What Photoshop filter to use?

by admin on March 18, 2009

We will now take a break from making our usual portentous announcements on state of the world and prepress in general to focus on a specific technical. One that I am having. With a client who dumped this on me (as clients do) before leaving for spring break. And I'm okay with that, as clients are supposed to leave you with challenging material, because if it wasn't challenging, they could do it themselves and then they wouldn't be clients. They would be competitors. Got that?

Anyhoooo, see the scan up above? Does it look faint to you? You should have see it before I applied the "unsharp mask" filter to it in Photoshop. Unfortunately, I have seven other scans just like the one above, and with some of them, the unsharp mask filter doesn't have much of an effect. Thus, I throw myself upon the collective wisdom of my daily readership, which surprisingly has hit triple digits or so Google Analytics tells me.

I doubt I am the first people in all of creation to be confounded with light scans of drafting schematics. What filter would you use to thicken lines in the image above?

Update March 20th. Hey, thanks for the answers. I used Gassian blur followed by threshold at about 230-240 and it worked like a charm. I'll try to post screen caps later about that.


Allan Larson March 18, 2009 at 1:08 pm

Posterize down to about 3 levels. Or, select levels and grab white point in background and black point on the linework.

I wouldn’t unsharp mask it, but in a pinch you could Trap within Photoshop but this could lead to a multitude of sins.

Streamline it and redraw it DJ. Come on. Old School.

Dave VH March 19, 2009 at 3:27 am

A method I have used on my clients “challenging material” is to apply a slight Gaussian blur, essentially thickening the type and lines (or fuzz in this instance). Then in levels bring the black value way up, somewhere north of 200 (210ish tends to work for me) and drop the whites a bit till your line weight looks good, then convert to bitmap using 50% threshold. Let me know if it works for you.

Dan Curry March 19, 2009 at 5:50 am

Assuming the scan is in Grayscale mode, I would use Threshold to fatten up the lines. If there is not enough gray tonal range to do that, I would add a tiny bit of Gaussian Blur first (to introduce the grays) and then mess with Threshold.

admin March 19, 2009 at 7:49 am

Thanks for the help guys, I’m going to work on the drawings tonight and let you know how it works. But today we have 8 kids in the house (spring break)

Bob January 10, 2012 at 1:42 pm

similar problem. Have a lot of magazine scans with bleed through, by using “enhance>lighting>levels” you can drag the white pointer back to the knee of the curve to get rid of it but it also gets rid of a lot of the text fat. I’ve found that it’s better to next apply Gaussian blur and then move the black point with “levels” up to about 150 or whatever looks right. If I do the same process but use “threshhold” instead I lose parts of the text/lines.
You’d think that the two would be the same but they are obviously not.

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