Confused about the pixels on the screen

Dear all,

I am confused about depicting a pixel on the screen.

Is each individual pixel treated as a small square? If this is the case, a coordinate (e.g. [100 100]) only depicts one corner of the specific pixel (top-left corner?), is this correct?

Let's say I want to depict a rectangle onto the screen. Assume the destinationRect is [100 100 200 200], then how many pixels will the rectangle contain? 101*101? or 100*100?

Could any one please help me with this problem?

Best, Pan

Answer 1

[Vidhi Agarwal]

Hi @Pan,

Yes, each pixel is treated as a unit square, typically with integer-indexed top-left corner coordinates. Coordinate [100, 100] refers to the top-left corner of the pixel at row 100, column 100 (if using image coordinate convention) or x = 100, y = 100 (if using screen coordinates). In MATLAB, this coordinate refers to the top-left corner of the pixel. For a rectangle defined as [100 100 200 200], how many pixels are included depends on the interpretation of the coordinates.

MATLAB often uses the format: [x1, y1, x2, y2]

But in many MATLAB functions (e.g., rectangle), the form is instead: [x, y, width, height]

If [100 100 200 200] is interpreted as [x1 y1 x2 y2], then:

• Pixels included = (200 - 100 + 1)^2 = 10201

If interpreted as [x, y, width, height]:

• Pixels included = 200 * 200 = 40000

Hope this helps!