Observation of a zoom-engine of PS

[Dmitry Kazakov-2]

Hi!

Just an observation i got today while using PS7.  =)
It has quite good and fast zooming engine. And the most interesting fact about that - it uses different zoom-algorithms for different zoom-levels.
More exactly:

For zoom-levels 100,50,25,12.5 - it uses smooth-scale algorithm
For other levels - nearest-neighbor. More than that, it uses nearest prescaled(?) image for NN-sampling.

--
Dmitry Kazakov

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On Sunday 01 November 2009, Dmitry Kazakov wrote:
> Hi!
>
> Just an observation i got today while using PS7.  =)
> It has quite good and fast zooming engine. And the most interesting fact
> about that - it uses different zoom-algorithms for different zoom-levels.

Well, so do we -- or, since I haven't checked recently, maybe used to do. Our
scheme was smooth < 100%, nn > 100% or something like that.

> More exactly:
>
> For zoom-levels 100,50,25,12.5 - it uses smooth-scale algorithm
> For other levels - nearest-neighbor. More than that, it uses nearest
> prescaled(?) image for NN-sampling.
>


--
Boudewijn Rempt | http://www.valdyas.org
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On Sunday 01 November 2009 15:25:58 Dmitry Kazakov wrote:

> Hi!
>
> Just an observation i got today while using PS7.  =)
> It has quite good and fast zooming engine. And the most interesting fact
> about that - it uses different zoom-algorithms for different zoom-levels.
> More exactly:
>
> For zoom-levels 100,50,25,12.5 - it uses smooth-scale algorithm
> For other levels - nearest-neighbor. More than that, it uses nearest
> prescaled(?) image for NN-sampling.
>

In Krita's OpenGL canvas we use linear interpolation (you called that smooth-
scale) for zoom level below 200 % and nearest neighbour for the levels above.
Check kis_opengl_canvas2.cpp (line 223).

 
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[Dmitry Kazakov-2]

On Mon, Nov 2, 2009 at 12:21 AM, LukasT.dev@... <lukast.dev@...> wrote:

On Sunday 01 November 2009 15:25:58 Dmitry Kazakov wrote:
> Hi!
>
> Just an observation i got today while using PS7.  =)
> It has quite good and fast zooming engine. And the most interesting fact
> about that - it uses different zoom-algorithms for different zoom-levels.
> More exactly:
>
> For zoom-levels 100,50,25,12.5 - it uses smooth-scale algorithm
> For other levels - nearest-neighbor. More than that, it uses nearest
> prescaled(?) image for NN-sampling.
>

In Krita's OpenGL canvas we use linear interpolation (you called that smooth-
scale) for zoom level below 200 % and nearest neighbour for the levels above.
Check kis_opengl_canvas2.cpp (line 223).

QPainter canvas works right the same way =)

--
Dmitry Kazakov

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