From e0c6872cf40896c7be36b11dcc744620f10adf1d Mon Sep 17 00:00:00 2001 From: Norbert Preining Date: Mon, 2 Sep 2019 13:46:59 +0900 Subject: Initial commit --- info/write-w | 90 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 90 insertions(+) create mode 100644 info/write-w (limited to 'info/write-w') diff --git a/info/write-w b/info/write-w new file mode 100644 index 0000000000..ce917f9293 --- /dev/null +++ b/info/write-w @@ -0,0 +1,90 @@ +This file is README.WRITE-W. It is extracted from a correspondence +message sent during September, 1986. + +From: Neenie Billawala +Subject: Re: Metafont parameters for Imagen 24/300 + (This discussion is also relevant for the LN03) + +How to get the CM fonts to work better on a "write-white" machine +================================================================= + + +The problem in getting a like result with write-white(ww)/write-black(wb) +machines from the same pixel pattern lies in the fact that the effective +size of each pixel differs; the size is typically smaller in ww machines. +This means that you won't get the same variations in line thickness. + +Theoretically, one pixel on a 300dpi printer should have a width of 1/300 +of an inch. On a ww machine, it's typically less; on a wb machine, +it's usually a bit more. So the gradations of thickness may look +something like the following: + +# of pixels "ideal width" ww width wb width + + 1 1 * 1/300inch .8 * 1/300inch 1.2*1/300inch + 2 2 * 1/300inch 1.8 * 1/300inch 2.2*1/300inch + 3 3 * 1/300inch 2.8 * 1/300inch 3.2*1/300inch + 4 4 * 1/300inch 3.8 * 1/300inch 4.2*1/300inch + 10 10 * 1/300inch 9.8 * 1/300inch 10.2*1/300inch + +So, you can see, the greater the number of pixels, the less important +the .4 pixel difference becomes. The greatest discrepancy and problems +occur with lines one pixel wide, where the % of difference is the greatest. +Given these limitations, it is not possible to get exactly the same +results on two such separate machines. + +Increasing the amount of "blacker" has the effect of adding that +absolute amount to certain values; i.e., blacker:=2 would always add +2 pixels to the stem, no matter the resolution. + +A while back, someone came by with the same problem for a similar machine. +We tried 1) some higher settings of blacker 2) selectively adding blacker +to some values 3) setting a mimimum line thickness. Both 1) and 2) often +created unwanted character distortions. The (tfm) widths wanted to be +the same, and when e.g., each line in a character was increased by one; +the shapes were often distorted, counter (inside) shapes seemed to suffer +the most. A first attempt with 3) showed promise, and though the result +was not as dark as the wb machine, the feeling of CM was retained. +However, in the first attempt, we did not manage to change all of the +thicknesses to 2 pixels. DEK made a global correction, which should keep +minimum thicknesses to 2 pixels. Looking at the pixel patterns, this fix +appears to work. However, the man who has the ww printer and who originally +came by with this problem, is part of the University and has been traveling, +so I haven't seen any concrete results yet. Such is the way of Academia! + + +Appendix: (Pierre A. MacKay) + + +Roughly speaking, the reason for this problem is that the black dot in +a write-black machine has a roughly round shape, and naturally tends to +overflow the minimum dot size. The dot on a write-white machine has an +incluse square shape, and tends to be diminished by an oversize white +dot unless the print engine is perfectly focussed. + + ..... + ....... . . + ......... ..... + ......... ..... + ......... ..... + ....... . . + ..... + + Write-black dot Write-white dot + +The ./cmfonts/mf directory contains an adjusted font_setup file. The +changes are found in 2 lines of the def with the comment +"% "WRITE WHITE" ONLY!". Add the line input white_setup to your file +of mode_defs (or use ./utilityfonts/bases/modes.mf, which already +has it), and in any mode_def for a write-white device, add the line + +let font_setup=white_setup; + +as the first line of the mode_def for any write-white device +(see the RicohFourZeroEightZero mode_def in modes.mf). + +Directories +[ + ./utilityfonts/bases + ./cmfonts/mf +] -- cgit v1.2.3