Recompress Images...

[Puffolino]

...doesn't work as expected. When trying to compress selected images (one or more), I get the following result:

No changes were made. Please check your input data and try again.


Using the function "Recompress Image..." for a single image (instead of "Recompress Images...") everything works as expected.


BTW maybe some complex functions would show an optional summary information when finished, like "17 images compressed, 300KB -> 200 KB (66%)". There could be a checkmark in such dialogs nearby the "Ok" button which let the user decide if he wants to see an information or not...

[Sasha - Tracker Dev Team]

Hello Puffolino,

Thanks for the report.
Please confirm that you did not check the "Replace when size of new image is smaller..." checkbox. If it was checked then if the resulting size became greater after the recompression, then this image should be skipped. If this happened to all of the images, then the behavior is expected.

Cheers,
Alex

[David.P]

Hello all,

I was going to confirm that Recompress Images also does not work for me in certain cases (which I have yet to reproduce).

When it happens, I also get the message "No changes were made. Please check your input data and try again".

Also, the compression quality with JPEG2000 seems to be way too high in all quality settings of JPEG2000.

Even with the quality set to "Minimum", the JPEG2000 image file sizes are usually much higher than when using JPEG compression, for example. Also, even with the quality set to "Minimum", the image quality degradation with JPEG2000 is barely visible, in total contrast to JPEG, where compression artifacts are very noticeable at the "Minimum" quality setting. With the JPEG2000 quality set to "Maximum", the JPEG2000 image file sizes can be even higher than when using ZIP (i.e. lossless) compression, at least on certain images like renderings.

It feels as if the JPEG2000 "Minimum" quality setting compresses images still with about 90% quality instead of with around 15% (which I believe the JPEG "Minimum" quality setting uses to save images).

Here is an example. A JPEG image that had been created by recompressing a PNG (ZIP) image to JPEG with medium quality is now recompressed again to JPEG2000 with minimum quality, resulting in the image size almost doubling. Expected result: the JPEG2000-minimum image should have a much smaller memory footprint than the JPEG-medium image.



It would be great if the Devs could have a look at the JPEG2000 quality settings and distribute the percentages between "Minimum" and "Maximum" quality to a broader range somewhere between 10% and 95% image quality.

This way, files with lots of color images could be compressed more effectively, using the better compression that JPEG2000 offers over JPEG.

Thank you & best regards
David

[Tracker Supp-Stefan]

Hello David.P,

Thanks for this post! I've checked wtih our dev team and they asked me to create a ticket for this:
#6317: FR: Adjust J2K compression levels constants.

Kind regards,
Stefan

[chrisjj]

I add my vote for this fix.

[Arnold]

+1

[Jordan - Tracker Supp]

Hi Arnold and all,

We've just requested an update on the above ticket.
Will post again here when there are any updates.

[Tracker Supp-Stefan]

Hello all,

We've just had the ticket resolved with this comment:
"The Low level is reduced to what was before the Minimum Level.
The Minimum level is brought down to a significant deterioration in quality, but the size is reduced by 3-4 times from the previous Minimum level."

Kind regards,
Stefan

[chrisjj]

Thanks. Please pass on my suggestion that a clear warning be included with the release, making clear that the update can cause unchanged stored user settings to deliver a much reduced image quality.

[Tracker Supp-Stefan]

Hello chrisjj,

This change would have an effect only on new files that you will recompress - so the result would be immediately obvious, and you can then adjust your settings accordingly. I will check with the devs if the have already included a warning!

Kind regards,
Stefan

[chrisjj]

This change would have an effect only on new files that you will recompress

Obviously.

- so the result would be immediately obvious

Obviously not - since you'd have to check possibly hundreds of images by eye.

[TrackerSupp-Daniel]

Hello, chrisjj

We spoke with the dev team on this, and while it is not likely a warning will be added, they are looking into changing the way this option works to avoid the "low-medium-high" value confusion, by displaying an actual numerical "quality" value (likely by percentage). I cannot promise that this is definitely coming, but it is something they are looking into.

Kind regards,

[David.P]

Hello all,

...[Recompress Images] doesn't work as expected. When trying to compress selected images (one or more), I get the following result:

No changes were made. Please check your input data and try again.

Using the function "Recompress Image..." for a single image (instead of "Recompress Images...") everything works as expected

I was just going to note that this is not resolved yet. The issue is still present as described above by Puffolino.

In other words, most of the time when recompressing more than just one image, for example when recompressing the images of an entire document, the message mentioned above by Puffolino appears erroneously, and no changes are made to the document.

Strangely, sometimes it works when only a subset of all pages of a document is selected and then image recompression is applied to the selected pages. However, if most or all pages of the document are selected, or image recompression is applied to the entire document, most of the time it doesn't work, as noted above by Puffolino.

Hopefully this can be looked into and subsequently be fixed.

Best regards,
David

[TrackerSupp-Daniel]

Hello, David.P

I was under the impression this had been resolved already, Could I ask for a sample file to test with in the current build, as none of my current test documents seem to encounter any problems like this.
It would also help to see the exact settings being used for the recompression.

Kind regards,

[David.P]

Hello Daniel,

thank you for your reply.

I will make sure to provide a document and the exact recompression settings where this issue still happens.

Best regards,
David

[Tracker Supp-Stefan]