Describe the bug
I'm trying to use the Marvin Image task locally but I cannot find where/how to download the images from so that Marvin can access them. I have tried downloading the images from the SDSS Legacy Imaging images (https://www.sdss.org/dr17/manga/manga-data/data-access/), but Marvin Image does not recognize them.

To Reproduce
I have the SDSS Legacy Image of plateifu='7443-12703' downloaded. I've tried these different ways of calling it:
im = Image(plateifu='7443-12703')
im = Image(plateifu='7443-12703', mode='local', data-origin='dir'), where dir is the name of the file
im = Image(plateifu='7443-12703', mode='local', data-origin='dir'), where dir is the name of the directory where I save the file
In all cases I get:
MarvinError: failed to retrieve data using input parameters.

Expected behaviour
I would like Marvin Image to plot an image with a pink hexagon around it (the default output of the Marvin Image task) for a set of plateifus. Given that I have thousands of galaxies, I would like this to run locally, so I would be very thankful if you could let me know which images to get so that Marvin Image works (the ones from the SDSS Legacy Imaging seem not to be recognized).

Screenshots
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Desktop (please complete the following information):

• OS: 10.13.6 High Sierra
• Version of Marvin: latest (2.7.0)

Additional context
Add any other context about the problem here.