[Python] Vertical line in my graphing rendering function

I am working on a graphing calculator and when I graph certain functions (e.g y=abs(x)) there is a vertical line in the middle. This only happens on certain resolutions. It happens with other functions as well such as certain parabolas.

from PIL import Image
from numba import vectorize, float64, njit
import numpy as np
import numexpr as ne
from time import time
from timeit import timeit

def generate_img(equation, resolution, xbound, ybound, color) -> Image.Image:
equation_sides = equation.split("=")


xbound_dist = abs(xbound[0]) + abs(xbound[1])
ybound_dist = abs(ybound[0]) + abs(ybound[1])

xstep = xbound_dist / resolution[0]
ystep = ybound_dist / resolution[1]

xstart = xbound[0] - xstep
ystart = ybound[1] - ystep



pixels = np.arange((resolution[0] + 2) * (resolution[1] + 2), dtype=np.int32)

x = get_x(np.float64(xstart), np.float64(xstep), np.int32(resolution[0] + 2), pixels)
y = get_y(np.float64(ystart), np.float64(ystep), np.int32(resolution[0] + 2), pixels)


pixels_shape = (resolution[1] + 2, resolution[0] + 2)
pixels = ne.evaluate(f"({equation_sides[0]})-({equation_sides[1]})", local_dict={"x": x, "y": y, "i": 1j}).reshape(pixels_shape)

mask = get_imag(pixels[1:resolution[1] + 1, 1: resolution[0] + 1])
pixels = abs(pixels)
pixels = pixels.astype(np.float64)

main_area = pixels[1:resolution[1]+1, 1:resolution[0]+1]
north = pixels[0:resolution[1], 1:resolution[0]+1]
south = pixels[2:resolution[1]+2, 1:resolution[0]+1]
west = pixels[1:resolution[1]+1, 0:resolution[0]]
east = pixels[1:resolution[1]+1, 2:resolution[0]+2]
north_east = pixels[0:resolution[1], 2:resolution[0]+2]
north_west = pixels[0:resolution[1], 0:resolution[0]]
south_east = pixels[2:resolution[1]+2, 2:resolution[0]+2]
south_west = pixels[2:resolution[1]+2, 0:resolution[0]]

pixels = light_up_pixels(
main_area,
north,
south,
west,
east,
north_east,
north_west,
south_east,
south_west
)

shape = Image.fromarray(pixels * mask)
img = Image.new("RGB", resolution, color)
img.putalpha(shape)
return img

@vectorize(['bool(float64)', 'bool(complex128)'])
def get_imag(pixel):
return abs(pixel.imag) < 0.01

@vectorize(['float64(float64, float64, int32, int32)'])
def get_x(xstart, xstep, xres, p):
return xstart + (p % xres) * xstep

@vectorize(['float64(float64, float64, int32, int32)'])
def get_y(ystart, ystep, xres, p):
return ystart - (p // xres) * ystep

@vectorize(['boolean(float64, float64, float64, float64, float64, float64, float64, float64, float64)'])
def light_up_pixels(main, north, south, west, east, north_east, north_west, south_east, south_west):
count = 0
count += main < north
count += main < south
count += main < west
count += main < east
count += main < north_east
count += main < north_west
count += main < south_east
count += main < south_west
return count >= 6


equation = "y=abs(x)"
generate_img(equation, (10, 20), (-10, 10), (-10, 10), (255, 0, 0)).show()


the graph result using the current code I feel like I've tried everything but it's still not working

I don't have the correct image as I my program does not currently work correctly, there should not be a vertical line under the corner of the abs function. it should look like an upside down '^' not a 'Y'

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