Ahh, I intend that this be my last post on the subject, because it is pretty much OT for this list, but I re-read the bug report and saw a paragraph that was there before, but seems to have sunk in now:
` Fontconfig has nothing to do with presenting the glyphs to the user, it simply selects the fonts. The bug you are seeing (and, yes, I agree that it is a bug even if white text on a black background is wrong) is due to limitations in various rendering libraries, like Xrender, cairo et al. ' On Saturday, February 03, 2018 09:14:45 AM [email protected] wrote: > On Saturday, February 03, 2018 09:02:10 AM [email protected] wrote: > > I did find a bug report not too long ago for some application which > > actually confirmed the bias I described, and described how that worked > > (in general terms)--I'll make a cursory search or try to remember where > > I found that, and, if I do, I'll post it here. > > Ahh, that was easier than I expected--here are my notes after reading that > bug report (some time ago)--I did not re-read it today to see if anything > has changed. The comments immediately after the [[<URL>][<Page Title>]] > are my own, the things after the ` are quotations from the bug report. > > * [[https://bugs.freedesktop.org/show_bug.cgi?id=13431][Bug 13431: > Summary: Gamma not taken into account, white on black hard to read]]--this > confirms my observation of the problem, but my explanation (iirc) predates > gamma correction (iir/uc)--my theory of the cause of the problem is that > anti- aliasing sort of "assumed" that the normal view would be black on > white, when it was applied to white on black, it should have somehow > considered the other "color" (black or white) to be the basis--because it > didn't, fewer pixels are colored white when viewing white on black as > opposed to the number of pixels colored black when viewing black on white. > I don't know if the problem still exists--it probably does in at least > some places, and, I still have more difficulty reading white (or a light > color) on a black (or dark background). ` > When doing antialiasing, fontconfig-based renderers do not take gamma into > account and assume a linear color space. This make black on white text > difficult to read at small font sizez. > > ... > > The reason is that the stems of the glyphs are thinner than a whole pixel. > Therefore, they get a fractionnal value. For example, the pixels on the > lower part of the stem of the 'f' get the pixel value 151/255 in black on > white, and 104/255 in white on black (and 104+151=255). With the usual 2.2 > gamma, this makes respectively 32% and 14%, which gives a contrast of 68% > for black on white, and 14% for white on black. > ' _______________________________________________ arm-netbook mailing list [email protected] http://lists.phcomp.co.uk/mailman/listinfo/arm-netbook Send large attachments to [email protected]
