InDesign 2025 transparency and drop shadow issues

[philipb31687500]

iMac 2017, Ventura 13.7.6, InDesign 2025

Applying a small transparent caption frame over a full page greyscale image causes the whole image to lose contrast when transparency is applied.

Also when applying drop shadow to an item on a spread, greyscale images on that page and adjacent page also lose contrast. These images do not contact the drop shadow item in any way.

I cannot see any change to CMYK images.

Is this a bug - any advice please?

Phil in Welland, UK

[Eugene Tyson]

Check your transparency blend space in Edit>Transparency Blend Space

[Willi Adelberger]

Where do you check the change to CMYK images?

Do you mean from the greyscale image or another one?

[Abhishek Rao]

Hi @philipb31687500,

Thanks so much for sharing the details. I see that Eugene suggested checking your transparency blend space (under Edit > Transparency Blend Space), which is often the key reason for contrast changes in grayscale images when using transparency or drop shadows. Could you please try that and let us know if it helps?

Also, could you confirm the exact version of InDesign 2025 you're using, for example 20.4.1 or 20.4?

If possible, it would be really helpful if you could share a short screen recording showing the issue happening on your layout, so we can review it in detail.

Looking forward to your update!

Abhishek 

[philipb31687500]

Try again!

Thanks all for the replies.

Blend space is Document CMYK.

The greyscale images originate as scans supplied to me for printing and arrive already as greyscale, or sometimes as RGB. So in Photoshop Image>Mode>Greyscale.

InDesign is 20.4.1.

What I find difficult to understand is how a greyscale image can change when it is nowhere near where the transparency is being applied.

The suggestions made did cause me to make an experiment and change the greyscale to CMYK. And that seems to work. Don’t understand why!

Please see the short screen recording, with the image duplicated - one in CMYK and original in greyscale.



Many thanks again, and suggestions welcomed. Hope the movie works…smaller now.

Phil




[rob day]

What I find difficult to understand is how a greyscale image can change when it is nowhere near where the transparency is being applied.

Grayscale images display on the CMYK Black place when the Transparency Blend Space is CMYK, and Overprint Preview is turned on, or when there is any transparency on the spread. Most CMYK press profiles display 100% Black as something less than absolute black, which is what will happen on press. A rich black (black plus CMY percentages) will appear as a darker value on press.

See this thread:

https://community.adobe.com/t5/indesign-discussions/dot-gain-or-gray-gamma/td-p/8365606

[rob day]

Also, setting your Blend Space to RGB when printing to an offset press can cause problems on press—small black text that should print as black only will print as 4-color.