What is the use of cvGetRows() function in OpenCV? -


when should use function. can explain me example?

according documentation, itreturns array row or row span. returns rows specified.

i explain of python terminal:

load image in grayscale mode , check width , height.

>>> import cv2.cv cv >>> img = cv.loadimage('approx2.jpg',0) >>> img <iplimage(nchannels=1 width=300 height=300 widthstep=300 )>

see, image 300x300 size. below image.

enter image description here

taking sum pixels,

>>> cv.sum(img) (1252271.0, 0.0, 0.0, 0.0)

now apply our first function, cv.getrow()

>>> row = cv.getrow(img,150) >>> row <cvmat(type=42424000 8uc1 rows=1 cols=300 step=300 )> >>> cv.sum(row) (14279.0, 0.0, 0.0, 0.0)

i took 150th row , took sum of elements in row. see resulting image has height = 1.

now taking function cv.getrows().

>>> rows = cv.getrows(img,0,150) >>> rows <cvmat(type=42424000 8uc1 rows=150 cols=300 step=300 )> >>> cv.sum(rows) (802501.0, 0.0, 0.0, 0.0)

i took rows upto 150th. see height 150. check out image below:

enter image description here

now there fourth argument on function delta_row can used increment. select rows increment of step size mentioned, skipping in between. ie if specified, the function extracts every delta_row -th row start_row , (but not including) end_row .

>>> rows = cv.getrows(img,0,300,5) >>> rows <cvmat(type=42420000 8uc1 rows=60 cols=300 step=1500 )>

see, height 30 because extracts every 5th row.

result below :

enter image description here

similar case cv.getcol() , cv.getcols().


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