Got tiny random speckles or dots or spots, on the white background of comics pencils or inks? Want to easily remove these in Photoshop?
THE PROBLEM: One of the problems with scanned pencil or ink line art, and also sometimes with Poser’s old-style ‘toon outlines’ in the Firefly renderer output, is the tiny speckles found on the white background. The closer your Poser camera gets to a character, the more the speckles appear on the final render, it seems.
HOW TO DETECT THE PROBLEM: Often the speckling is very small and may pass unnoticed until it messes up your workflow. For instance, when an artistic filter grabs the speckles as well as the lines, or when they are still noticable on the final composite. Once the scan or render is in Photoshop, one can fairly easily tell where the speckles are. Make the scan or render a layer, knock out all white and then Stroke the layer edges with 4px red. The speckle dots show up clearly, as you can see here…
SOLUTION ONE (free): Switch to the Eraser tool and ‘have at’ those pesky spots manually. Not much fun and there are better things to do with 20 minutes of your time… per frame… cross a 600 frame comic…
SOLUTION TWO (free): Native to Photoshop is the Filters | Accented Edges filter. Try an Edge Width of 2, Edge Brightness about 28, Smoothness 5. There are two options here: i) hold back the Edge Brightness to 25 and they’re not entirely cleaned, just made very faint. Or ii) at a setting of 28 you totally remove them, but at the cost of making the lines thin. But thin lines are not a problem, if you can then run them through something which turns then into fatter ink lines thus…
SOLUTION THREE (free): Native to Photoshop is the Filters | Dust and Scratches removal cleaner. This is not ideal, and seems a bit of a crude old tool. It appears to work by blurring rather than actively selecting all ‘isolated dots, smaller than x pixels’. Line work will often turn rather grey after cleaning, and the picture will fuzz. But it does work and the speckles will be removed. Not ideal.
SOLUTION FOUR (free): The imaging experts at Polaroid released a free Windows tool to automatically clean up the dust on old Polaroid scans and similar photographic archival scanning of old slides. It worked by intelligently finding and masking each speckle. It then instantly removed the speckles. This freeware is long-gone, officially… but the great guys at Archive.org kept a copy for the world! pdsr1_0.exe can still be downloaded and still works fine for me in Windows 8.1.1. It’s standalone Windows freeware, simple to use but with user input on what speckle size to grab hold of, and it can also pass the final cleaned version over to Photoshop.
Drawbacks are: i) it ‘knows nurthing’ about PNG files; ii) it’s often difficult to stop the dust identification process from nibbling into the drawing/ink lines; iii) there’s no way to export the mask to Photoshop. As such, while it’s great for photos it’s not ideal for cleaning up line-art.
SOLUTION FIVE (paid): Martin Koch’s CleanUp Line Art plugin. Computationally identifies and deletes stray isolated dots and dashes in a line art image, at a specified pixel radius. 12 Euros with a free trial. I couldn’t get this working on 32-bit Photoshop CS6 on a 64-bit Windows system. Error messages lead me to suspect that its memory access coding means it will now only run under a 32-bit Windows install. This shows what it could do, removing strays without affecting the rest of the image…
SOLUTION SIX (paid): A slick modern Photoshop plugin is SRDx, and it had a Windows version about 18 months ago. The drawback is that, while it used to be a somewhat affordable $29, it now costs $49. It has a specific OpenCL 1.2 requirement for your graphics card. I could be wrong, but it appears to work like Martin Koch’s CleanUp Line Art by intelligently identifying stray specks ‘larger than x pixels’ and masking them. There’s a trial if you want to test it.
There are also about a half dozen ‘noise-buster’ Photoshop plugins for photographers, but they seem to aim to deal with camera sensor fuzz and chroma fireflies in the shadows, and thus don’t deal with quite the same problem.
Possibly some of the more advanced Mask plugins also have some kind of intelligent edge-detection of stray dots, but I want something simple and easy to use and I’ve always found them way over-complicated in the past.
Outside Photoshop, one possibility to look at for speckle removal and extraction on line-art may be the free open source Inkscape.
Some scanner software is said to come with speckle and dust reduction/removal software.
For Poser users, a switch away from using the old Firefly ‘Toon Outlines’ is now feasible, with the new Comic Book Preview mode giving good clean inks depending on what Display mode and lighting you’re in. However, ‘Toon Outlines’ is still useful as it gives you every single line on the 3D model and each line can be weighted in the Materials settings.
As a sometime photographer and old picture restorer it’s nice to have found the free Polaroid software, which works well and quickly for photos. But for what I need Photoshop’s native Accented Edges filter seems fastest and most effective. Though for most paper/pen artists it may slim down their hand-drawn lines too much.
For the future, it would be nice to have a Photoshop plugin that could transform a weighted spread of round tone dots into Moebius-style hand-drawn ink dashes. One could then run something like Pixeology’s Artistic Halftone into a shadows render layer, and then transform the resulting round dots into wobbly ink shading, thus…
The dots would become something neat like this, rather than smushy grungy cross-hatching…
Ideally, such a tool would auto-detect the gradient ramp and curve of the original shadows layer and also the angles of the outer edges, and then orient the individual dots-to-dashes to flow nicely. That’s the key drawback with engraver plugins, that they have no method of intelligently placing the shading lines onto a figure approximately as artist would have done. I see in several research papers that image processing researchers are working on this, but it doesn’t yet appear to have become a Photoshop plugin. Akvis Decorator might be able to do something like that, though I’ve only ever tried it with omnidirectional plain material and even then it takes an absolute age to run.