Newspaper halftone?

[Dick Margulis]

What's the trick to getting a sharp reproduction of a newspaper halftone
instead of a muddy, dithered, moire mess?

I scanned at 1200 dpi as a grayscale TIFF and again as a BMP. They look
great in Photoshop--nice, clean black dots with white between them and
vice versa. But after I place either of them in ID and output a
PDF/X-4:2008, they look like crap. What critical step am I forgetting?

Thanks,

Dick

[David Bergsland]

I’d guess downsampling or Output intent profile…

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[John Kramer]

And how are they being printed?
If offset, that will add yet another moiré possibility.

If you have a good clear scan, you might try converting to a Photoshop bitmap file with the 50% threshold setting. That should at least eliminate further half toning.

[Dick Margulis]

On 10/20/2015 4:25 PM, David Bergsland wrote:
> I’d guess downsampling

Thanks!

That was the clue that led me to the solution, which was in the way I
did the scanning. I don't do these often enough to remember automatically.

[Michael Brady]

Dick

> What's the trick to getting a sharp reproduction of a newspaper halftone instead of a muddy, dithered, moire mess?
>
> I scanned at 1200 dpi as a grayscale TIFF and again as a BMP. They look great in Photoshop--nice, clean black dots with white between them and vice versa. But after I place either of them in ID and output a PDF/X-4:2008, they look like crap. What critical step am I forgetting?

Several factors are at work here:

1. The screen resolution of your monitor is interacting with the original halftone dots; does the interference pattern get better or words when you enlarge the PDF on-screen?

2. Using grayscale mode will increase the likelihood of interference artifacts, regardless of the fact that the dots are nominally black and the paper white, because there will be some amount of antialiasing at the edges of the dots. That may have an effect here.

3. A grayscale will be halftoned when printed; a black-and-white image will not. Consider changing the gs image to b&w; increase the scanning resolution if needed, or if you use the original image at a reduced size, then the effective resolution of the b&w image may be enough. Printing film and plates used to be 2450 dpi. That should hold the dots in a b&w image pretty well.


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Michael Brady

[Dick Margulis]

On 10/20/2015 5:02 PM, Michael Brady wrote:
> 3. A grayscale will be halftoned when printed; a black-and-white image
> will not. Consider changing the gs image to b&w

That's what I was not able to do directly in Photoshop for some reason.
However, by going back to the scanner and scanning it as b&w with a 50%
threshold, I got what I wanted.

[David Blatner]

Here's a solution I wrote up some years ago that is usually far better than just scanning line art or halftones with a threshold:

https://indesignsecrets.com/scanning-line-art-for-use-in-indesign.php

Hope that helps!

--david blatner

[David Creamer]

Dick Margulis <di...@dmargulis.com>: Oct 20 04:19PM -0400

>What's the trick to getting a sharp reproduction of a newspaper halftone

>instead of a muddy, dithered, moire mess?

 

 

It has been a while, but I used to scan the image as high-res as my scanner allowed at its native resolution.

For example:

4800 spi (aka ppi or dpi)

100%

Grayscale

Place image on scanner bed at 15 degree angle.

 

In Photoshop…

                Zoom in so you can see the dots

                Gaussian Blur the image until the dots blend together

                Change the Image Size to normal resolution requirements and desired size

                Save as grayscale, LZW-compressed TIFF

 

Dave Creamer

IDEAS Training

[Dick Margulis]

On 10/20/2015 6:55 PM, David Creamer wrote:
> Gaussian Blur the image until the dots blend together

I was aiming for the opposite result--sharply visible 85 lpi dots
rendered as line work. But yes, for smoothing it out to a
continuous-tone image, Gaussian blur is the way to go.

[David Creamer]

Of course, the blurring only works if scanned at _very_ high res, blur, and then resample.

Dave Creamer