Safe to Use Images with White backgrounds?

[michaelsgoldman]

For digital illustrations with transparent backgrounds. Is it better to flatten with white backgrounds before coverting to grayscale and placing in InDesign or leaving the backgrounds transparent? Transparency is not needed in InDesign (no overlapping elements). And transparency is causing unexpected results converting to Black Ink CMYK profile.

I was lead to believe that white rectangles could create artifacts during printing. Is that not true?

[Mike Witherell]

A lot depends on your color management settings. Can you describe them?

[michaelsgoldman]

I am converting digital pencil illustrations in sRGB to working gray profile set to Black Ink - PSO Uncoated ISO12647_eci. Monitor is hardware calibrated. Illustrations are placed into InDesign as PSD files, text is wrapped around illustrations, so if I included "white" backgrounds for illustrations it would be behind text. Exporting to printer PDF/X1-A specs (all transparency flattened high res) for web offset printing on uncoated natural stock. No color conversion or tagged color profiles on export per their requirements since all images are already in the correct color profile in InDesign file.

Is a white rectangular background going to just be ignored on print or can it cause issues?

[rob day]

Exporting to printer PDF/X1-A specs (all transparency flattened high res) for web offset printing on uncoated natural stock.

Hi @michaelsgoldman , If you are exporting to the default PDF/X-1a preset, all transparency gets flattened on export and the grayscale's values export unchanged to the Black plate. Doesn't matter if the flattening happens in Photoshop or on Export the output values will be the same.

[Mike Witherell]

In addition to that, tho, can you tell about these other global settings?

1. What color management did you setup and synchronize from Photoshop > Edit > Color Settings (and ID > Edit > Color Settings)

2. What is the color model of the InDesign file under Edit > Transparency Blend Space?

[michaelsgoldman]

Working RGB = sRGB and Working CMYK = PSO Uncoated ISO12647_eci for both Photoshop and Indesign. InDesign transparency blend space set to CMYK.

[rob day · Accepted solution]

Also, make sure you turn on Overprint/Separation Preview, turning it off can affect the preview of transparency.

Here my [Paper] Swatch is not absolute white. The bottom image was flattened in Photoshop, the top image has a transparent background:

With Overprint/Separation preview turned on I get a preview of the output’s flattened transparency—images with and without transparency preview the same.

[michaelsgoldman]

Ok awesome, I see that it should output fine. Can't remember where I originally heard that white edges can create artifacts during printing, but then google's AI summary repeated it, so I was not sure.