Say I have an image of size 3841 x 7195 pixels. I would like to save the contents of the figure to disk, resulting in an image of the exact size I specify in pixels.

No axis, no titles. Just the image. I don't personally care about DPIs, as I only want to specify the size the image takes in the screen in disk in pixels.

I have read other threads, and they all seem to do conversions to inches and then specify the dimensions of the figure in inches and adjust dpi's in some way. I would like to avoid dealing with the potential loss of accuracy that could result from pixel-to-inches conversions.

I have tried with:

w = 7195
h = 3841
fig = plt.figure(frameon=False)
fig.set_size_inches(w,h)
ax = plt.Axes(fig, [0., 0., 1., 1.])
ax.set_axis_off()
fig.add_axes(ax)
ax.imshow(im_np, aspect='normal')
fig.savefig(some_path, dpi=1)

with no luck (Python complains that width and height must each be below 32768 (?))

From everything I have seen, matplotlib requires the figure size to be specified in inches and dpi, but I am only interested in the pixels the figure takes in disk. How can I do this?

To clarify: I am looking for a way to do this with matplotlib, and not with other image-saving libraries.