plt.scatter(..., antialiased=False)
plt.plot(..., marker="o", antialiased=False)

import io
import matplotlib
matplotlib.use("TkAgg")
import matplotlib.pyplot as plt

fig, axes = plt.subplots(ncols=2, figsize=(.5,.25), dpi=72)
fig.subplots_adjust(0,0,1,1,0,0)

## Produce a line plot, a scatter and a circle
## Set antialiased=True, False to observe the difference.
for aa,ax in zip([True,False],axes):
    ax.axis([0,3,0,3])
    ax.axis("off")
    ax.plot([.8,1.2,1.8,2.2],[1,.6,.6,1], antialiased=aa)
    
    ax.scatter([2],[2],s=16,edgecolor="k",facecolor="C1", antialiased=aa)
    ax.plot([1],[2],marker="o",ms=4,mec="k",mfc="C1", antialiased=aa)
    c = plt.Circle((1.5,1.5), radius=0.35, edgecolor="k",
                   facecolor="C3", antialiased=aa)
    ax.add_patch(c)

buf = io.BytesIO()
fig.savefig(buf)
#fig.savefig("test"+str(matplotlib.get_backend())+".png")
plt.close()

## Read and show the produced images from above as imshow
fig, (ax,ax2) = plt.subplots(ncols=2, figsize=(5,2.6))
buf.seek(0)
im = plt.imread(buf)
ax.imshow(im[:,:im.shape[1]//2], origin="upper")
ax2.imshow(im[:,im.shape[1]//2:], origin="upper")
ax.set_title("antialiased=True")
ax2.set_title("antialiased=False")
fig.suptitle(matplotlib.get_backend())
fig.savefig("antialiased"+str(matplotlib.get_backend())+".png")
plt.show()