Thresholding image in OpenCV for a range of max and min values

Question

I like to threshold an image within a range max and min value and fill the rest with 255 for those pixel values out of that range. I can't find such threshold in OpenCV document here. Thanks

Answer 1

inRange(src, lowerBound, upperBound, dst);
bitwise_not(src, src);

Answer 2

The basic:

threshold(src, dst, threshold value, max value, threshold type);

where

src_gray: Our input image
dst: Destination (output) image
threshold_value: The thresh value with respect to which the thresholding operation is made
max_BINARY_value: The value used with the Binary thresholding operations (to set the chosen pixels)
threshold_type: One of the 5 thresholding operations. 

so for example,

threshold(image, fImage, 125, 255, cv::THRESH_BINARY);

means every value below 125, will be set to zero, and above 125 to the value of 255.

If what you are looking for is to have a particular range, for instance 50 to 150, I would recommend you do a for loop, and check and edit the pixels yourself. It is very simple. Take a look at this c++ code of mine:

for (int i=0; i< image.rows; i++)
    { 
        for (int j=0; j< image.cols; j++)
        {
            int editValue=image.at<uchar>(i,j);

            if((editValue>50)&&(editValue<150)) //check whether value is within range.
            {
                image.at<uchar>(i,j)=255;
            }
            else
            {
                image.at<uchar>(i,j)=0;
            }
        }
    }

Hope I solved your problem. Cheers(: Do comment if you need more help.