Hi all!
I'm having an 16-Bit Gray scale Image. I want to reduce the Grey values of the pixels in it. I tried to use LUT but it seems that it can only work for 8-Bit Images. What is the efficient way to reduce a matrix through LUT? Any help is appreciated!
Thank you for helping me to solve this problem! Here is my code for 16-Bit Look up table based reduction. hope this might be useful for someone!
main()
{
Size Img_Size(320,240);
Mat Img_Source_16(Size(320,240),CV_16UC1,Scalar::all(0));
Mat Img_Destination_16(Size(320,240),CV_16UC1,Scalar::all(0));
unsigned short LookupTable[4096];
for (int i = 0; i < 4096; i++)
{
LookupTable[i]= 4096-i;
}
int i=0;
for (int Row = 0; Row < Img_Size.height; Row++)
{
for (int Col = 0; Col < Img_Size.width; Col++)
{
Img_Source_16.at<short>(Row,Col)= i;
i++;
if(i>=4095)
i=0;
}
}
imshow("Img_Source",Img_Source_16);
t1.start();
Img_Destination_16= ScanImageAndReduceC_16UC1(Img_Source_16.clone(),LookupTable);
imshow("Img_Destination",Img_Destination_16);
t1.stop();
}
Mat& ScanImageAndReduceC_16UC1(Mat& I, const unsigned short* const table)
{
// accept only char type matrices
CV_Assert(I.depth() != sizeof(uchar));
int channels = I.channels();
int nRows = I.rows;
int nCols = I.cols * channels;
if (I.isContinuous())
{
nCols *= nRows;
nRows = 1;
}
int i,j;
unsigned short* p = (unsigned short*)I.data;
for( unsigned int i =0; i < nCols*nRows; ++i)
*p++ = table[*p];
return I;
}
Nice one :) Might up to making a PR and integrating this in OpenCV?
It's very easy to implement a custom function for LUT coloring.
See my answer in this topic: http://answers.opencv.org/question/50781/false-coloring-of-grayscale-image/
In short: you create a RGB lookup table of desired length (65536 in this case), then for each gray pixel P to get the false colored pixel C:
C[0]=LUT[P][0];
C[1]=LUT[P][1];
C[2]=LUT[P][2];
Asked: 2014-11-24 00:06:13 -0600
Seen: 5,675 times
Last updated: Dec 01 '14
I guess your option is either to convert to 8 bit first or implement the function of 18 bit. Afaik it doesn't exist yet but it should be quite similar to the 8 bit case. As to the answers, they will appear, the accept page is currently bugged. Devs are fixing it and putting the hosting somewhere else.