The problem here is that is not possible to understand perfectly the recommendations about digital painting when it is destined to print… in some cases 300 ppi is not sufficient, for instance, to certain comic arts in many cases we talk resolutions as 600 ppi or 1200 ppi… but is, important to have in mind also… that the format in these cases maybe inferior to A4 or max …
When I have chosen 3500 x 3500 pixels format I have thought in an intermediate ISO format among A4 and A3.
We must think also that the brushes have a certain elasticity to respond the increases or decreases grades (+/- 70%).
Here is a question that I think is critically important when setting up for making digital painting: What zoom factor should be used for evaluating the marks made by brushes, in particular when evaluating the micro-tonality that our eyes interpret as texture?
The answer probably somewhat depends on what kinds of texture one wants to create. Personally I’m interested in creating textures and colors that resemble the marks that pencils, crayons, charcoal, oil and chalk pastels, and also “watercolor and ink” make on various types of paper.
It doesn’t matter how nice digital “texture” might look at 100% zoom on the screen. What counts is what the texture looks like when sized on the screen to match the size of the final print.
My screen dpi is 100px/inch. So if the final print has 300dpi, on my screen the correct zoom factor for evaluating texture (the zoom that makes the print on the screen have the same number of pixels per inch, as the final print will have dots per inch) is 100/300, or 33.333% zoom.
Yes, is correct the approach and is so that I do normally to verify if the brush is good or rather bad or it must some changes.
Having settled on dpi/ppi and a final print/digital file size, and a zoom level for evaluating brush marks and resulting images, the next question is “What sizes and styles of brushes are required to make marks that emulate the desired textures?” Consider using a pencil to make a quick sketch for establishing composition:
The left side of the above image shows “pencil sketching” marks at 100% zoom, and the right side shows a quick sketch, showing the size of the marks relative to the actual canvas size.
OK, the brush that I used to make the pencil marks in the image above is the 16px by 16px “Pencil Sketch” brush from the current default GIMP brushes (one of the brushes I said I didn’t think I’d ever use ). I created a preset for the brush+brush settings+dynamics, that sets the “brush size as painted” to 8px - half the size of the actual brush. The five lines in the upper left corner show the default marks from the preset, and the remaining lines show variations from small changes in various parameters.
The method that you have used is correct and is used for many digital artists but many times via unconscious way or dictated by the empiric experiences
When you have used 8 px instead than default size brush (32 px), you are calibrating the line stroke for the situation and the intention that you prefix obtain as the final result.
The default Pencil brushes are an old design that I made circa 8 years ago… and then I have thought other usages as pencil line stroke and as to shading too… the real pencil can be used in different ways, not only to hashing but also to create large strokes to shading and not only.
To understand my motifs is useful to see this short video about “How to Sharpen a Pencil For Drawing”
So what does all this have to do with making a new set of default brushes for GIMP? I think designing a general purpose brush set is an extremely difficult task. We already mentioned that one parameter is how approximately large the canvas will be. @Americo’s decision to base the brushes around a 3500px by 3500px canvas seems to be a nice “average” canvas size.
Yes, is a good format to begin… but is important also discuss the methods and approaches how the brushes are effectively used in digital painting nowadays for the mainstreaming and of the other tendencies and usages, for instance how the artist’s style is influenced by certain effects that the brush is emulating … mainly that we have complex brushes based on .gih format.
Another parameter is the user’s personal style - style hugely dictates what counts as a “basic brush”, it seems to me.
Certainly, this is the more important aspect… the confidence/skill that some artists could have with their tools are in reality the more important thing… for instance, Alberto Breccia, a drawer, and cartoonist artist Uruguayan/Argentinian has used the Gillette to drawing with ink.
I know @Americo is actively revising the Basic brush pack, and so there will eventually be different/additional brushes. So this is a suggestion that there be a brush or two for pencil sketching. Right now the smallest brushes in the Basic brush pack are 24px by 64px, and the marks made by these smallest brushes are a bit “gritty, inky” - not sure what the right word is, but definitely not the sort of smooth crumbly marks that are made with a pencil.
In effect, the Pencil brushes are a bit ‘gritty’… but the pencil aspect when seeing very near is also a bit ‘gritty’… so, is important the setup of the pencil to create an aspect more near of real tool. For me, many brushes could be used also to emulate pencil, for instance, the crayon or charcoal tips in certain setup conditions have good results.
My suggestion… when we drawing or painting is to have a second view, but in the real size to understand how our brushes are working effectively.
Another suggestion is proofing also these brushes without ‘angle x direction’ enabled.
So I would request the addition of one or more brushes for making pencil marks, including a “pencil sketching” brush.
Perhaps, we need to discuss also the useful presets to emulate certain texture tools… but this a next chapter.