Ytdyklly

please help speed this up. (I am a multiprocessing noob):

from multiprocessing import Pool

from numpy import real, imag, abs

from PIL import Image

from threading import Thread

import os

resolution = 15000 # not direct resolution, but proportional to it

resolution100=int(resolution*0.01)

size = tuple([100, resolution*2])

color = tuple([1])

start_r = 0

stop_r= 0  

"""r is real and i is imaginary where practical"""





def process_job(r):

    """creates a slice of the set"""

    img = Image.new('1', size, color)  # B&W image

    print(int(r + 2*resolution100+1), 'of', int(resolution100 *3))

    r = r * 100

    for rval in range(100):

        for i in range(-resolution, resolution, 1):

            if abrot(((r + rval) / resolution), (i / resolution * 1j)):

                try:

                    img.putpixel((rval, i + resolution,), 0)

                except:

                    print(r, rval, i + resolution)

    img.save(('z_images/' + str(resolution) + '/' + str(int(r/100)+int(resolution*.02)) + '.png'))





def abrot(x, y):

    """tests a point"""

    c = (x + y)

    z = 0 + 0j

    for _ in range(5):

        z = z * z + c

    if abs(real(z*z+c))>=2and abs(imag(z*z+c))>=2:

        return False

    for _ in range(int(resolution / 10)):

        if real(z + 0.0001) > float(real(z*z+c)) > real(z - 0.0001):

            return True

        z = z * z + c

        if abs(real(z)) >= 2:

            return False

    return True





def doItAll(resolution):

    with Pool(4, maxtasksperchild=10) as p:

        p.map(process_job, range((-2 * resolution100+start_r), resolution100-stop_r, 1))





if __name__ == '__main__':

    try:

        os.mkdir('/Users/milo/PycharmProjects/mandlebrot/venv/z_images/'+str(resolution)+'/')  # I know I misspelled it

    except:pass

    doItAll(resolution)

    # image names must be sorted, but are strings like '1.png', so dict is used

    beta_dirs=(os.listdir('/Users/milo/PycharmProjects/mandlebrot/venv/z_images/'+str(resolution)+'/'))

    dic={}

    for dir in beta_dirs:

        key=''

        for character in dir:

            if character in '1234567890-':

                key+=(character)

        dic[int(key)]=dir



    img = Image.new('1', (resolution*3, resolution*2))

    r_offset = 0

    for dir in sorted(dic.items()):

        im=Image.open('/Users/milo/PycharmProjects/mandlebrot/venv/z_images/'+str(resolution)+'/'+dir[1])

        img.paste(im, (r_offset, 0))

        r_offset += 100



    img.save(('z_images/brot' + str(resolution) + '.png'))

    print('saved as brot' + str(resolution) + '.png')

this is being run on a mac fyi, also it runs fine, just slow. mostly looking to speed it up, and allow for restarts more easily. I am running pool with more cores than I think I have, but activity monitor is showing best cpu utilization with 4 processes, so I don't know what I should do.
code produces B&W images of slices of the set, then concatinates them