Detecting pixel coordinates on the straight line determined by two points

　　Two pixels on the image to determine a straight line, can be done to find out what the position of these pixels by linear equation? We would expect a straight line equation calculation, but the position of the image pixel coordinates are integer values, by y = k * x + b y is calculated may be a decimal, even if the y do rounding operation, can not well describe points on a straight line, it may lead to describe a straight line in a "dotted line" form, such as a linear equation y = 0.2 * x + 0.3:

　　　　　　　　　　0.2 + 1 * 0.5 = 0.3, coordinates (1, 0.5);

　　　　　　　　　　0.2 * 2 + 0.7 = 0.3, coordinates (2,0.7);

　　　　　　　　　　0.9 + 0.3 * 3 = 0.2, coordinates (3.0.9).

 Describe a straight line as shown in FIG tend, as shown below.

                                           

                                Videos straight line function of the conventional method of drawing a straight line matlab

　　Had also think it is a very easy to solve the problem, but to no avail trace out a straight line, a bit rough search online information in this regard is very small. Therefore, the authors give a quick and easy method of calculation, the pixel position on these lines to find out.

    We know A (x1, y1), B (x2, y2) two points can be determined and the slope k AB linear equation y = k * x + b coordinate values ​​of the intercept B;

Algorithm steps:

　　1. The abscissa and ordinate respectively calculate the difference between two points:

   　　 deltaH = abs(y1 - y2);

    　　deltaW = abs(x1 - x2);

    2. Set the loop variable range , if deltaH <deltaW, the range of the argument [x1, x2] (assuming x1 <x2), and vice versa argument range [y1, y2];

    3. When deltaH <DeltaW time , select A, B do any starting point, respectively, when calculated from the abscissa variable is j, the ordinate is i, the difference between the intercept of the linear equation and b Tmpb obtained according to , corresponding to a minimum difference value from the position variable i is the ordinate, the code is (Coor code is stored on a straight line pixel positions):

for J = X1: X2 
            Hb of = Y1 - . 1 ;% point A as the starting point 
            of He = Y1 + . 1 ; 
            H = 0 ; 
            W is = 0 ; 
            Min = 1000 ;        
             for I = Hb of: of He 
                Tmpb = I - K * J; 
                Delta = ABS (B - Tmpb);
                 IF Delta < Min 
                    Min = Delta;
                    H= I; 
                    W is = J; 
                End 
            End 
            IF H ~ = 0 && W is ~ = 0 
                the Num = + the Num . 1 ;% on the line number of pixels 
                of Coor (the Num, . 1 ) = H;% on a straight line the pixel coordinates of the position 
                of Coor ( NUM, 2 ) = W is; 
                Y1 = H; 
            End                 
        End

 　　When deltaH> deltaW

for I = Y1: Y2 
            Min = 1000 ; 
            H = 0 ; 
            W is = 0 ; 
            Wb = X1 - . 4 ;% independent variable range can be set according to the linear characteristic 
            We = X1 + . 4 ;
             for J = Wb: We 
                Tmpb = I - K * J; 
                Delta = ABS (B - Tmpb);
                 IF Delta < Min 
                    Min =  Delta;
                    H= i;
                    W = j;
                end
            end
            if H ~= 0 && W ~= 0
                Num = Num + 1;
                Coor(Num,1) = H;
                Coor(Num,2) = W;
                x1 = W;
            end
        end

This article is drawn from a straight line

Reproduced in: https: //www.cnblogs.com/ImageVision/archive/2012/11/17/2775196.html