cv.integral - MATLAB File Help |
Calculates the integral of an image
s = cv.integral(src)
[s, sqsum, tilted] = cv.integral(src)
[...] = cv.integral(src, 'OptionName',optionValue, ...)
W x H
, 8-bit, 16-bit or floating-point
(single
or double
).(W+1) x (H+1)
, 32-bit integer or floating-point
(single
or double
).(W+1) x (H+1)
,
double-precision floating-point array.(W+1) x (H+1)
array with the same data type as s
.int32
, single
, or double
. default -1single
or double
. default -1The function calculates one or more integral images for the source image as follows:
s(X,Y) = sum_{x<X,y<Y} src(x,y)
sqsum(X,Y) = sum_{x<X,y<Y} src(x,y)^2
tilted(X,Y) = sum_{y<Y,abs(x-X+1)<=Y-y-1} src(x,y)
Using these integral images, you can calculate sum, mean, and standard deviation over a specific up-right or rotated rectangular region of the image in a constant time, for example:
sum_{x_1 <= x < x_2, y_1 <= y < y_2} src(x,y)
= s(x_2, y_2) - s(x_1, y_2) - s(x_2, y_1) + s(x_1, y_1)
It makes possible to do a fast blurring or fast block correlation with a variable window size, for example. In case of multi-channel images, sums for each channel are accumulated independently.