Hi Alan, thanks for the reply!
So would it be safe to assume that glow & drop shadow effects in InDesign are raster effects, not vector, since you are able to add noise to them in InDesign?? I was just hoping that since those effects could introduce noise, the option for a gradient (or probably gradient feather) might do the same, even if it rendered the element as rasterized.
But I did try the 50% grey Photoshop image with noise option. We could live with this since we’d still be able to create all the different gradients needed in InDesign without having to hop back to Photoshop all the time.
I figured out that the gradient needs to be applied to the FRAME, while the image is just colored black and given a blending mode (I’m trying Overlay as assuming that would be most neutral, not introducing anything but the noise). However, with this method I seem to get a hairline around the image frame that I can’t get rid of. It doesn’t have a stroke, the image is larger than frame, there are no effects, etc. But there is a definite hairline that I can see where the gradient is white (or very light). In overprint preview mode, I am able to actually detect ink in the black channel there, so I don’t think it’s a preview issue.
If I try the ‘gradient feather’ method, I don’t get the hairline. And from what I can tell (at least on screen), it displays as smoothly as the standard gradient method.
I had just read somewhere (can’t find it now) that the gradient tool creates a gradient in a technically different manner (with better results) than creating the same gradient using the ‘Gradient Feather’ method (e.g., with a solid fill). But I imagine that might be due to it not having any transparency (and therefore being rasterized) by default compared to the gradient feather (something about the way a good RIP can interpret it). But if I am using a blending effect with my grayscale TIF, then I guess that introduces transparency into the gradient when using method 1 above anyways.
And I believe we have noticed a difference with certain printers having less issues with gradients than others. So I’m sure with proper RIPs and techniques, it may be a non-issue. We just don’t always get to choose the printer and wanted a ‘better-safe-than-sorry’ workflow here without adding hours to development.