<p>I'm teaching linear algebra, and thought I'd show my students <a href="https://www.ocf.berkeley.edu/~fricke/projects/israel/paeth/rotation_by_shearing.html" rel="nofollow noreferrer">Paeth's rotation by shearing algorithm</a> as a nice quick example of matrix manipulations. I'd like to include the information of which graphics libraries actually implement this, and I wasn't able to find anything other than the linked 2007 webpage referencing "ImageMagick, pnmrotate, etc". Can anyone give an updated, larger list?</p>

CC BY-SA 4.0
2019-01-25T18:16:12.460Z
I guess this question might belong on math-educators, since I'm teaching in the math dept, but I figured CS educators would be more likely to know this. Feel free to migrate.
David E Speyer
CC BY-SA 4.0
2019-01-25T18:16:38.757Z
Also, is there a tag like `libraries` I should be using? Or would someone please create one? Thanks!
David E Speyer
CC BY-SA 4.0
2019-01-25T18:39:30.877Z
This isn't in my wheelhouse, but it is certainly topical here.
Ben I.
CC BY-SA 4.0
2019-01-25T19:01:09.997Z
Unfortunately a bit specialized for this audience. I wonder if StackOverflow might be a better place to find people with their heads deep in the libraries. But I also wonder why you want this. Do you intend for students to explore the code? That might be worth doing, though library code might be a bit messy with specialized bits and pieces obscuring the algorithm.
Buffy
CC BY-SA 4.0
2019-01-25T20:15:57.363Z
Is there any particular reason why you need a large list of libraries? Over here, we're generally helpful with questions about lesson plans, teaching techniques and things like that, but we generally aren't good with questions like this since we aren't necessarily knowledgeable about practical CS. If you could give some context about the lesson you're trying to use this list in, we could probably be much more helpful. However, if you just need this list, it'd probably be best for you to try another site, since we don't really  have the experts to answer this.
thesecretmaster
CC BY-SA 4.0
2019-01-26T13:28:11.480Z
As others have noted, this is a highly specialized question. Even though I have been using image libraries for decades in the practical sense, and have probably used the algorithm, I have never heard of the Paeth algorithm until now. Users of libraries typically don't look beyond "will it do what I need?" And "how do I make it work?"
pojo-guy
CC BY-SA 4.0
2019-01-28T08:00:40.377Z
One more thought: I would assume that most image processing libraries are rotating using other algorithms due to interpolation issues, but I'm not really an expert in this field so I might be wrong.
OBu
<image-processing>
Which image rotation libraries use the Paeth algorithm?
# Which image rotation libraries use the Paeth algorithm?

(Asked by: username_0 on 2019-01-25)

I'm teaching linear algebra, and thought I'd show my students [Paeth's rotation by shearing algorithm](https://www.ocf.berkeley.edu/~fricke/projects/israel/paeth/rotation_by_shearing.html) as a nice quick example of matrix manipulations. I'd like to include the information of which graphics libraries actually implement this, and I wasn't able to find anything other than the linked 2007 webpage referencing "ImageMagick, pnmrotate, etc". Can anyone give an updated, larger list?

**Tags:** image-processing

> **Comments:**
> **username_0**: I guess this question might belong on math-educators, since I'm teaching in the math dept, but I figured CS educators would be more likely to know this. Feel free to migrate.  
> **username_0**: Also, is there a tag like `libraries` I should be using? Or would someone please create one? Thanks!  
> **username_1**: This isn't in my wheelhouse, but it is certainly topical here.  
> **username_2**: Unfortunately a bit specialized for this audience. I wonder if StackOverflow might be a better place to find people with their heads deep in the libraries. But I also wonder why you want this. Do you intend for students to explore the code? That might be worth doing, though library code might be a bit messy with specialized bits and pieces obscuring the algorithm.  
> **username_3**: Is there any particular reason why you need a large list of libraries? Over here, we're generally helpful with questions about lesson plans, teaching techniques and things like that, but we generally aren't good with questions like this since we aren't necessarily knowledgeable about practical CS. If you could give some context about the lesson you're trying to use this list in, we could probably be much more helpful. However, if you just need this list, it'd probably be best for you to try another site, since we don't really  have the experts to answer this.  
> **username_4**: As others have noted, this is a highly specialized question. Even though I have been using image libraries for decades in the practical sense, and have probably used the algorithm, I have never heard of the Paeth algorithm until now. Users of libraries typically don't look beyond "will it do what I need?" And "how do I make it work?"  
> **username_5**: One more thought: I would assume that most image processing libraries are rotating using other algorithms due to interpolation issues, but I'm not really an expert in this field so I might be wrong.  

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## 0 answers

