I want to display an image (say 800x800) with Matplotlib.pyplot imshow() function but I want to display it so that one pixel of the image occupies one pixel on the screen (zoom factor = 1, no shrink, no stretch).
I'm a beginner, so do you know how to proceed?
Matplotlib isn't optimized for this. You'd be a bit better off with simpler options if you just want to display an image at one-pixel-to-one-pixel. (Have a look at Tkinter, for example.)
That having been said:
import matplotlib.pyplot as plt import numpy as np # DPI, here, has _nothing_ to do with your screen's DPI. dpi = 80.0 xpixels, ypixels = 800, 800 fig = plt.figure(figsize=(ypixels/dpi, xpixels/dpi), dpi=dpi) fig.figimage(np.random.random((xpixels, ypixels))) plt.show() Or, if you really want to use imshow, you'll need to be a bit more verbose. However, this has the advantage of allowing you to zoom in, etc if desired.
import matplotlib.pyplot as plt import numpy as np dpi = 80 margin = 0.05 # (5% of the width/height of the figure...) xpixels, ypixels = 800, 800 # Make a figure big enough to accomodate an axis of xpixels by ypixels # as well as the ticklabels, etc... figsize = (1 + margin) * ypixels / dpi, (1 + margin) * xpixels / dpi fig = plt.figure(figsize=figsize, dpi=dpi) # Make the axis the right size... ax = fig.add_axes([margin, margin, 1 - 2*margin, 1 - 2*margin]) ax.imshow(np.random.random((xpixels, ypixels)), interpolation='none') plt.show() If you don't really need matlibplot, here is the best way for me
import PIL.Image from io import BytesIO import IPython.display import numpy as np def showbytes(a): IPython.display.display(IPython.display.Image(data=a)) def showarray(a, fmt='png'): a = np.uint8(a) f = BytesIO() PIL.Image.fromarray(a).save(f, fmt) IPython.display.display(IPython.display.Image(data=f.getvalue())) use showbytes() for show a image bytes string, and showarray() for show a numpy array.