From alobo@ija.csic.es  Thu Oct  4 13:29:58 2001
From: alobo@ija.csic.es (Agustin Lobo)
Date: Thu, 4 Oct 2001 14:29:58 +0200 (MET DST)
Subject: [Rd] Re: RFC: package pixmap
In-Reply-To: <15292.20438.705267.252746@galadriel.ci.tuwien.ac.at>
Message-ID: <Pine.OSF.3.96.1011004141759.19722H-100000@ija.csic.es>



On Thu, 4 Oct 2001, Friedrich Leisch wrote:

> 
> You have 900 columns and only 270 rows, hence you should have a
> vertical rectangle that is approx. 3 times as wide as high.
> 
> The difference to calling image() on a matrix is deliberate: if you
> store a picture as a matrix (as usual), then you'd expect element 1,1
> of that matrix to correspond to the upper left corner. That is
> different from what image() does, because it was designed for doing
> the right thing for matrices produced by, e.g., outer() ... [at least
> I think that's the reason for image() rotating the matrix].

I agree with the point that the upper left corner must be the
1,1 cell in the matrix for a "natural" display of the matrix
as an image. But this does not mean that the matrix should be rotated.
In all image processing packages that I know of, an image with
200 cols and 100 rows is displayed as a horizontal rectangle. Note
that, if there is geometric correction to a geographic projection,
the columns go W to E as left to right and the rows N to S as
top to bottom. In fact,
the "natural" display should follow the same geometry than print,
i.e.,

> matrix(1:12,ncol=6,nrow=2)
     [,1] [,2] [,3] [,4] [,5] [,6]
[1,]    1    3    5    7    9   11
[2,]    2    4    6    8   10   12
> 

should be displayed as a horizontal rectangle.

Of course you can do it as you want because this is your package,
but are you sure that you want it the way it is?

Regards,

Agus


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[Rd] Re: RFC: package pixmap
Agustin Lobo