JPEG Optimizer and Image Artifacts?

[Jack Harvey]

I have a question about the JPEG Optimizer.  When I save a PixInsight processed image in JPEG with the Optimizer box checked my astro partners that review the image with PS note some artifacts that they complain about when the images are really blown up to 400-600 or so.  I found if I uncheck the optimizer I do not get the complaints.   I think we discussed this briefly a year or two ago but I forgot the answer.  Also wonder if anyone else has seen this?

Finally any chance a future version might have the option to open the JPEG window with the Optimizer not checked by default?

[Juan Conejero]

Jack,

This is very strange, because JPEG optimization doesn't affect image quality. It just improves compression in a small amount, so optimized files are usually smaller. Do you see those artifacts in PixInsight?

I would like to see an example of those artifacts. If you can write the same image they are complaining about, with and without optimization, we'll be able to evaluate them to see if there are significant differences. Use the same JPEG quality in both cases.

PixInsight uses the reference library created by the Joint Photographic Experts Group (JPEG), JFIF 1.02 Specification. As far as I know, there is nothing better to manage the JPEG format. Adobe Photoshop uses the same reference library, by the way.

You can disable optimization permanently on the JPEG Preferences dialog, available on the Format Explorer window. Just double click the JPEG format on the left panel.