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How to visualize a depth image

asked 2012-12-12 06:27:43 -0500

alykhantejani gravatar image

Hi,

I am using a dataset in which it has images where each pixel is a 16 bit unsigned int storing the depth value of that pixel in mm. I am trying to visualize this as a greyscale depth image by doing the following:

cv::Mat depthImage; 
depthImage = cv::imread("coffee_mug_1_1_1_depthcrop.png", CV_LOAD_IMAGE_ANYDEPTH | CV_LOAD_IMAGE_ANYCOLOR ); // Read the file 
depthImage.convertTo(depthImage, CV_32F); // convert the image data to float type   
namedWindow("window");
float max = 0;
for(int i = 0; i < depthImage.rows; i++){
    for(int j = 0; j < depthImage.cols; j++){
        if(depthImage.at<float>(i,j) > max){
            max = depthImage.at<float>(i,j);
        }
    }   
}
cout << max << endl;


float divisor = max / 255.0;
cout << divisor << endl;
for(int i = 0; i < depthImage.rows; i++){
    for(int j = 0; j < depthImage.cols; j++){
        cout << depthImage.at<float>(i,j) << ", ";
        max = depthImage.at<float>(i,j) /= divisor;
        cout << depthImage.at<float>(i,j) << endl;
    }   
}


imshow("window", depthImage);
waitKey(0);

However, it is only showing two colours this is because all of the values are close together i.e. in the range of 150-175 + the small values which show up black (see below).

RGB image greyscale image

Is there a way to normalize this data such that it will show various grey levels to highlight these small depth differences?

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Comments

Try histogram equalization

Haris gravatar imageHaris ( 2012-12-12 06:38:51 -0500 )edit

Can you provide a code sample? Or link to tutorial, I am fairly new to the library

alykhantejani gravatar imagealykhantejani ( 2012-12-12 06:46:34 -0500 )edit

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answered 2012-12-12 06:51:18 -0500

Haris gravatar image

updated 2012-12-12 06:52:50 -0500

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Asked: 2012-12-12 06:27:43 -0500

Seen: 2,835 times

Last updated: Dec 12 '12