Rotate image - loss of quality, bigger size

[mrwul]

When I rotate an image, the size is by about 4x as large, i.e. a 1.25MB image increases to about 5.5MB
How come?

That aside, wonder how much the photos degrade in quality.
(jpg)

Oh, If this is done with PNG how would that work out - I have no way to test it, question is more out of curiosity.

Thanks
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later .. example

with these settings:
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SnagIt-13082013 112957.png (61.41 KiB) Viewed 519 times

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results:
no changes, only the file size

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SnagIt-13082013 112717.png (80.06 KiB) Viewed 519 times

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filesize from 1.3MB to 5.6MB

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[DOS386]

When I rotate an image, the size is by about 4x as large, i.e. a 1.25MB image increases to about 5.5MB

1. Used "ordinary rotate" and resaved, rather than lossless JPG rotate ?
2. JPG ?

> How come?

Expected effect. The new JPG was saved with a higher quality setting than the original (bad idea).

> That aside, wonder how much the photos degrade in quality. (jpg)

Expected effect. JPG is lossy. Resaving will always degrade quality, even if the new file is bigger.

> Oh, If this is done with PNG how would that work out

Lossless for 90 degree rotations.

> I have no way to test it

??? how did you manage to prohibit PNG's on your PC ???