John,
The blurring you see when running ArrayPlot on an iPad (via the Wolfram Cloud app or a browser) but not on an iMac is due to how the Wolfram Cloud renders the graphic for display on different screen resolutions and platforms.
The Fix: Forcing High Resolution
The solution is to force the Wolfram Language to render the image at a higher resolution before it is sent to the Cloud interface. You do this by setting the ImageResolution option within the ArrayPlot (or generally, the Show) function.
The standard resolution is 72 DPI. Try setting it significantly higher, for example, to 300 DPI, which is standard for printing and high-quality display:
ArrayPlot[CellularAutomaton[250, {{1}, 0}, 10], ImageResolution -> 300]
What this does:
The Cloud kernel generates a much larger, more detailed image on the server.
The iPad receives this high-resolution image.
When the iPad scales this image down or displays it natively, there are enough source pixels to maintain the sharp edges of the grid, eliminating the blurring effect caused by scaling a low-resolution graphic.
Version 1.5.8 Wolfram Cloud app released on Nov. 12, 2024
