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pdqdesign
Participant
March 27, 2017
Question

Opacity issue on greyscale images

  • March 27, 2017
  • 2 replies
  • 1264 views

Hope you can help. There are 2 objects only on the InD page. A greyscale image and a rectangle box. When adjusting the opacity of the rectangle box/object, the greyscale image also changes opacity. We can however adjust the opacity on the greyscale image...and the rectangle box is not affected. But that's not what we want.

We're making an ad for a newspaper...so it needs to be greyscale (made up from black only).

1. We've placed a pixel-based greyscale (PS > image menu > mode > greyscale) TIF image on the InD page

2. Then placed a black rectangle beside it (InD > rectangle tool).

3. If the opacity is adjusted on the black rectangle (object menu > effects > transparency - normal blend mode), the greyscale image, also sitting on the page, is affected (becoming lighter/darker)

It's not just an onscreen drawing thing in InD because if a PDF is made from this, the image is still lighter - it doesn't have 100% opacity.

It only happens on greyscale images. If the image is CMYK (or RGB) they are not affected by adjusting a different obect's opacity.

We have tried different greyscale images. Restarted InDesign. Restarted machine. Is happening on 2 different computers both running same setup.

Specs: Mac OSX El Capitan, InDesign CC 2017.

Thank you for any help you may offer.

This topic has been closed for replies.

2 replies

rob day
Community Expert
rob dayCommunity Expert
Community Expert
March 27, 2017

It only happens on greyscale images. If the image is CMYK (or RGB) they are not affected by adjusting a different obect's opacity.

If there's no transparency on the page do you also get the change when you turn on Overprint Preview?

InDesign color manages grayscales differently depending whether you have OP turned on or off. With Overprint off the preview of grayscale objects is sGray (sRGB or 2.2 gamma), which is useful if you are designing for screens. With Overprint on, the preview shows how the grayscale is expected to print on the black plate, and your document's CMYK profile affects the preview. If the assigned profile is a newsprint profile the change would be more noticeable because of newsprint's lack of dynamic range. That simulation would carry over to Acrobat if you export with a PDF/X preset

If your Transparency Blend space is CMYK adding transparency also forces the newsprint CMYK preview.

Here my assigned profile is ISO Newspaper v4 26

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pdqdesignAuthor
Participant
March 27, 2017

Thank you Rob for your reply and explanation.

No it doesn't happen if Overprint Preview (view menu > overprint preview) is selected. As soon as Overprint Preview is turned on, the greyscale image immediately drops in contrast - it looks lighter/fainter on screen.

rob day
Community Expert
rob dayCommunity Expert
Community Expert
March 27, 2017

No it doesn't happen if Overprint Preview (view menu > overprint preview) is selected.

As soon as Overprint Preview is turned on, the greyscale image immediately drops in contrast - it looks lighter/fainter on screen.

You mean yes it happens (the contrast change) with Overprint Turned on?

Only the appearance on screen (and output as PDF or printing to office printer) changes.

You can check the actual output values via InDesign's Separation Preview's separation numbers, or AcrobatPro's Output Preview. You shouldn't be seeing placed grayscale output values changing in either app.

Willi Adelberger
Community Expert
Willi AdelbergerCommunity Expert
Community Expert
March 27, 2017

Do the values change or only the appearance on the screen. There are some known issues when transparency comes into the game that the screen preview in InDesign changes.

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pdqdesignAuthor
Participant
March 27, 2017

Only the appearance on screen (and output as PDF or printing to office printer) changes. The opacity values for the greyscale image remain at 100%.

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