Outlining - basic (very) approach
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WARNING: assuming you have CLEAR A (and B) side figurine at separate layer - ie. clear = only figurine, no white background etc.)
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1.
Set-up layer named "Outline-A" just beneath layer with your (clear!) figurine
2.
While being at "Outline" layer select the above layer (the one with figurine) => Ctrl+Left click layer (Photoshop shortcut, should be similar in GIMP or other raster graphic software)
Now, having selected area, all what we have to do is to put into work some standard Photoshop functions (some experiments would be helpful as SIZE/SCALE of your project are crucial). Anyway assuming that you are working with already finished and scaled figurine placed at standard page (A4) and your figurine is ca. 30mm tall:
3.
Expand selected area (Select/Modify/Expand) - like +15-20px
4.
Smooth (Select/Modify/Smooth) - like 5, but fell free to experiment, but THIS one is crucial as it straighten/smooth-up some gapes and gives more "rounded" overall shape!
5.
Contract (Select/Modify/Contract) - like 5-10px =>experiment!
6.
Fill processed selected area
Fill (Edit/Fill) the area with pure BLACK (CMYK 100K)
7. Deselect (obviously)
And VOILA! - you have enlarged and smoothed BLACK area of your figurine just beneath (layer below) your figurine!
Received black area should be ca. 5-10px (depending on variables you set) bigger than your figurine - so standing out area is in fact an "outline"
You can do some manual corrections here and there of course:)
PLEASE NOTE:
sometime (style/quality of figurine depending) it's better to Expand and then (after Smooth) to Contract, and sometimes this step could/should be IGNORED. Please feel free to experiment with variables, so you can achieve thinner/thicker outlines for example.
Good thing is that:
-this BLACK area is placed at separate layer, so you can freely change if needed it and then COPY it to B-side, use it (via copy and drag etc.) with other similar figurines (like for mods)
-then cohesive BLACK area BENEATH figurine covers ALL the SMALL pits/holes (like space between legs. between body and weapons etc.)
Bad thing is that this technique is adding additional layer to each figurine's side, so the working file is larger (but, c'mon... srlsly?
In my case I always have similar "layers structure" for each figurine at the final page (assembled into Groups in Photoshop):
Group Figurine xyz
-Figurine xyz A-side
-Outline xyz A-side
-Figurine xyz B-side
-Outline xyz B-side (it's de facto Outline-A copy!)
(then there is obviously also a linked TAB Group with adequate text/description if/where needed, but that's another story:)
Link these layers or groups (if working with more than one figurine) accordingly so you can freely move and transform your whole figurine or just A or B side (like horizontally, vertically etc.) or shift figurine or groups of figurines and reposition them across the page.
Last but not least:
You might want to DEFINE some ACTION (Photoshop) or PROCEDURES/FUNCTIONS (not sure what are the names/terms in some more exotic software like GIMP etc.) - I'd really recommend to play with these features, so after you determine your preferred/best outline parameters you can automate the whole procedure with just a 1-2 clicks or even better with simply one keybind!
(Actually you might also want to add some more steps to auto-generate tabs and even add some description text - but that is kinda more sophisticated so I'll skip this topic here:)
Now, just to be frank - described technique is rather very BASIC one, just a first step...
You may want to add some more automated functions in order to obtain more rounder/smooth areas/outlines
You should check out this and other techniques just to choose the one which suits better your needs;
Then please remember that quality of figurine itself plays significant role here /ie. crisp and clean boundaries/- but combined together with some automation (like ACTIONS) it gives some really head-start and spares decent amount of time.
Actually it is possible to further automate the whole process (like adding properly positioned tabs, tab's predefined text-descriptions and bend lines)
Hmm...
Not sure if it was a)readable b)helpful - perhaps some sort of video/webinar would be more legible:)