Make Linked images have inverted colours

[DesignSurge]

While doing a bit of experimenting I came across what may be a bug.

• I opened a CMYK PDF in Publisher (original artwork created with InDesign)
• From the 'Resource Manager' dialogue I selected the images and chose 'Make Linked'
• Images saved as .jpg into a folder
• File saved as a Publisher document

The process seems to be working well except that the images that are now linked and saved into the folder have inverted colours - ie. have become negative.

[Old Bruce]

How are you doing the third item: "Images saved as .jpg into a folder"? I have seen this sort of thing before with conversions in other software over the years it is because CMYK is subtractive so the CMYK channels are negatives. And JPEG isn't CMYK so it is reading the C as Red and the M as Green and the Y as Blue and disregarding the K (black).

 

Edit: Just a thought Are you just changing the file extension? *.PDF to *.JPEG

[thomaso]

5 minutes ago, Old Bruce said:

And JPEG isn't CMYK

Hm?  – I assume this to be a rendering issue in what program ever.  https://support.apple.com/de-de/TS1252 

Just as test I place a cmyk.jpg to see what happens in my and your browser:

 

 

[fde101]

56 minutes ago, Old Bruce said:

JPEG isn't CMYK

JPEG does support CMYK but it is used so rarely in the "normal" world that many applications don't support it correctly if at all.

[DesignSurge]

I can see that my original post isn't very clear, so I will add a bit more detail.

The idea is that I am testing out how viable it is to convert PDF's into AP files and save the images as linked instead of embedded.

I have tested this out with two PDF's generated from InDesign files. One PDF contains CMYK .tif photos and saved as PDF/X-1a, the other contains CMYK photoshop .eps photos and saved as a 'press quality' non flattened PDF.

When opened in AP and according to Resource Manager, the images are all CMYK .jpg - I assume this is because both PDF's use JPEG compression when being exported from InDesign, hence AP sees them as .jpg instead of the original format? I am not manually changing file extensions or anything like that.

Within AP Resource Manager I used the option to make embedded photos linked, which then prompts for a folder to save them in (as in point 3 above 'Images saved as .jpg into a folder').

At this point when images are saved they are also inverted.

So, now I have just done another quick experiment. I saved a PDF containing CMYK .tif images from InDesign but this time I made sure JPEG compression was turned OFF, when opened in AP the images are still .tif and when selecting 'make linked' they are saved into the folder without being changed to negative.

There is the bug - When using AP to open a CMYK PDF that uses JPEG compression and then changing images from embedded to linked, the .jpg images saved become negative.

 

 

[thomaso]

3 hours ago, DesignSurge said:

There is the bug - When using AP to open a CMYK PDF that uses JPEG compression and then changing images from embedded to linked, the .jpg images saved become negative.

Weird, indeed. But it might be worse that those images opened from a PDF have lost their color profile information, according to Resource Manager.
That way it might become more or less risky or useless to take such images for further use, regardless if used embedded or saved negatively.

[Wosven]

Interesting to know where the bug come from.

I already mentioned this and others bugs when opening some PDFs.

 

[Seneca]

4 hours ago, DesignSurge said:

When using AP to open a CMYK PDF that uses JPEG compression and then changing images from embedded to linked, the .jpg images saved become negative.

Just a wild shot. When you enable TIF compression are they compressed for Mac or Windows. I wonder would that make any difference.

[Jon P]

Thanks for reporting this, I've reproduced the issue with images becoming inverted when linked and the file is reloaded and have logged it.