Flip jp2 data vertically before saving

[dgarciabriseno]

PR Description

Fixes #7485

Flipping the data array when saving as jp2 fixes this problem.

[dgarciabriseno]

[ayshih]

You need to fix the relevant unit test (

sunpy/sunpy/io/tests/test_jp2.py

Lines 44 to 46 in f79e5d9

	# Sanity check that reading back the jp2 returns coherent data
	jp2_readback = _jp2.read(outfile)
	assert header['DATE'] == jp2_readback[0].header['DATE']

) so that it actually verifies the output

[ayshih]

Add a comment that explains that we have to flip the array back here because we flip it upon reading (due to the difference in the origin of the data)

[dgarciabriseno]

Will do.

[dgarciabriseno]

Where does it get flipped when its read in?
Oh it's the [::-1]

[dgarciabriseno]

I added a comment here, and updated the test to verify the data array after reading it back.

[dgarciabriseno]

You need to fix the relevant unit test (

sunpy/sunpy/io/tests/test_jp2.py

Lines 44 to 46 in f79e5d9

	# Sanity check that reading back the jp2 returns coherent data
	jp2_readback = _jp2.read(outfile)
	assert header['DATE'] == jp2_readback[0].header['DATE']

) so that it actually verifies the output

How would you recommend doing that?
I'm not sure the result will match the original fits data array since it casts the data to uint8 to save it as a jp2. (There's other issues with doing that too, a simple cast isn't sufficient to convert from fits to jp2).

edit:

• I suppose I could cast the original data to the uint8 array and then compare it.

[wtbarnes]

Just needs a changelog, but other than that looks good to me.

Fixed now hopefully

[lumberbot-app]

Owee, I'm MrMeeseeks, Look at me.

There seem to be a conflict, please backport manually. Here are approximate instructions:

1. Checkout backport branch and update it.

git checkout 5.0
git pull

2. Cherry pick the first parent branch of the this PR on top of the older branch:

git cherry-pick -x -m1 76c3cedb9da116309eae5813db6d8987552c8317

3. You will likely have some merge/cherry-pick conflict here, fix them and commit:

git commit -am 'Backport PR #7486: Flip jp2 data vertically before saving'

4. Push to a named branch:

git push YOURFORK 5.0:auto-backport-of-pr-7486-on-5.0

5. Create a PR against branch 5.0, I would have named this PR:

"Backport PR #7486 on branch 5.0 (Flip jp2 data vertically before saving)"

And apply the correct labels and milestones.

Congratulations — you did some good work! Hopefully your backport PR will be tested by the continuous integration and merged soon!

Remember to remove the Still Needs Manual Backport label once the PR gets merged.

If these instructions are inaccurate, feel free to suggest an improvement.