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+--- Thread: General pointer to start (/thread-27978.html)
General pointer to start - data4speed - Jun-30-2020
Let's say I have a large rectangular picture & each pixel s either 1 or 0 (white/black). How to write a function which takes 2 parameters:
1. Data structure holding the matix of black & white pixel
2. a tuple(x,y) for the position of the start pixel
This function should return the size of black and while area to which that pixel belongs.
any idea where to start?
RE: General pointer to start - DPaul - Jun-30-2020
Your question is somewhat unclear to me.
The first pixel is always at 0,0
And each pixel has 3+1 components, ([A]RGB), in the case of B&W they are (0,0,0) or (255,255,255)
You are probably defining the image as a bitmap and that holds the array of pixels.
The bitmap has a length and a width in pixels.
Paul
RE: General pointer to start - data4speed - Jul-01-2020
as an example, given the region of the image below and selecting the pixel in the middle as a starting point (2,2) (in bold), how do I calculate the area to which point (2,2) belongs?
0 0 0 0 0
0 1 1 0 0
0 1 1 0 0
0 1 0 1 0
0 0 0 0 0
RE: General pointer to start - DPaul - Jul-01-2020
Hi ,
So your question is to find a square region, when the middle is known (and the number of pixels in a row is not even.)
Top left is 0,0, (2 - 2 = 0)
Bottom right must be 4,4. (2 + 2 =4)
2 nested loops will find every pixel in the area.
If you are talking about a selection in a large bitmap, then we do not have enough data.
Paul