Please take me off the list Thanks
On Mon, Sep 29, 2014 at 12:00 PM, <[email protected]> wrote: > Send users mailing list submissions to > [email protected] > > To subscribe or unsubscribe via the World Wide Web, visit > http://lists.racket-lang.org/users/listinfo > or, via email, send a message with subject or body 'help' to > [email protected] > > You can reach the person managing the list at > [email protected] > > When replying, please edit your Subject line so it is more specific > than "Re: Contents of users digest..." > > > [Racket Users list: > http://lists.racket-lang.org/users ] > > > Today's Topics: > > 1. Is there any way to get the bit depth of a bitmap? (rrandom) > 2. Re: Is there any way to get the bit depth of a bitmap? > (Matthew Flatt) > 3. Re: rsound docs (Matthew Flatt) > 4. Re: typed racket, filters, and polymorphism (Robby Findler) > > > ---------------------------------------------------------------------- > > Message: 1 > Date: Mon, 29 Sep 2014 23:14:43 +0800 > From: rrandom <[email protected]> > To: Racket Users <[email protected]> > Subject: [racket] Is there any way to get the bit depth of a bitmap? > Message-ID: <[email protected]> > Content-Type: text/plain; charset=GB2312 > > Hi,I am recently working in the book Digital Image Processing with > racket. I want to know is there any way to get the bit depth or color > depth of a input bitmap in Racket? I found the get-depth method in > racket/draw,bitmap%, but it only return 1 and 32, that's not what i > really want.I input a bitmap whose bit depth is 8 but i got 32. > following is the code: > >> (send (read-bitmap "Fig0305(a)(DFT_no_log).tif") > get-depth) > 32 > > Is there anything I am wrong? Thank you! > > > ------------------------------ > > Message: 2 > Date: Mon, 29 Sep 2014 09:24:07 -0600 > From: Matthew Flatt <[email protected]> > To: rrandom <[email protected]> > Cc: Racket Users <[email protected]> > Subject: Re: [racket] Is there any way to get the bit depth of a > bitmap? > Message-ID: <[email protected]> > Content-Type: text/plain; charset=UTF-8 > > Racket libraries can read and write images of various formats and > pixels depths, but a `bitmap%` object always represents an image using > 1 or 32 bits per pixel in memory. > > At Mon, 29 Sep 2014 23:14:43 +0800, rrandom wrote: >> Hi,I am recently working in the book Digital Image Processing with >> racket. I want to know is there any way to get the bit depth or color >> depth of a input bitmap in Racket? I found the get-depth method in >> racket/draw,bitmap%, but it only return 1 and 32, that's not what i >> really want.I input a bitmap whose bit depth is 8 but i got 32. >> following is the code: >> >> > (send (read-bitmap "Fig0305(a)(DFT_no_log).tif") >> get-depth) >> 32 >> >> Is there anything I am wrong? Thank you! >> ____________________ >> Racket Users list: >> http://lists.racket-lang.org/users > > > ------------------------------ > > Message: 3 > Date: Mon, 29 Sep 2014 09:28:14 -0600 > From: Matthew Flatt <[email protected]> > To: C K Kashyap <[email protected]> > Cc: [email protected] > Subject: Re: [racket] rsound docs > Message-ID: <[email protected]> > Content-Type: text/plain; charset=UTF-8 > > When you install the package, you also install documentation for > RSound. You should be able to find it by selecting "Racket > Documentation" from the "Help" menu in DrRacket, by right-clicking on > an identifier in DrRacket that is provided by the package's library, or > by running `raco docs` on the command line. > > You can also find documentation linked from the "rsound" entry at > http://pkgs.racket-lang.org/, which goes to > > http://pkg-build.racket-lang.org/doc/rsound/index.html > > > At Mon, 29 Sep 2014 19:09:17 +0530, C K Kashyap wrote: >> Hi, >> >> I saw this nice racketcon video ( >> https://www.youtube.com/watch?v=DkIVzHNjNEA&list=PLXr4KViVC0qI9t3lizitiFJ1cFIeN2 >> Gdh&index=9) >> on rsound. I've installed the rsound package and have been able to run the >> example from the video. >> >> Is there a place that has mode documentation/tutorial on rsound? >> >> Regards, >> Kashyap >> ____________________ >> Racket Users list: >> http://lists.racket-lang.org/users > > > ------------------------------ > > Message: 4 > Date: Mon, 29 Sep 2014 10:40:08 -0500 > From: Robby Findler <[email protected]> > To: Konrad Hinsen <[email protected]> > Cc: racket users list <[email protected]> > Subject: Re: [racket] typed racket, filters, and polymorphism > Message-ID: > <cal3tdoprhresee2rxjw6x5jm5ksnkvqkjvat-a8ruikaarc...@mail.gmail.com> > Content-Type: text/plain; charset=UTF-8 > > Whoops, sorry: this is the same thing Konrad was talking about! Duh. > Well, hopefully the link is useful. > > Robby > > > On Mon, Sep 29, 2014 at 9:32 AM, Robby Findler > <[email protected]> wrote: >> Just in case, here is one piece of related work from the PL world and >> is probably a reasonable starting point for finding others' attempts >> at this problem: >> >> http://research.microsoft.com/en-us/um/people/akenn/units/ >> >> Robby >> >> >> On Mon, Sep 29, 2014 at 3:44 AM, Konrad Hinsen >> <[email protected]> wrote: >>> Matthias Felleisen writes: >>> >>> > Your message points out where gradual typing badly fails. >>> >>> Not just gradual typing. I am not aware of any good unit >>> implementation in any type system, with the exception of F# and Frink >>> whose type systems were explicitly modified to add unit checking as a >>> special case. Dependent types should permit a good solution, but I >>> haven't seen it done yet. >>> >>> The reason you need dependent types is that the product of two >>> measures is another measure with a new unit, so you must be able to >>> construct new types (representing units) from values. For example, a >>> length divided by a time yields a speed. Once you can do that, scaling >>> a unit (e.g. from meters to kilometers) becomes a special case. >>> >>> > In this specific case, you have two aspects of dimensionality: >>> > dimension per se (I am sure there is a word for it) and the chosen >>> > unit to represent it. >>> >>> The two terms used for this distinction are in fact "dimension" and >>> "unit". >>> >>> > If someone writes (area-of-rectangle 1 [mm] 1 [km]), there is >>> > nothing wrong with it -- except that the type checker should insert >>> > a coercion from mm to m and from km to m (multiplying/dividing by >>> > 1,000). >>> >>> That's a topic of hot debate in the scientific computing community. >>> Some argue that the type checker should consider your example as an >>> error, and not do any implicit conversion. The motivation is that the >>> expression you used is more likely to be a mistake than the meaningful >>> use of expressive language, since best practices recommend to use a >>> minimal set of units inside any piece of code. >>> >>> Anyway, that's a minor detail. If your type system can handle >>> automatic conversion, then it can also handle its absence. >>> >>> >>> Alexander D. Knauth writes: >>> >>> > What I had in mind was for the structs to be available at run-time, >>> > but that ideally the optimizer could take them out for the >>> > intermediate operations and put them back for the final result. >>> >>> You are actually adding a very Racket-specific requirement to the >>> already difficult units-as-types problem: the interplay between a >>> typed and an untyped dialect of the same language. I agree this would >>> be nice to have. >>> >>> Konrad. >>> ____________________ >>> Racket Users list: >>> http://lists.racket-lang.org/users > > > End of users Digest, Vol 109, Issue 76 > ************************************** ____________________ Racket Users list: http://lists.racket-lang.org/users
