Revision history [back]

here's the problem:

 cvtColor(inputImg,inputImg,CV_8UC1);   // CV_8UC1 is the wrong constant.

what you need instead is:

cvtColor(inputImg,inputImg,COLOR_BGR2GRAY);

CV_8UC1 evaluates to 0, so you did the same as:

cvtColor(inputImg,inputImg, COLOR_BGR2BGRA);

thus equalizeHist complains, - the input is still 3-channel, not 1channel.

but, since you already got a grayscale image above, why not use that instead ?

Mat gray;
// i'm sure, you do *not* want alpha to influence your grayscale.
if(img.channels() > 0){
   cvtColor(img, gray, CV_BGR2GRAY);
} 
else{       
    gray = img;
}

Mat inputImg;
float scale = img.cols/(float)scaledWidth;
if(img.cols > scaledWidth){
    int scaledHeight = cvRound(img.rows / scale);
    resize(gray, inputImg, Size(scaledWidth, scaledHeight)); //use grayscale img  
}
else{
    inputImg = gray; //use grayscale img 
}
//cvtColor(inputImg, inputImg, COLOR_BGR2GRAY);    // no more needed.

Mat equalizedImg;
equalizeHist(inputImg, equalizedImg);

here's the problem:

 cvtColor(inputImg,inputImg,CV_8UC1);   // CV_8UC1 is the wrong constant.

what you need instead is:

cvtColor(inputImg,inputImg,COLOR_BGR2GRAY);

CV_8UC1 evaluates to 0, so you did the same as:

cvtColor(inputImg,inputImg, COLOR_BGR2BGRA);

thus equalizeHist complains, - the input is still 3-channel, not 1channel.

but, since you already got a grayscale image above, why not use that instead ?

Mat gray;
// i'm sure, you do *not* want alpha to influence your grayscale.
if(img.channels() > 0){
1){
   cvtColor(img, gray, CV_BGR2GRAY);
} 
else{       
    gray = img;
}

Mat inputImg;
float scale = img.cols/(float)scaledWidth;
if(img.cols > scaledWidth){
    int scaledHeight = cvRound(img.rows / scale);
    resize(gray, inputImg, Size(scaledWidth, scaledHeight)); //use grayscale img  
}
else{
    inputImg = gray; //use grayscale img 
}
//cvtColor(inputImg, inputImg, COLOR_BGR2GRAY);    // no more needed.

Mat equalizedImg;
equalizeHist(inputImg, equalizedImg);

here's the problem:

 cvtColor(inputImg,inputImg,CV_8UC1);   // CV_8UC1 is the wrong constant.

what you need instead is:

cvtColor(inputImg,inputImg,COLOR_BGR2GRAY);

CV_8UC1 evaluates to 0, so you did the same as:

cvtColor(inputImg,inputImg, COLOR_BGR2BGRA);

thus equalizeHist complains, - the input is still 3-channel, not 1channel.

but, since you already got a grayscale image above, why not use that instead ?

Mat gray;
// i'm sure, you do *not* want alpha to influence your grayscale.
if(img.channels() > 1){
== 3){
    cvtColor(img, gray, CV_BGR2GRAY);
} 
}
else if(img.channels() == 4){
    cvtColor(img, gray, CV_BGRA2GRAY);
}
else{       
    gray = img;
}

Mat inputImg;
float scale = img.cols/(float)scaledWidth;
if(img.cols > scaledWidth){
    int scaledHeight = cvRound(img.rows / scale);
    resize(gray, inputImg, Size(scaledWidth, scaledHeight)); //use grayscale img  
}
else{
    inputImg = gray; //use grayscale img 
}
//cvtColor(inputImg, inputImg, COLOR_BGR2GRAY);    // no more needed.

Mat equalizedImg;
equalizeHist(inputImg, equalizedImg);