((int)other.alpha.data[i/3])))>>8)+((((int)other.rgb.data[i])*((int)other.alpha.data[i/3])>>8)));
+
+			}
+		}
+
+		return *this;
+	}
+	Image & Image::alpha_merge(const Image &other) {
+		//converts the incoming image to monochrome and inserts it into the alpha channel of this image
+		if (other.w!=w||other.h!=h) {
+			cerr<<"Rotor: cannot merge alpha with different size! (wanted "<<w<<"x"<<h<<", got "<<other.w<<"x"<<other.h<<")"<<endl;
+		}
+		else {
+			alpha=cv::Mat(h,w,CV_8UC1);
+			//cv::cvtColor(other.rgb,alpha,CV_RGB2GRAY);
+			for (int i=0;i<w*h;i++) {
+				uint8_t v=0;
+				for (int j=0;j<3;j++){
+					v+=pixels.mono_weights[j][other.rgb.data[i*3+j]];
+				}
+				alpha.data[i]=v;
+			}
+		}
+		return *this;
+	}
+	//channel rearrangement
+	//RGBAZ - these are channels 0-4
+	//HSB - can also have these virtual channels 5-7
+	//convert channels- int outChannel[5] - {0,1,2,-5,4} - this mapping sends inverted brightness to alpha
+
 	//scalar operations allocate a new image.
 	//maybe this could not be the case if the data is owned by this image?
 	//need to look into auto_ptr
-- 
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