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diff --git a/libglitter.7 b/libglitter.7 index a446eeb..1e32967 100644 --- a/libglitter.7 +++ b/libglitter.7 @@ -84,6 +84,73 @@ at the beginning of its execution to enable any implemented and supported hardware acceleration. This may however be an expensive process, and may not be desirable for all applications. +.SH APPLICATION USAGE +Some users are more sensitive to colour while other users +are more sensitive to shape. Subpixel-antialiasing, if done +well, is a good option for users that are more sensitive +to shape. However, for users that are more sensative to +colour, subpixel-antialiasing renders glittering, and reading +subpixel-antialiased text can be headache inducing, especially +if implemented poorly or if the monitor doesn't have high +enough pixel density (for some users just above normal laptop +pixel density can be fine, but for others, not even 4K on a +laptop is good enough). For these users, greyscale-antialiasing +is a much better option. For this reason, applications must +not for subpixel-antialiasing, and should even only used it +if the user explicitly requests it. .PP +Hinting is another important issue. For aliased text, hinting +is critical to ensure that strokes do not disable because they +are not wide enough, but also it is important so that a stroke's +width is not doubled because it is a bit wider than a pixel or +not aligned well with the pixel grid. Hinting attempts to align +the font outline with the pixel grid. For greyscale-antialiased +text, hinting as not as important, but it removes blurring and +dim strokes. For subpixel-antialiased text, hinting is not as +important as for aliased text, but it is more much important +that one greyscale-antialiased text. For subpixel-antialiased +text, hinting removes fringing (colours along the edge of a +stroke) and miscoloured strokes, strokes can even disappear: +for example, if the stroke only hits blue subpixels, but +should be rendered as pure red (the primary colour) on black, +there will only be black, as that is what primary red muliplied +by primary blue results in. Applications are discourage for +using subpixel-rendering on non-hinted text unless that user +explicitly says it he wants subpixel-rendered text even it will +look bad (presumably to see how it looks). Subpixel-rendering +may also be a bad idea on coloured text. +.PP +Because subpixel-rendering is entirely dependent on the subpixel +layout, it is inappropriate to use subpixel-rendering unless the +subpixel layout is known, and the text is rendered specifically +for that subpixel layout, or if the resulting raster is scaled +post-rendering, for example if the output native resultion is +3840x2400, but the computer outputs 1920x1200, (and the output +is scaled up by a factor of 2 per dimension). The purpose of +subpixel-rendering is defeated in such situations. +.PP +For best result, the application shall take into consideration +both the output's vertical pixel density and horizontal pixel +density, subpixel order, subpixel layout, output scaling, the +output's colour model's transfer function (gamma compression), +hinting, and text and background colour. If text is rendered with +light on dark colours, but the font is not designed for reverse +type, the application may desire to apply more aggressive hinting. +The application shall also output the text image in the colour's +native colour model: as the primary colours' chromacity may +differ from sRGB, it is possible that when outputing colour it +is intepreted as sRGB, and converting to the output's colour +model, which may change the activation level on the subpixels +as compared to how it was rendered. +.PP +Applications should be aware that the user's may use different +monitors and may therefore need to render text differently +depending on which output the text is being displayed on. This +may even include changing the text's pixel size, which can be +very problematic (depending on the context) if the text is +split over two output; however the user probably not reading +the text if it is split over two outputs, so simply basing +the pixel size of one of the monitors or averaging them is +probably good enough in that case. .SH SEE ALSO .BR libfonts (7) |