Keen-eyed observers will have noticed by now that much of my creative output has a certain finish, a look or style that is present to some degree in almost every design I make. This is the result of two filters that I frequently use while processing images using the fabulous and free image editing software that is GIMP. I have discussed these filters in this blog before, I think, but let's look at them again, and then follow it up with an examination of the subsequent posterization I often use before a design makes it on to a product in my store.
Mean Curvature Blur (MCB)
I fell in love with the Mean Curvature Blur filter available in GIMP very early in my creative rebirth during the mid months of 2020. Like any blur filter, MCB destroys detail but does it in a flowing and directional way that preserves some definition. Of course, it can be be applied more or less using a sliding scale; in the example here it has been applied very heavily for demonstration purposes. Doing this to a photo confers a couple of advantages. One is simply the look, which has an organic quality that I like a lot. The other is that using this filter opens up the possibility of utilizing lower resolution photos. It's well known that enlarging a JPG too much will result in obvious artifacts and pixelization that is particularly noticeable around high-contrast edges. One way around this is to spend money on "up-rezzing" software that uses algorithms to invent detail. The way I deal with it is to apply some MCB judiciously - a very little before enlargement and then another dose after, just enough to smooth out those artifacts while preserving as much detail as possible.
Next step, usually, is to apply the Cartoon filter. This filter outlines edges in black, with control over percentage of black (how much) and radius of black (how wide). When used in conjunction with MCB, it produces a very sinuous effect that often makes surfaces appear pitted and dimpled, sometimes even intestinal. It's a weird look that hits just the right spot of my brain. I also adds some crispness and definition to an image that has been heavily treated with MCB and thus inherently blurry.
Finally, I often use the Posterize filter if the design is intended for print on a shirt or some other product at my online store, Lazy River Design Works. When I first started posterizing images, I did so "by hand," meaning that I didn't simply use a one-click filter. Instead, I selected a series of colour ranges, destroyed all detail within each range by dropping its Contrast to 0, and then assigned each selection a single colour. I wrote a blog post about this very topic: A Look at Cartoonification. I believe that treating a photo in this way, or at least using the Posterize filter as an almost final step, makes a design more suitable for printing. I have noticed that photographs with all their rich detail do not necessarily look that good when printed onto fabric or any other medium that has a relatively coarse surface texture. A Posterized design, however, confers a graphic, screen-printed quality that lends itself very well to printing on a range of mediums. Another advantage is that Posterization creates hard edges for everything in the image and so adds crispness. At present, I'm using the Posterize filter that is available in a very large suite of filters and effects from G'MIC. It's not perfect, with the biggest problem being that it tends to deaden colours (see above) even when "Normalize Colours" is used within the filter. That's an issue that can be fixed fairly easily, though, by hand picking the various colours and tweaking them.
Below is a gallery with the same photo at the various stages of filtering. 1 - No Filter, 2 - Mean Curvature Blur, 3 - Cartoon, 4 - Posterize Clicking on the gallery will expand the images and let you see detail more clearly.
I hope this has provided some useful, or at least mildly entertaining, information.