In the UK, there is plenty of computer systems that refuse to acknowledge that people or places can have non-ascii chars in their name, and ask you to correct them.. or even refuse to work possibly because they are comparing broken different encodings of them. Even paying tax by debit card seems to be impossible with their chosen payment processor if the name on your card or parts of your address does not match the constraints of the english alphabet.
Avoding any international characters, both when registering addresses and when inputting them in forms ends up being the path towards hopefully being able to spend money with credit/debit cards though. For various other non financial forms fuzzing the systems with what should be common enough european text and laughing as it fails is safer fun though.
Some years back I built a family of fonts around the idea of anti-aliased raster fonts realized as regular truetype outlines - http://pippin.gimp.org/0xA000/ - in which some variants of the family is designed to be crisp on many integer multiples of the base design size.
The L component of CIE Lab is not linear, it has a similar non-linearity to sRGB due to one of the aims of the design of the CIE Lab space is to be perceptually uniform.
The development version of GIMP (the 2.9 series) - which will be come 2.10 uses GEGL which always does scaling with linear light encoding; as well as premultiplied alpha, regardless of what color "mode" the project is in. Getting scaling and resampling right in all cases is easier than retroactively fix the prevalent bad habit of non-linear compositing..
γ-correct scaling is good, but will GIMP support area-downscaling? I.e. if you downscale three times, you average each three (or 3×3 if both axes) pixels, not choose any one of them. Currently you get moire patterns, and "interpolation" is not a correct way to do downscale more than ½.
It already does, in git master GEGL/GIMP does averaging of pixels contributing in the area when scaling down. The previous development releases in the 2.9 series would only do proper downscaling for the nohalo and lohalo samplers. But since may of this year GEGL also does an area/averaging box filter for cubic and linear samplers.
Pure averaging isn't the best way to go, that's basically a box filter. You can use the interpolation kernels, but you need to widen them proportionally to the amount you're downscaling. Instead of your bicubic working with a 4x4 area, for 3x downscaling it needs 12x12. Ideally for ½ scale you should be using 8x8 already.
A box filter for scaling down cubic and linear is much better than using impulse filters with the interpolated values at the floating point coordinates in question. If someone wants to improve the code in GEGL (used for rotations, scaling, perspective transforms, live on image warping as well as other transforms in the development version of GIMP) the relevant place to put it in is here:
For the linear case a "tent-filter" instead of a box filter would be really correct, a similar box filter function exist in cubic. Both of these receive a reverse jacobian matrix indicating the shape and extent of surrounding area in source image to sample from.
To eliminate moire artifacts you need to remove all frequencies above the Nyquist limit. In resizing applications there are two Nyquist limits, one for the input and one for the output; you need to filter for whichever is smallest. When upsizing the input limit is always smallest, so the filters can be constant. When downsizing the output limit is smallest so that's the one you need to tune your filter for. That's why I suggest widening the interpolation formula when downsizing.
I've been meaning for years to make a blog post on this subject. I don't think many people realize that an interpolation formula is also a filter formula, and that it can be manipulated and analyzed as such.
I have my own implementation of the classic filters that I use for my resizing tasks. It works in linear gamma space as suggested in the article. I've implemented lots of different algorithms, and I've settled on Lanczos-5 as the best overall compromise. One interesting observation, the Catmull-Rom bicubic interpolation is nearly indistinguishable from Lanczos-2.
This relearning problem goes both ways. People trained on GIMP tend to find Photoshop annoying and difficult to use - because they have to relearn. People accept spending extra time and struggling when learning a new skill; and are frustrated with tools (or really themselves) when something they think they know how to do suddenly is difficult.
I'm sure that there is a learning curve for people going from Gimp to Photoshop. In my case, going the other way, after over a decade, I still find Gimp a massive pain in the arse. It's not just that it's "not what I'm used to", it's that it's bad.
Recently I had to make some end-credit cards for a short film - ie. white writing on black backgrounds. Gimp managed to make even that painful. Things like, placing an immovable dialogue over the handles of my text box so I can't get at them. If I try to replace text, it reverts to its arbitrary choice of font / size so I have to type new text in the middle of my existing text, then delete the original. No "duplicate layer" shortcut. Just gratuious annoyances that are good for nobody, and bad for everybody.
Edit: I have a feeling you might be a Gimp dev, in which case I should be more grateful for the work you do, which I still use and benefit from even though the UI frustrates the hell out of me.
Edit2: I just found the Duplicate Layer shortcut. Not sure how I missed it before.
The work you might have heard about GEGL - is all about providing foundations for such non-destructive editing. The highlighted split-view / curtain preview in the blog post is implemented using these new capabilities provided by GEGL. Adding new features that cement themselves as new things in the file format is part of GIMPs roadmap after GIMP-2.10 / 3.0. 2.10 / 3.0 are aiming to provide the same functionality that GIMP-2.6 / 2.8 provided but with GEGL as the core and thus higher bitdepth.
GIMP's new (though not actually young) engine - GEGL, contains ffmpeg frame sources and sinks, provides a good abstraction for creating interfaces better than GAP for animation or video editing - see https://www.youtube.com/watch?v=GJJPgLGrSgc for an example of a video that has been edited and encoded using GEGL this year.
Synfig focuses on more cartoon based vector animation. What GEGL provides good foundations for doing is video editing/compositing with keyframed properties for filters.
As mentioned in the linked article of this story - having an eco system of applications using GEGL would benefit both these applications and GIMP - since they would be sharing image processing operations and plugins.
Blender's node system can do compositing and basic video editing. Another free software graph based/dataflow system that can be used as a basis for such video editing and fx is GIMPs new engine GEGL; this goat filled video presented at this years libre graphics meeting was edited and composited using software based on that stack https://www.youtube.com/watch?v=GJJPgLGrSgc
