Python3 Pillow Get all pixels on a line

Question

I need to get the pixel values along a line, I'm using Python3 and Pillow. In opencv there is such a thing as a LineIterator which will return all of the appropriate pixels between two points, but I haven't found anything like that in Pillow's docs. I'm using Pillow because I had originally saw this post which said that python3 didn't have opencv support, I know that it's from 2012 but that seems to be confirmed by this post which I believe is from this year, given that there is no year on the posts. But when I run pip3.2 search opencv I can see a pyopencv but am unable to install it, it says that it could not find an appropriate version (probably a python2.x to python3.x issue). My preferred solutions are ordered as follows: - A way to properly install opencv for python3 (preferably opencv 2.4.8) - A way to get the pixels of a line using just Pillow - Simple solutions that don't involve extra libraries (numpy/scipy) - Everything else

Accepted Answer

I ended up going with a straight python solution based on Xiaolin Wu's line algorithm

```
def interpolate_pixels_along_line(x0, y0, x1, y1):
    """Uses Xiaolin Wu's line algorithm to interpolate all of the pixels along a
    straight line, given two points (x0, y0) and (x1, y1)

Wikipedia article containing pseudo code that function was based off of:
        http://en.wikipedia.org/wiki/Xiaolin_Wu's_line_algorithm
    """
    pixels = []
    steep = abs(y1 - y0) > abs(x1 - x0)

# Ensure that the path to be interpolated is shallow and from left to right
    if steep:
        t = x0
        x0 = y0
        y0 = t

t = x1
        x1 = y1
        y1 = t

if x0 > x1:
        t = x0
        x0 = x1
        x1 = t

t = y0
        y0 = y1
        y1 = t

dx = x1 - x0
    dy = y1 - y0
    gradient = dy / dx  # slope

# Get the first given coordinate and add it to the return list
    x_end = round(x0)
    y_end = y0 + (gradient * (x_end - x0))
    xpxl0 = x_end
    ypxl0 = round(y_end)
    if steep:
        pixels.extend([(ypxl0, xpxl0), (ypxl0 + 1, xpxl0)])
    else:
        pixels.extend([(xpxl0, ypxl0), (xpxl0, ypxl0 + 1)])

interpolated_y = y_end + gradient

# Get the second given coordinate to give the main loop a range
    x_end = round(x1)
    y_end = y1 + (gradient * (x_end - x1))
    xpxl1 = x_end
    ypxl1 = round(y_end)

# Loop between the first x coordinate and the second x coordinate, interpolating the y coordinates
    for x in range(xpxl0 + 1, xpxl1):
        if steep:
            pixels.extend([(math.floor(interpolated_y), x), (math.floor(interpolated_y) + 1, x)])

else:
            pixels.extend([(x, math.floor(interpolated_y)), (x, math.floor(interpolated_y) + 1)])

interpolated_y += gradient

# Add the second given coordinate to the given list
    if steep:
        pixels.extend([(ypxl1, xpxl1), (ypxl1 + 1, xpxl1)])
    else:
        pixels.extend([(xpxl1, ypxl1), (xpxl1, ypxl1 + 1)])

return pixels
```

Python3 Pillow Get all pixels on a line

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