how to open .png files

As a test, create a new user on your mac and see if Preview can open the png files when running in the new account.

Also you may want to try opening them in your own account whilst running in Safe Mode. Let us know.

If either of those two (or both) work correctly it will suggest an issue with your account, possibly third party software that is causing a conflict.

Open them in another graphics app until you figure out why preview is not working for you.

you can try a free viewer like Xee, seashore or pinta and see if they can display it

if all share the same issue with all png files around then I would worry

Can you open any .png files?

For example from here? Google Image Search

Hi,

Preview, Safari can handle png files.

So what happens when you download the png image of the dice on the page I linked to?

Interesting. Does the same thing happen if you use FireFox to download the image?

This is a bit concerning, especially the part about Safe Mode.

Just in case, it does not hurt to try resetting the NVRAM and SMC.

Also, try running Etrecheck and post its report here.

Hi again. It's possible Blackboard is corrupting the files somehow but without access to the files there's no way to check.

tiffanymyers23 wrote:

It's supposed to be a screenshot of a worksheet; however, this pixilated image is what comes up after I download the file on Safari and click on the download arrow (Black circle, with white error) to open the image.

Can you see the image correctly while it's open in Safari? How are they sending you the png's?

png files are images/pictures/graphics. Open then in any app that opens images.

https://en.wikipedia.org/wiki/Portable_Network_Graphics

The screen shot you posted looks like it is Preview. I'm not sure what others are seeing.