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Re: Image[], Graphics[Raster[]]

  • To: mathgroup at smc.vnet.net
  • Subject: [mg100338] Re: Image[], Graphics[Raster[]]
  • From: "Luc Barthelet" <luc at tirnua.com>
  • Date: Mon, 1 Jun 2009 07:09:33 -0400 (EDT)

I think that the documentation on how to integrate graphics and images 
from the new image processing features in V7 is not to par with the rest 
of the documentation. Image Processing feels a bit of an orphan in V7, 
it makes sense, since it is new.

Some suggestions:
1-   guide/CombiningGraphics could show how to use an image in a 
Graphics[] or as a background of a plot
3 - "Basic Image Processing tutorial ", "Image", "Import" could 
demonstrate our to mix images and graphics
2-  "Import","Show","Graphics","Inset" documentations could explain more 
clearly that Import[filename,"Graphics"] will import a file the old way 
and show examples of integration.

Luc


-----Original Message-----
From: Jens-Peer Kuska [mailto:kuska at informatik.uni-leipzig.de]
Sent: Sunday, May 31, 2009 3:33 AM
To: mathgroup at smc.vnet.net
Subject: [mg100338] [mg100284] Re: Image[], Graphics[Raster[]]

Hi,

>
> 1. Is Image[] any different than Graphics[Raster[]] that I'm more
> accustomed to?

No it has a fixed data range, i.e., "Byte" is [0,255], "Real" [0,1]
while Graphics[Raster[]] can handle undestructive every thing.

>
> 2. If not, what was the point of introducing Image[]? Was it any 
effort to
> provide a more streamlined set of commands all revolving around 
Image[],
> e.g., ImageRotate[], etc.?

The reason was a faster display of the bitmap. With fixed data range
the FE don't have to do a scaling of every pixel.

>
>
> 3. Image[] somehow upsets my unified view of Mathematica. That is, I 
like
> to try to "think" like Mathematica, and so I understand that all 
commands
> like Plot[], ListPlot[], etc., reduce to a Graphics[] object in
> FullForm[]. Similarly, I can build my own type of plotting function 
with
> Graphics[]. Most importantly, I can combine many different types of
> objects into a single Graphics[]. Am I correct that Image[] represents 

> then a completely new display object? If so, is there a way, for 
example,
> to have an Image[] and then draw across it with an Epilog rule like 
you
> can do with Graphics[]? It seems a major setback if Image[] and 
Graphics[]
> cannot be readily mixed.
>

Oh mixing is easy:

img = Import["http://www.stephenwolfram.com/img/home/sw-portrait.jpg";]
Graphics[
  {Image`ToGraphicsRaster[img][[1]],
   Circle[{110.5, 110.5}, 10]}]

draw a circle on the image.

> Anyone out there to make the case that Image[] represents an important 
new
> capability?

No, it make many things more complicated, and a lot of image
processing tasks impossible -- registration for example ..

I see it as a little worse than the usual "new command that
> does same thing old stuff did" because it seems to lose the capability 
to
> mix Graphics[] and Image[].
>
> Please inform me if I'm completely off base. As I said, I'm just 
digging
> into Image[] now for the first time, and I'm a bit confused about 
possible
> merits---please do inform!

There is no merit, it make many things worse than the original
Graphics[Raster[]]

Regards
  Jens




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