HW03

Bug:

for (int y=0; y<logoImg->height; y++) {  
    uchar* ptr1=(uchar*) (logoImg->imageData +y*logoImg->widthStep);
    uchar* ptr2=(uchar*) (mergeImg->imageData +(y+y1)*mergeImg->widthStep); 
    for (int x=0; x<logoImg->width; x++) {     
       ptr2[3*(x+x1)]=alpha*ptr1[3*(x+x1)] + (1-alpha)*ptr2[3*(x+x1)]; 
       ptr2[3*(x+x1)+1]=alpha*ptr1[3*(x+x1)+1] + (1-alpha)*ptr2[3*(x+x1)+1]; 
       ptr2[3*(x+x1)+2]=alpha*ptr1[3*(x+x1)+2] + (1-alpha)*ptr2[3*(x+x1)+2];    
    }
}   

應改成

for (int y=0; y<logoImg->height; y++) {  
    uchar* ptr1=(uchar*) (logoImg->imageData +y*logoImg->widthStep);
    uchar* ptr2=(uchar*) (mergeImg->imageData +(y+y1)*mergeImg->widthStep); 
    for (int x=0; x<logoImg->width; x++) {     
       ptr2[3*(x+x1)]=alpha*ptr1[3*x] + (1-alpha)*ptr2[3*(x+x1)]; 
       ptr2[3*(x+x1)+1]=alpha*ptr1[3*x+1] + (1-alpha)*ptr2[3*(x+x1)+1]; 
       ptr2[3*(x+x1)+2]=alpha*ptr1[3*x+2] + (1-alpha)*ptr2[3*(x+x1)+2];    
    }
}   

心得:
這次的作業很好玩，了解運作方式後很快就改好了。
把LOGO放進影片感覺很實用，希望可以學到更多東西。