Monday, March 30, 2009

Cleaning up stray pixels in Photoshop

This is scanned artwork with the contrast exaggerated to make it easier to see the problem of stray pixels caused by paper texture, dust, etc.
How do you deal with this problem, especially when it’s hard to see where the pesky little unwanted pixels are? Usually when I'm working on an image in Photoshop, the stray pixels are less obvious, more like the image below:
What’s the big deal, anyway... who cares about a few stray pixels? In some cases they won’t matter, but when your image will be used as an illustration it’s amazing how often they turn into glaring blotches in the printed piece that really are bothersome. To find and eliminate them, read on.

This is line work that has been scanned in and lifted off the background white paper. This post explains how to do that.

I zoomed in to erase any visible pixels. But are there more lurking? To find out, add the Stroke Layer style to the lines layer. In the top menu bar, choose Layer>LayerStyle>Stroke. When the dialog box opens, use these settings (most are default):
Size- 3 to 5 pixels
Position- Outside
Blend Mode- Normal
Opacity- 100%
Fill type- Color (pick a bright contrasting color such as red)

Either the drawing suddenly contracted chicken pox, or the red stroke around every pixel shows that there are indeed many stray pixels. Select them with the Lasso tool and delete or use the Eraser tool to remove them.

These car images can be enlarged by clicking on them, by the way.

I don’t worry too much about a few blips near the line work, since they will blend in. It’s the glitches floating inches away that seem to show up most annoyingly in the printed book. Now that the art is cleaned up, time to finish coloring it in. Don’t forget to get rid of the Strokes Layer style. The easiest way is in the Layers palette, drag the Effects to the trash, the small icon on the lower right.

Here’s our little car, ready for his close-up. Wonder why he’s got a sail on top?


June said...

Thanks for this tip, I hadn't ever thought of using a Strokes Layer to emphasise the strays.

Loreen Leedy said...

Me either until I did some digging around online. I had been experimenting with putting the Lines layer in Dissolve mode. While it shows some stray pixels, it doesn't show all of them. Adding the Strokes layer style really does the trick!

Diane J. Evans said...

I have really been enjoying your series on Photoshop tips, Loreen -- I've printed out a few of the posts to help me navigate around the program. Thank you for sharing your expertise with all of us.


joyceshelton said...

Yep, that's my Photoshop Guru! Keep 'em coming! I don't know what I'd do without you!

Loreen Leedy said...

You're all very welcome. I've learned so much from other bloggers and am enjoying sharing what I've discovered, too.

BJ Lantz said...

Hi Loreen ~ I've heard so many nice things about you from our mutual friend Joyce Shelton! I followed a link from her blog today to find your lovely blog. I love, love Photoshop tips and this is a good one. Thanks for that! You might find use from one I posted a few weeks ago: