openCV AdaptiveThreshold versus Otsu Threshold. ROI
I'm tried to use both of the methods but it seems like Adaptive threshold seems to be giving a better result. I used
cvSmooth( temp, dst,CV_GAUSSIAN,9,9, 0);
on the original image then only i used the threshold.
Is there anything I can tweak with the Otsu method to make the image better like adaptive thresholding? And 1 more thing, there are some unwanted fingerprint residue on the side, any idea how i can dispose them off?
I read from a journal that by comparing the percentage of the white pixels in a self-defined square, I can get the ROI. However this method requires me to have a threshold value which can be found using OTSU method but I'm not too sure about AdaptiveThresholding.
cvAdaptiveThreshold( temp, dst, 255,CV_ADAPTIVE_THRESH_MEAN_C,CV_THRESH_BINARY,13, 1 );
Result :
cvThreshold(temp, dst, 0, 255, CV_THRESH_BINARY | CV_THRESH_OTSU);
To get rid of the unwanted background, you can do a simple masking operation. The Otsu threshold function provides a threshold value that cuts the foreground image from the background. Use that threshold value in order to create a binary mask by iterating through the entire input image, checking if the current pixel value is greater than the threshold, and setting it to 1 if true or 0 if it is false.
Then, you can apply the binary mask to the original image by a simple matrix multiplication operation or a bitwise shift operation to remove the background.
Try dividing the image into ROIs and apply otsu individually, then merge them back. Dividing strategy can be static or dynamic depending on the max illumination.
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