Using Effects like Drop Shadow lightens photos on page?

[Niina37563549w64e]

I have a problem which I cannot understand. When I add an effect like drop shadow or innes glow to a text or photo frame, it makes all photos on the page lighter. Even if I add the effect only to text not photos at all, it makes photos lighter. This appeared today, not before. I updated ID after thatWhat is wrong? Am I doing something wrong or is this a bug in ID? My ID is version 19.4 and I used grayscale photos, if that matters.

[Eugene Tyson · Accepted solution]

Adding any effect adds 'transparency' to the page
https://creativepro.com/my-grayscale-images-and-colors-changed-suddenly/

[Niina37563549w64e]

Thank you, this is very informative. I just wondered why this happened because this was the first time this appeared, and I have been working with ID over a decade. 

[rob day]

You will get the same preview when there is no transparency by turning on Overprint/Separation Preview. Try placing a Grayscale image in a new doc with the Intent set to Print, and toggle OP in and off.

[rob day · Accepted solution]

Hi @Niina37563549w64e , Also, the David Blatner article Eugene links to suggests changing your document Transparency Blend Space to RGB. Keep in mind that if your output will be to an offset press, the Grayscales (and black text) will likely output as 4-color CMYK.

If you keep the Blend Space as CMYK, the grayscales will output or export unchanged on the CMYK black plate. With the blend space as CMYK or Overprint turned on, the document’s CMYK profile handles the preview of the black plate and grayscales, which is why the preview appears different. More on that here:

https://community.adobe.com/t5/indesign-discussions/greyscale-jpegs-or-psd-images-are-going-much-dar...

[Niina37563549w64e]

This layout I was making is for online publish only so I can simply use RGB. I try that, thank you very much! I was just conbfused ant thought that either my ID has abug or I have done something wrong because I had not met this problem before with any layout over a decade. Means that I must have been lucky not to bump into this before yesterday.