This is the sixth installment of Paper to Pixel to Paper Again, a series that explains (in an overly thorough manner) the how-to's of preparing artwork of all stripes for print.

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If you haven't done so yet, please go back and read the previous installments.

Okay! Here's the drill! I'm going to present many techniques for cleaning images in this section , with an emphasis on the type of techniques that might apply to line art originals. We'll talk about a few of these techniques in greater detail when we get into newsprint originals in a layer installment.

There are MANY WAYS to do these things, many of which, I'm sure, I don't know! So any and all feedback about this, things I missed etc, is welcome in the YouTube comments.

Without further ado...

When writing the first draft of this back in 2017, I was in the midst of working on Jaka's Story, one of my favorite Cerebus books— not only because of the gorgeous, stylish art, but because of the pacing, which starts relaxed and leisurely, taking its time with the intertwining relationships of the characters, before accelerating to disaster. Here's a leisurely double-page spread, later redrawn with a tweaked viewpoint for the cover of the volume.

Our goal is to eliminate anything that we don't want to reproduce in the final book—any noise, ink splotch, extra corner doodling, whatever—while preserving all of the things that we might lose without this additional step—watery lines, super duper fine lines, etc.

Even at this zoomed-out vantage point we can see a few items that need eliminating, mainly, the "Issue__ Page__" chop at the upper left of the page, that were indicators to the printer of page order for the monthly volumes. We'll take care of this and any other noise in the margins with one easy to use method:

Cleaning method A: Selection and Fill

Hit M to bring up the Marquee Selection tool, which allows you to select rectangular units in your image. I quickly use this tool to select the outer parts of the image that are intended to be white, and, since there are big chunks of white space inside the image as well, I select these too. I see that the cut line on the top and bottom of the text paste-up is also visible, so I make sure my selection also overlaps these areas.

Here's my selection (notice the "marching ants," indicating the area that's selected).

Now I'm going to hit G to bring up the paintbucket tool. I've selected White from my color swatches, and, making sure my Cleanup layer is selected, I click in my selection, which dumps white into the entire selected area, essentially masking any noise or grit in these areas.

Here's what my cleanup layer now looks like, sans image layers.

Now hit CTRL-D, which De-selects.

Now we're going to take care of something that I already know is a chronic problem with these pages. Although it looks hand-drawn, the border of this image was actually made with Letratape, a type of border tape consisting of a black border and a clear sticky carrier backing, used for paste-up layouts. Over time, the edge of that sticky carrier has accumulated dust and debris, and we need to clean that edge in order for it to not reproduce (even if it ends up not being very noticable).

If we left this alone, it would cause a little stippled line on the edge of the carrier film to be visible in the printed book.

Fortunately, there's an easy way to take care of this, or any other similar noise problem. (I only wish I figured it out earlier!)

Cleaning Method B: Select and Median Noise Filter

Hit M to select the Marquee tool again, and select your Sharpened layer from the layers panel.

Now use the Marquee tool to select the border tape and border tape schmutz, careful to not overlap any lines with your selection.

Now zoom in on an area of the noise, and then go to Filter -> Noise -> Median.

This is one of those incredibly simple filters that are so basic they tend to get overlooked for filters with more bells and whistles. All the Median filter does is look for and apply an average of neighboring pixels to any selection, at a user-determined radius. In this case, any radius between 4 and 6 pixels completely eliminates my specs of debris without affecting my border tape at all. If the radius is too low, it doesn't get the big specks of dirt. If the radius is too high, it starts to soften the edge of my border tape.

Well, that was quick! We're about a minute into our cleanup and we've done most of what we need to do to this page (mostly because there's no mechanical tone on this page! The real time-suck on this project).

But before we move on from using our Median filter, we're going to check out one other area. From previous pages, I know that the big chunk of text on the right-hand side of the page was either photocopied or printed on a laser printer, and thus might have noise problems as well.

And so it does. We'll try the same solution as previous, bring up the Median filter and seeing if there's a radius that will knock out all of our noise without affecting our letter forms at all.

Oh, hey, a 4 px radius did the trick.

Now we're going to scan the page with our eyes, turning the Threshold adjustment layer on and off, looking for any areas of the page that have watery lines or super fine lines that might break up when Threshold is on. And in the lower left-hand corner, I find what I'm looking for. The lines indicating the snow are blowing out when the Threshold adjustment layer is on, and, at least after our adjustment, they look pretty gray compared to their neighbors.

(If this were a systematic problem with many or all pages, and the originals didn't also look that gray, then we might have a problem with our script. But my script seems otherwise fine, so I'm going to assume this is just the way it appears in the original art)

Here's the area in question:

There are a bunch (a bunch!) of ways to deal with this, but since it's mostly affecting one area of our drawing, let's try...

Cleaning Method C: Selection and Levels Command

I'm going to hit L to bring up the Lasso tool, which enables you to freehand a selection. Then I'll select the area, and make sure that my Sharpened layer is selected in my layers menu. Then I'll hit CTRL-L to bring up my Levels command:

And here we have our almost-instant fix. I've raised the black point just a bit, and moved the Mid Point (i.e. the gamma control) far to the right, watching the lines become blacker as it moves. Then I move around the White point to make sure there's no additional filling-in happening, only the gray lines becoming jet black.

In the days of manual darkroom development, this would have been a cumbersome process of masking off the area and overexposing it to get the desired fill-in. If the exposure were too long, the area would become clunky and clogged, the fine details in the hatching filling-in along with the lines. But now, it's a whole lot easier, at least if you happen to know how to do it.

So far all the work we've done as been with none of what you might think of as the "traditional" Photoshop cleanup tools. We'll get to why in a bit.

Let's take a look at another page from Jaka's Story.

This far zoomed out, the page is looking pretty good, with only a few visible problem areas. But really good commercial line art printing has a much higher effective resolution than even the best monitors around, so zooming in "waaaay too close" is important.

First I take care of making the white outer mask for the page with the marquee selection tool and the Paint Bucket, as discussed last week, and then use the Median noise filter on the edge of the panel border, also as discussed. Now I'm going to take a look at that first panel a little tighter in.

You can see we've got the "panel border shmutz" problem happening here pretty severely. Some of this might be caused by the sticky edge of the carrier film for the border "catching" schmutz over time. But some of it also looks like stray ink lines that were incompletely scraped off the border tape. You can also see an area (to the left and right of the Jaka figure here) that weren't scraped off at all). Regardless of the why, if we let this go as-is, it's going to mar the beautiful clean white border that's the intended look here. So clearly we're ready for another technique!

Oh! Hey! How about —

Cleanup Method D: Dodge Tool

Go ahead and select your Sharpen layer, i.e. the layer that represents your actual sharpened, visible artwork. And then select the Dodge tool (or hit O. Learn your shortcuts!)

In the upper tool preferences bar, change the "Range" to Highlights and the "Exposure" to 100 percent. This is now our "schmutz on white" tool, the perfect way to brush an area to eliminate black on white schmutz on a page.

Very important: DO NOT use this tool over an area of dot tone or mechanical hatching! Even if the effect is not visible to you on screen, it WILL be visible in print. Your eye "reads" dot tone as a continuous gray tone, and thus any changes made to it, however slight, are visible in print when it's resolving to your eye.

With the above caveat in mind, why use this tool? Well, because it's only effecting the highlights of an area, you can sweep over the edge of, say, that cross-hatching, and not have to be as precise as you would be with a brush.

So with a little bit of work with the Dodge tool, I've eliminated a lot of the border schmutz, but there's still some work to do. I think it's time, finally to switch to the tool I've been avoiding.

Cleanup Method E: the Brush tool

Yes, the humble Brush tool (hit B for the shortcut). It's the most basic cleanup method available to you. For our purposes, we want pretty specific settings:

Round brush--no fancy pants shapes or blending modes etc.

100 Percent opacity

Hardness at 100 percent

Size controlled by pressure of pen on tablet (buy a tablet!)

Color at either 100 percent black or 100 percent white (X shifts between them)

Size-- As big a brush as you can get away with using (hold [ or ] to change brush size)

Select your Cleanup layer, and then go to town!

So, why have I avoided talking about this so far?

It's simple—I think that the less cleanup you do with the Brush tool, the more efficient you'll work.

It feels good to fill something in all the way black. It feels good to get all of the little dots of noise out of the white. Satisfying, like you're really ACCOMPLISHING something.

But, more often than not, those same things can be accomplished more efficiently with one of the other tools I've discussed so far.

Moreover, you don't actually need to eliminate every speck of white from your black areas! The real problems you need to look for are systemic ones—an entire area of your page with broken up black. The white lines unintentionally in the black, like you see above. Noise that is in a particular shape, or, say, cut lines around an object that was pasted on. Those are the kinds of things that will likely be visible in print, not that little grain of white that will soon be swallowed by the black ink surrounding it.

Lastly, make sure to click your Threshold adjustment layer on and off as you work, to preview what your image will look like as a bitmap. Often times things that you think might be problems will disappear completely after the Threshold adjustment.

(We'll return to all of these issues in greater detail when discussing restoring comics from newsprint...)