Talk:PostScript

ps edit

What tools are available to edit postscript files? To downsample or remove embedded images? -69.87.200.8 23:56, 21 September 2007 (UTC)

I always used vi. Gah4 (talk) 23:26, 9 September 2019 (UTC)

Use of Homogeneous Coordinates

The article claims that translation (!) and rotation are handled using a "2D Transformation Matrix". I doubt that many implementations will do this. It supposedly is a lot easier and more efficient to use a 3D matrix instead and a technique called homogeneous coordinates. This allows rotations and translations to be combined easily into a single matrix that needs to be kept as current context. Looking at the Ghostscript API suggests that this it at least the way it is handled in Ghostscript. See also http://merganser.math.gvsu.edu/david/psseminar/index.html 84.154.14.147 (talk) 15:40, 12 May 2008 (UTC)

What is used is technically an affine transformation, which can be encoded in 6 scalar coefficients or a 2×2 matrix $A$ plus a 2-element vector $\mathbf {b}$ (the map being $\mathbf {x} \mapsto A\mathbf {x} +\mathbf {b}$). The PostScript (and PDF) documentation rather prefers a presentation that embeds all the data in a 3×3 matrix with three fixed elements, which is why they speak about the "current transformation matrix"; in principle this amounts to using homogeneous coordinates, but I doubt any implementation does the calculations that way, since the extra fixed elements don't carry any information. 130.243.68.184 (talk) 15:30, 9 September 2019 (UTC)

Mention of Units

Previously there was a more accurate description of the unit of length before a lot of the technical detail on postscript was removed from the article.

Given that this material was removed, is the mention of the units of length even relevant?

Also, as cited by the PLRM (the all important and accurate red book):

"Note: The default unit size (1/72 inch) is approximately the same as a "point," a unit widely used in the printing industry. It is not exactly the same as a point, however; there is no universal definition of a point." (Pg 183, Postscript Language Reference Manual, 3/e)

ergo: claiming the unit is typographical points is inaccurate. Akunokuroneko (talk) 04:35, 5 December 2008 (UTC)

I thought of the same thing, and now I can see, someone else already mentioned this. Yes, indeed, the PostScript document specifically says that 1/72 inch isn't a point. I believe this should probably be fixed in this article, although I am not sure the best wording to use. --Zzo38 (talk) 05:38, 10 August 2020 (UTC)

Why is "Before PostScript" in section "Use in printing"?

Before PostScript, PostScript wasn't used in printing, which seems trivially obvious. Maybe "Effects/Printing without PostScript"? Theanswertolifetheuniverseandeverything (talk) 18:28, 16 June 2018 (UTC)

It serves to put the role of PostScript into a historical context: what difference did it make when PostScript was introduced? One could make an argument that such content rather belongs in a "History" section, but that section is about the evolution of PostScript as a language, and well-written as it stands. 130.243.68.184 (talk) 15:57, 9 September 2019 (UTC)

%!PS

As far as I know, %! is supposed to be enough for a PostScript printer to know its input is PS. It seems, though, that many HP printers just check the %. Print a plain text file starting with %, and nothing comes out. Gah4 (talk) 01:07, 12 July 2019 (UTC)

Did you try adding a form feed? Does still nothing come out? --Zzo38 (talk) 05:38, 10 August 2020 (UTC)